EA040874B1 - BACKWARDS COMPATIBLE ARRANGEMENT OF A HARMONIC TRANSPOSER FOR RECONSTRUCTION OF HIGH FREQUENCY SOUND SIGNALS - Google Patents

Description

The technical field to which the invention belongs

The embodiments are related to audio signal processing, more specifically to encoding, decoding or transcoding audio bitstreams with control data specifying whether a basic form of high frequency reconstruction (HFR) or an advanced form of HFR is to be performed on the audio data.

State of the art invention

A typical audio bitstream includes both audio data (eg, encoded audio data) indicative of one or more audio content channels and metadata indicative of at least one characteristic of the audio data or audio content. One well-known format for generating an encoded audio bitstream is the MPEG-4 Advanced Audio Coding (AAC) format described in the ISO/IEC 14496-3:2009 MPEG standard. In the MPEG-4 standard, AAC stands for Advanced Audio Coding and HE-AAC stands for High Efficiency Advanced Audio Coding.

The AAC MPEG-4 standard defines several audio profiles that define what objects and encoders are present in a compatible encoder or decoder. Three of these audio profiles are (1) the AAC profile, (2) the HE-AAC profile, and (3) the HE-AAC v2 profile. The AAC Profile includes the AAC (or AAC-LC) Low Complexity Object Type. The AAC-LC entity is analogous to the MPEG-2 AAC Low Complexity Profile with some adjustments, and includes neither the Spectrum Band Replication (SBR) entity type nor the Parametric Stereo (PS) entity type. The HE-AAC profile is a superset of the AAC profile and additionally includes the SBR object type. The HE-AAC v2 profile is a superset of the HE-AAC profile and additionally includes the PS object type.

The SBR object type contains a band replication engine, which is an important high frequency reconstruction (HFR) coding engine that greatly improves the compression efficiency of perceptual audio codecs. SBR reconstructs the high frequency components of the audio signal at the receiver side (eg, in a decoder). Thus, the encoder only needs to encode and transmit the low frequency components, allowing for much higher audio quality at low bit rates. SBR is based on the replication of harmonic sequences, previously truncated in order to reduce the data rate, from the available bandwidth limited signal and the control data received from the encoder. The relationship between tonal and noise-like components is maintained through adaptive inverse filtering, as well as the optional addition of noise and sinusoidal signals. In the MPEG-4 AAC standard, the SBR facility performs a spectral patch (also called a linear transform or spectral transform) in which a number of successive quadrature mirror filter (QMF) subbands are copied (or pasted) from the transmitted portion of the low frequency band. of the audio signal into a part of the high frequency band of the audio signal, which is formed in the decoder.

Spectral patching or linear transformation may not be ideal for some types of audio signal, such as music content with relatively low crossover frequencies. Therefore, technologies are needed to improve the replication of spectrum bands.

Brief description of embodiments of the invention

A first group of embodiments is disclosed that relates to a method for decoding an encoded audio bitstream. The method includes receiving an encoded audio bit stream and decoding the audio data to generate a decoded audio signal in a low band. The method further includes extracting high frequency reconstruction metadata and filtering the decoded low band audio signal with a signal decomposition filter bank to generate a filtered low band audio signal. The method further includes extracting a flag flag indicating whether spectral transformation or harmonic transposition should be performed on the audio data, and restoring a high frequency portion of the audio signal using a filtered audio signal in the low band and high frequency reconstruction metadata in accordance with the flag flag. Finally, the method includes combining the filtered low band audio signal and the reconstructed high band portion to form a wideband audio signal.

The second group of embodiments relates to an audio decoder for decoding an encoded audio bitstream. The decoder includes an input interface for receiving an encoded audio bitstream, where the encoded audio bitstream includes audio data constituting a low frequency part of an audio signal, and a main decoder for decoding audio data to generate a decoded audio signal in a low band. The decoder also includes a demultiplexer for extracting high frequency reconstruction metadata from the encoded audio bitstream, where the high frequency reconstruction metadata includes operating parameters for a high frequency reconstruction process that linearly transforms a number of consecutive subbands from a portion a low band of the audio signal to a high band part of the audio signal, and a signal decomposition filter bank for filtering the decoded audio signal in the low band to generate a filtered audio signal in the low band. The decoder further includes a demultiplexer for extracting from the encoded audio bitstream a flag indicating whether a linear transformation or a harmonic transposition should be performed on the audio data, and a high frequency restorer for restoring the high frequency part of the audio signal using the filtered audio signal in the low band. and high frequency reconstruction metadata according to the flag. Finally, the decoder includes a signal synthesis filter bank for combining the filtered low band audio signal and the reconstructed high band portion to generate a wideband audio signal.

Other groups of embodiments relate to the encoding and transcoding of audio bitstreams containing metadata identifying whether enhanced spectrum band replication (eSBR) processing is to be performed.

Brief description of the drawings

Fig. 1 is a block diagram of an embodiment of a system that may be configured to perform an embodiment of an inventive method.

Fig. 2 is a block diagram of an encoder which is an embodiment of an inventive audio processing unit.

Fig. 3 is a block diagram of a system including a decoder, which is an embodiment of an inventive audio processing unit, and optionally also a post-processor coupled thereto.

Fig. 4 is a block diagram of a decoder which is an embodiment of an inventive audio processing unit.

Fig. 5 is a block diagram of a decoder which is another embodiment of an inventive audio processing unit.

Fig. 6 is a block diagram of yet another embodiment of an inventive audio processing unit.

Fig. 7 is a block diagram of an AAC MPEG-4 bitstream including segments into which it is divided.

Notation and terminology

Throughout this specification, including in the claims, the expression performing an operation on a signal or data (e.g., filtering, scaling, transforming, or applying a gain to a signal or data) is used broadly to mean performing an operation directly on a signal or data, or on a processed version of a signal or data (for example, on a signal version that has undergone pre-filtering or pre-processing before performing an operation on it).

Throughout this specification, including in the claims, the expression audio processing unit or audio processor is used in a broad sense to refer to a system, device, or installation capable of processing audio data. Examples of audio signal processing units include, but are not limited to, encoders, transcoders, decoders, codecs, pre-processing systems, post-processing systems, and bitstream processing systems (sometimes referred to as bitstream processors). Almost all consumer electronics, such as mobile phones, televisions, laptops, tablet computers, contain an audio signal processing unit or sound processor.

Throughout this description of the invention, including in the claims, the term attached or attached is used in a broad sense to mean a direct or indirect connection. Thus, if a first device is connected to a second device, the connection may be through a direct connection or through an indirect connection using other devices and connections. Moreover, components that are combined in or with other components are also connected to each other.

Detailed description of embodiments of the invention

The MPEG-4 AAC standard assumes that an MPEG-4 AAC encoded bitstream includes metadata indicating each type of High Frequency Reconstruction (HFR) processing to be performed (if any) by a decoder to decode the audio content of the bitstream, and/or which control such HFR processing and/or indicate at least one characteristic or parameter of at least one HFR means to be used for decoding the audio content of the bitstream. Throughout the present invention, we use the expression SBR metadata to refer to this type of metadata, which is described or referred to in the AAC MPEG-4 standard for use with spectrum band replication.

- 2 040874 (SBR). As will be appreciated by those skilled in the art, SBR is a subset of HFR.

SBR is preferably used as a dual sample rate system, wherein the underlying codec operates at half the original sample rate while SBR operates at the original sample rate. The SBR encoder runs in parallel with the underlying main codec, albeit at a higher sampling rate. Although SBR is primarily post-processed in the decoder, important parameters are extracted in the encoder in order to provide the most accurate high frequency reconstruction in the decoder. The encoder estimates the spectral envelope of the SBR band as to the time-frequency range/time and frequency resolution appropriate for the characteristics of the current segments of the input signal. The envelope of the spectrum is estimated by decomposing the signal with complex FFTs and then calculating the energy. The time and frequency resolutions of the spectrum envelopes can be selected with a high degree of freedom in order to provide the best time and frequency resolution for a given segment of the input signal. Envelope estimation should take into account that a transient in the original, mainly located in the high frequency region (e.g., high overshoot), will be present to a small extent in the SBR generated high band before envelope correction, since the high band in the decoder is based on the low band. frequencies, where the transient process is expressed to a much lesser extent compared to the high frequency band. This aspect imposes different requirements on the time and frequency resolution of the spectrum envelope data compared to conventional spectrum envelope estimation as used in other audio coding algorithms.

In addition to the spectrum envelope, several additional parameters are extracted, which are the spectral characteristics of the input signal for different frequency-time domains. Since the encoder naturally has access to the original signal, as well as information on how the SBR block in the decoder will create the high frequency band, given a certain set of control parameters, it is possible for the system to cope with situations where the low frequency band is a powerful harmonic series, and the high frequency band to be recreated mainly constitutes random signal components, as well as situations where strong tonal components are present in the original high frequency band with no analogues in the low frequency band on which the high frequency region is based. Moreover, the SBR encoder works closely with the underlying underlying codec to estimate which frequency range should be covered by the SBR at a given time. The SBR data is rationally encoded before transmission by using entropy coding as well as control data channel dependencies, in the case of stereo signals.

Control parameter extraction algorithms typically need to be carefully tuned to the underlying codec at a given bit rate and a given sample rate. This is due to the fact that a lower bit rate typically relies on a larger SBR range compared to a high bit rate, and different sample rates correspond to different time resolutions of the SBR frames.

An SBR decoder typically includes several different parts. It contains a bitstream decoding module, a high frequency restoration (HFR) module, an additional high frequency components module, and an envelope corrector module. The system is based on a filter bank of complex-valued KZFs. In the bitstream extractor, control data is read from the bitstream and decoded. The time/frequency grid is obtained for the current frame before the envelope data is read from the bitstream. The underlying main decoder decodes the audio signal of the current frame (albeit at a lower sampling rate) to create audio samples in the time domain. The resulting audio data frame is used to reconstruct the high frequencies by the HFR module. The decoded lowband signal is then subjected to signal decomposition using a filterbank of the CPF. High frequency reconstruction and envelope correction are subsequently performed on the filterbank sub-band samples from the FAP. The high frequencies are reconstructed from the low frequency band in a flexible manner based on the given control parameters. Moreover, the reconstructed high band is adaptively filtered based on the subband channels according to the control data to provide proper spectral response in a given frequency/time domain.

The upper level of an MPEG-4 AAC bitstream is a sequence of data blocks (raw data block elements), each of which is a data segment (referred to herein as a block) that contains audio data (typically for a time period of 1024 or 960 samples) and related information and/or other data. Throughout the present invention, we use the term block to refer to a segment of an MPEG-4 AAC bitstream containing audio data (and associated metadata, and optionally also other associated data) that specifies or is indicative of one (but not more than one) raw_data_block element.

Each block of an AAC MPEG-4 bitstream may include a number of syntax elements (each of which is also materialized in the bitstream as a data segment). Seven types of such syntax elements are defined in the AAC MPEG-4 standard. Each syntax element is identified by a different value of the id_syn_ele data element. Examples of syntax elements include single_channel_element(), channel_pair_element(), and fill_element(). A single channel element is a container including audio data of a single audio channel (mono audio signal). The channel pair element includes audio data of two audio channels (ie, a stereo audio signal).

The padding element is a container of information including an identifier (eg, the value of the element id syn ele noted above) followed by data, which is referred to as padding data. Padding elements have historically been used to correct the instantaneous bit rate of bit streams to be transmitted over a constant bit rate channel. By adding an appropriate amount of padding data to each block, a constant data rate can be achieved.

In accordance with embodiments of the invention, the padding data may include one or more extension payloads that extend the type of data (eg, metadata) capable of being transmitted in the bitstream. The decoder that receives the bitstreams will be padding data containing the new data type, optionally used by the device receiving the bitstream (eg, decoder) to extend the functionality of the device. Thus, as can be appreciated by one of ordinary skill in the art, padding elements are a special type of data structure and are distinct from data structures typically used to convey audio data (eg, audio payloads containing channel data).

In some embodiments of the invention, the identifier used to identify the padding element may consist of a three-bit unsigned integer, transmitted most significant bit first (uimsbf), having a value of 0x6. Multiple instances of the same type of syntax element can appear in the same block (for example, multiple padding elements).

Another standard for encoding audio bitstreams is the MPEG Unified Voice and Audio Coding (USAC) standard (ISO/IEC 23003-3:2012). The USAC MPEG standard describes the encoding and decoding of audio content using band replication processing (including SBR processing as described in the AAC MPEG-4 standard, and further including other advanced forms of band replication processing). This processing uses spectrum band replication tools (sometimes referred to in the materials of the present invention as advanced SBR tools or eSBR tools) of an extended and improved version of the SBR tool set described in the AAC MPEG-4 standard. Thus, eSBR (as defined in the USAC standard) is an improvement over SBR (as defined in the AAC MPEG-4 standard).

Throughout the present invention, we use the term advanced SBR processing (or eSBR processing) to refer to spectrum band replication processing using at least one eSBR facility (e.g., at least one eSBR facility as described or referred to in the USAC MPEG standard) that not described or mentioned in the AAC MPEG-4 standard. Examples of such eSBR tools are harmonic transposition and post-pasting post-processing with CZF or pre-alignment.

An integer-order harmonic transposer T maps a sinusoid of frequency co to a sinusoid of frequency Tco, while preserving the signal's duration. Three orders, T=2, 3, 4, are typically used sequentially to create each portion of the desired output frequency range using the smallest transposition order possible. If an output signal above the fourth order transposition range is required, it can be generated by frequency shifts. When possible, nearly critically sampled baseband time domains are created for processing to minimize computational complexity.

A bitstream generated in accordance with the USAC MPEG standard (sometimes referred to as a USAC bitstream in the present invention) includes encoded audio content and typically includes metadata indicating each type of spectrum replication processing to be applied by a decoder for decoding audio content of the USAC bitstream, and/or metadata that controls such replication processing of the spectrum bands or indicates at least one characteristic or parameter of at least one SBR and/or eSBR that should be used to decode the audio content of the USAC bitstream.

Throughout the present invention, we use the expression advanced SBR metadata (or eSBR metadata) to refer to metadata indicating each type of spectrum replication processing that should be applied by a decoder to decode the audio content of an encoded audio bitstream (e.g., a USAC bitstream), and/or which control such spectral band replication processing and/or indicate at least one characteristic or

- 4 040874 parameter of at least one SBR and/or eSBR to be used to decode such audio content, but which is not described or mentioned in the AAC MPEG-4 standard. An example of eSBR metadata is metadata (indicating or intended to control the processing of spectrum band replication) that is described or referred to in the USAC MPEG standard, but not in the AAC MPEG-4 standard. Thus, eSBR metadata in the materials of the present invention refers to metadata that is not SBR metadata, and SBR metadata in the materials of the present invention refers to metadata that is not eSBR metadata.

The USAC bitstream may include both SBR metadata and eSBR metadata. More specifically, the USAC bitstream may include eSBR metadata that controls the execution of eSBR processing by the decoder and SBR metadata that controls the execution of SBR processing by the decoder. In accordance with exemplary embodiments of the present invention, Esbr metadata (eg, eSBR specific configuration data) according to the present invention included in an MPEG-4 AAC bitstream (eg, in the sbr_extension() container at the end of the SBR payload).

Performing eSBR processing during decoding of the encoded bitstream using the eSBR facility (comprising at least one eSBR facility) set by the decoder recovers the audio highband based on the replication of the harmonic sequences that were truncated during encoding. Such eSBR processing typically corrects the spectral envelope of the shaped high frequency band and applies inverse filtering, noise and sine components in order to recreate the spectral characteristics of the original audio signal.

In accordance with exemplary embodiments of the invention, eSBR metadata is included (e.g., a small number of control bits that are eSBR metadata are included) in one or more metadata segments of an encoded audio bitstream (e.g., an MPEG-4 AAC bitstream), which also includes encoded audio data in other segments (audio data segments). Typically, at least one such metadata segment of each bitstream block is (or includes) a padding element (including an identifier indicating the start of the padding element), and the eSBR metadata is included in the padding element after the identifier. Fig. 1 is a block diagram of an exemplary audio signal processing circuit (audio data processing system) in which one or more of the system elements may be implemented in accordance with an embodiment of the present invention. The system includes the following elements connected to each other as shown: an encoder 1, a delivery subsystem 2, a decoder 3 and a post-processing unit 4. In variations of the system shown, one or more elements are not included, or additional audio data processing units are included.

In some implementations, encoder 1 (which optionally includes a pre-processor) is configured to receive PCM (time domain) samples containing audio content as input and output an encoded audio bitstream (having a format that is compatible with the AAC standard). MPEG-4) which is indicative of audio content. Bitstream data that indicates audio content is sometimes referred to as audio data or encoded audio data in the materials of the present invention. If the encoder is implemented in accordance with an exemplary embodiment of the present invention, the audio bitstream output from the encoder includes eSBR metadata (and typically other metadata as well) as well as audio data.

One or more encoded audio streams output from encoder 1 may be presented to encoded audio delivery subsystem 2. Subsystem 2 is configured to store and/or deliver each encoded bitstream output from encoder 1. The encoded audio bitstream output from encoder 1 may be stored by subsystem 2 (for example, as a DVD or Bluray disc) or transmitted by subsystem 2 (which may implement a transmission channel or network), or may be both stored and transmitted by subsystem 2.

Decoder 3 is configured to decode an encoded AAC MPEG-4 audio bitstream (generated by encoder 1) that it receives via subsystem 2. In some embodiments, decoder 3 is configured to extract eSBR metadata from each block of the bitstream and decode the bitstream ( including by performing eSBR processing using the extracted eSBR metadata) to generate decoded audio data (eg, PCM decoded audio sample streams). In some embodiments, the decoder 3 is configured to extract the SBR metadata from the bitstream (but ignore the eSBR metadata included in the bitstream) and decode the bitstream (including by performing SBR processing using the extracted SBR metadata) to generate decoded audio data. (e.g., streams of decoded PCM audio samples. Typically, decoder 3 includes a buffer that stores (e.g., in a non-ephemeral manner) segments of the encoded audio bitstream received from subsystem 2.

- 5 040874

The post-processing block 4 of FIG. 1 is configured to receive the decoded audio data stream from the decoder 3 (eg, PCM audio samples) and perform post-processing on it. The post-processing unit may also be configured to play the post-processed audio content (or the decoded audio signal received from the decoder 3) for playback by one or more speakers.

Fig. 2 is a block diagram of an encoder (100), which is an embodiment of an inventive audio processing unit. Any of the components or elements of encoder 100 may be implemented as one or more processes and/or one or more circuits (e.g., ASICs, FPGAs, or other integrated circuits) in hardware, software, software or a combination of hardware and software. The encoder 100 includes an encoder 105, a filler/formatter stage 107, a metadata generation stage 106, and a buffer memory 109 connected as shown. Also, encoder 100 typically includes other processing elements (not shown). The encoder 100 is configured to convert the input audio bitstream into an AAC MPEG-4 encoded output bitstream.

Metadata generator 106 is coupled and configured to generate (and/or pass through to cascade 107) metadata (including eSBR metadata and SBR metadata) to be included by cascade 107 in the encoded bitstream to be output from encoder 100.

An encoder 105 is coupled to and configured to encode (eg, compress) the input audio data and provide the resulting encoded audio signal to stage 107 for inclusion in an encoded bitstream to be output from stage 107.

Stage 107 is configured to multiplex the encoded audio signal from encoder 105 and metadata (including eSBR metadata and SBR metadata) from generator 106 to generate an encoded bitstream to be output from stage 107, preferably such that the encoded bitstream has the format , as given by one of the embodiments of the present invention.

Buffer memory 109 is configured to store (eg, in a non-ephemeral manner) at least one block of the encoded audio bitstream output from stage 107, and the sequence of blocks of encoded audio bitstream is then presented from buffer memory 109 as output from encoder 100 to the system. delivery.

Fig. 3 is a block diagram of a system including a decoder (200), which is an embodiment of an inventive audio processing unit, and optionally also a post-processor (300) coupled thereto. Any of the components or elements of decoder 200 and post processor 300 may be implemented as one or more processes and/or one or more circuits (e.g., ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), or other integrated circuits) in hardware means, software, or a combination of hardware and software. The decoder 200 includes a buffer memory 201, a bitstream payload deformer (parser) 205, an audio signal decoding subsystem 202 (sometimes referred to as a main decoding stage or a main decoding subsystem), an eSBR processing stage 203, and a control bit generating stage 204 connected as shown. . Also, typically, decoder 200 includes other processing elements (not shown).

Buffer memory 201 (buffer) stores (e.g., in a non-ephemeral manner) at least one block of the MPEG-4 AAC encoded audio bitstream received by decoder 200. In operation of decoder 200, a sequence of bitstream blocks is presented from buffer 201 to deformer 205.

In a variation of the embodiment in FIG. 3, an APU that is not a decoder (eg, APU 500 of FIG. 6) includes a buffer memory (eg, buffer memory identical to buffer 201) that stores (eg, in a non-ephemeral manner) at least one encoded audio bit block. a stream (eg, an AAC MPEG-4 audio bitstream) of the same type received by the buffer 201 of FIG. 3 or fig. 4 (ie, an encoded audio bitstream that includes eSBR metadata).

Again with reference to FIG. 3, a deformer 205 is coupled and configured to demultiplex each bitstream block to extract SBR metadata (including quantized envelope data) and eSBR metadata (and typically other metadata as well) from it, present at least the eSBR metadata and SBR metadata in eSBR processing stage 203 and typically also present other extracted metadata to decoding subsystem 202 (and optionally also to control bit generator 204). A deformer 205 is also attached and configured to extract audio data from each bitstream block and present the extracted audio data to a decoding subsystem 202 (decoding stage).

The system according to Fig. 3 optionally also includes a post processor 300. The post processor 300 includes a buffer memory 301 (buffer) and other processing elements (not shown), including at least one processing element attached to the buffer 301. Buffer 301 stores (eg, in a non-ephemeral manner) at least one block (or frame) of decoded audio data received by post processor 300 from decoder 200. Processing elements of post processor 300 are coupled and configured to receive and adaptively process a sequence of blocks (or frames) of decoded audio signal outputted from buffer 301 using metadata outputted from decoding subsystem 202 (and/or deformer 205) and/or control bits outputted from stage 204 of decoder 200.

The audio decoding subsystem 202 of the decoder 200 is configured to decode the audio data extracted by the parser 205 (such decoding may be referred to as a main decoding operation) to generate decoded audio data and provide the decoded audio data to the eSBR processing stage 203. The decoding is performed in the frequency domain and typically includes dequantization followed by spectral processing. Typically, the final processing stage in subsystem 202 applies a frequency domain to time domain transform to the decoded frequency domain audio data such that the output of the subsystem is the decoded time domain audio data. Cascade 203 is configured to apply SBR and eSBR means indicated by SBR metadata and eSBR metadata (extracted by parser 205) to decoded audio data (i.e., perform SBR and eSBR processing on the output of decoding subsystem 202 using SBR and eSBR metadata) to generate fully decoded audio data that is output (e.g., to post processor 300) from decoder 200. Typically, decoder 200 includes memory (accessible from subsystem 202 and stage 203) that stores deformed audio data and metadata output from deformer 205, and stage 203 is configured to access audio data and metadata (including SBR metadata and eSBR metadata) as needed during SBR and eSBR processing. The SBR processing and eSBR processing in the cascade 203 may be considered post-processing at the output of the main decoding subsystem 202 . Optionally, decoder 200 also includes a post-upmix subsystem (which may apply the parametric stereo (PS) facilities defined in the MPEG-4 AAC standard using PS metadata extracted by deformer 205 and/or control bits generated in subsystem 204 ) that is coupled to and configured to up-mix the output of stage 203 to generate a fully decoded up-mixed audio signal that is output from decoder 200. Alternatively, post-processor 300 is configured to up-mix the output of decoder 200 ( eg, using PS metadata extracted by deformer 205 and/or control bits generated in subsystem 204).

In response to the metadata extracted by the deformer 205, the control bit generator 204 may generate control data, and the control data may be used within the decoder 200 (e.g., in a post-upmix subsystem) and/or presented as an output signal of the decoder 200 (e.g., in post processor 300 for use in post-processing). In response to metadata extracted from the input bitstream (and optionally also in response to control data), stage 204 may generate (and present to post processor 300) control bits indicating that the decoded audio data output from processing stage 203 eSBR must be subject to a particular type of post-processing. In some embodiments, decoder 200 is configured to provide metadata extracted by deformer 205 from the input bitstream to post processor 300, and post processor 300 is configured to perform post processing on the decoded audio data output from decoder 200 using the metadata.

Fig. 4 is a block diagram of an audio processing unit (APU) (210), which is another embodiment of an inventive audio processing unit. APU 210 is a legacy decoder that is not configured to perform eSBR processing. Any of the components or elements of the APU 210 may be implemented as one or more processes and/or one or more circuits (e.g., ASICs, FPGAs, or other integrated circuits) in hardware, software, software or a combination of hardware and software. The APU 210 includes a buffer memory 201, a bitstream payload deformer (parser) 215, an audio signal decoding subsystem 202 (sometimes referred to as a main decoding stage or a main decoding subsystem), and an SBR processing stage 213 connected as shown. Also, typically APU 210 includes other processing elements (not shown). APU 210, for example, may be an audio encoder, decoder, or transcoder.

Elements 201 and 202 of APU 210 are identical to the identically numbered elements of decoder 200 (according to

- 7 040874 fig. 3), and the above description of them will not be repeated. In operation of the APU 210, a block sequence of the encoded audio bitstream (MPEG-4 AAC bitstream) received by the APU 210 is presented from the buffer 201 to the deformer 215.

A deformer 215 is attached and configured to demultiplex each bitstream block to extract SBR metadata (including quantized envelope data) and also typically other metadata from it, but ignore eSBR metadata that may be included in the bitstream, according to any embodiment of the present invention. The deformer 215 is configured to add at least SBR metadata to the SBR processing stage 213 . A deformer 215 is also attached and configured to extract audio data from each block of the bitstream, and present the extracted audio data to a decoding subsystem 202 (decoding stage).

The audio decoding subsystem 202 of the decoder 200 is configured to decode the audio data extracted by the deformer 215 (such decoding may be referred to as a main decoding operation) to generate decoded audio data and provide the decoded audio data to the SBR processing stage 213 . The decoding is performed in the frequency domain. Typically, the final processing stage in subsystem 202 applies a frequency domain to time domain transform to the decoded frequency domain audio data such that the output of the subsystem is the decoded time domain audio data. Stage 213 is configured to apply the SBR means (but not the eSBR means) indicated by the SBR metadata (extracted by the deformer 215) to the decoded audio data (i.e., perform SBR processing on the output of the decoding subsystem 202 using the SBR metadata) to generate fully decoded audio data that is output (eg, to post processor 300) from APU 210. Typically, APU 210 includes a memory (accessible from subsystem 202 and stage 213) that stores deformed audio data and metadata output from deformer 215, and stage 213 is configured with the ability to access audio data and metadata (including SBR metadata) as needed during SBR processing. The SBR processing at stage 213 may be considered post-processing at the output of main decoding subsystem 202. Optionally, the APU 210 also includes a post-upmix subsystem (which can apply the Parametric Stereo (PS) facilities defined in the AAC MPEG-4 standard using the PS metadata extracted by the deformer 215) that is coupled and configured to perform the upmix. over the output of stage 213 to generate a fully decoded upmixed audio signal that is output from APU 210. Alternatively, a post processor is configured to upmix the output of APU 210 (for example, using PS metadata extracted by deformer 215, and /or control bits generated in the APU 210).

Various implementations of encoder 100, decoder 200, and APU 210 are configured to perform various embodiments of the inventive method.

In accordance with some embodiments, eSBR metadata is included (e.g., a small number of control bits that are eSBR metadata are included) in an encoded audio bitstream (e.g., an MPEG-4 AAC bitstream) so that legacy decoders (which are not configured to parse the eSBR metadata and use whatever eSBR facility the eSBR metadata refers to) may ignore the eSBR metadata but still decode the bitstream as far as possible without using the eSBR metadata or any eSBR facility , to which the eSBR metadata refers, typically without any significant degradation in the quality of the decoded audio signal. However, eSBR decoders configured to parse the bitstream to identify eSBR metadata and to use at least one eSBR engine in response to the eSBR metadata will benefit from using at least one such eSBR engine. Therefore, embodiments of the invention provide a means for intelligently transmitting enhanced spectrum band replication (eSBR) control data or metadata in a backwards compatible manner.

Typically, eSBR metadata in a bitstream is indicative of (e.g., indicative of at least one characteristic or parameter) one or more of the following eSBR facilities (which are described in the MPEG USAC standard and which may or may not have been applied by the encoder at the time the bitstream was generated): :

harmonic transposition; and additional pre-treatment by bonding with KZF (pre-levelling).

For example, eSBR metadata included in the bitstream may be indicative of parameter values (described in the USAC MPEG standard and in the present invention): sbrPatchingMode[ch], sbrOversamplingFlag[ch], sbrPitchInBins[ch], sbrPitchInBins[ch], and bs_sbr_preprocessing.

- 8 040874

In the materials of the present invention, the notation X[ch], where X is some parameter, denotes that the parameter refers to the channel (ch) of the audio content of the encoded bitstream to be decoded. For the sake of simplicity, we sometimes omit the [ch] expression and assume that the corresponding parameter refers to an audio content channel.

In the materials of the present invention, the notation X[ch][env], where X is a parameter, indicates that the parameter refers to the envelope (env) of the SBR channel (ch) of the audio content of the encoded bitstream to be decoded. For the sake of simplicity, we sometimes omit the expressions [env] and [ch] and assume that the corresponding parameter refers to the SBR envelope of the audio content channel.

During decoding of an encoded bitstream, the performance of harmonic transposition during the eSBR processing stage of decoding (for each channel, ch, of the audio content indicated by the bitstream) is controlled by the following eSBR metadata parameters: sbrPatchingMode[ch]: sbrOversamplingFlag[ch]; sbrPitchInBinsFlag[ch]; and sbrPitchInBins[ch].

The value of sbrPatchingMode[ch] indicates the type of transposer used in eSBR: sbrPatchingMode[ch]=1 indicates non-harmonic patching as described in section 4.6.18.6.3 of the AAC MPEG-4 standard; sbrPatchingMode[ch]=0 specifies SBR harmonic patching as specified in section 7.5.3 or 7.5.4 of the USAC MPEG USAC standard.

The value of sbrOversamplingFlag[ch] specifies the use of signal-adaptive frequency domain oversampling in the eSBR in combination with DFT-based SBR harmonic patching as described in section 7.5.3 of the USAC MPEG standard. This flag controls the size of the DFTs that are used in the transposer: 1 indicates signal-adaptive frequency domain resampling is enabled, as described in section 7.5.3.1 of the USAC MPEG standard; 0 indicates signal-adaptive frequency domain resampling disabled, as described in section 7.5.3.1 of the USAC MPEG standard.

The value of sbrPitchInBinsFlag[ch] controls the interpretation of the sbrPitchInBins[ch] parameter: 1 indicates that the value in sbrPitchInBins[ch] is valid and greater than zero; 0 indicates that sbrPitchInBins[ch] is set to zero.

The sbrPitchInBins[ch] value controls the addition of vector product terms to the SBR harmonic transposer. The value of sbrPitchinBins[ch] is an integer value in the range [0,127] and is the distance measured in frequency bins for a 1536-point DFT operating at the core encoder sample rate.

In case the MPEG-4 AAC bitstream indicates a pair of SBR channels whose channels are not connected (instead of a single SBR channel), the bitstream is indicating two instances of the above syntax (for harmonic or non-harmonic transposition), one for each sbr_channel_pair_element() channel.

The harmonic transposition of the eSBR facility typically improves the quality of decoded music signals with relatively low crossover frequencies. Non-harmonic transposition (ie, inherited spectral patching) typically enhances speech signals. Hence, the starting point in deciding which type of transposition is preferred for encoding a particular audio content is to choose a transposition method depending on speech/music detection, whereby harmonic transposition is performed over musical content and spectral pasting over speech content. content.

The performance of pre-alignment during eSBR processing is controlled by the value of a one-bit eSBR metadata parameter known as bs_sbr_preprocessing, in the sense that pre-alignment is performed or not performed depending on the value of this single bit. When using the SBR embedding algorithm as described in section 4.6.18.6.3 of the MPEG-4 AAC standard, a pre-equalization step may be performed (when specified by the bs_sbr_preprocessing parameter) in an attempt to avoid a discontinuity in the spectral envelope profile of the high frequency signal fed to the subsequent equalizer envelope (envelope corrector acts as another stage of eSBR processing). The pre-equalization typically improves the performance of the subsequent envelope correction stage, resulting in a high-band signal that is perceived to be more robust.

It is expected that the total bit rate requirement for inclusion in the MPEG-4 AAC bitstream eSBR metadata indicating the eSBR facilities mentioned above (harmonic transposition and pre-equalization) will be on the order of several hundred bits per second, since only the distinctive control data needed to perform eSBR processing are transmitted in accordance with some embodiments of the invention. Legacy decoders may ignore this information as it is included in a backward compatible manner (as will be explained later). Therefore, the detrimental bitrate impact associated with inclusion in eSBR metadata is negligible for a number of reasons, including the following:

the bit rate degradation (due to the inclusion of eSBR metadata) is a very small fraction of the total bit rate, as only the distinctive control data necessary to perform eSBR processing is transmitted (rather than the simultaneous transmission of SBR control data); and the setting of SBR-related control information is typically independent of the details of the transposition.

Thus, embodiments of the invention provide a means for intelligently transmitting enhanced spectrum band replication (eSBR) control data or metadata in a backwards compatible manner. The rational transmission of eSBR control data reduces the memory requirements in decoders, encoders, and transcoders employing aspects of the invention, while not incurring a perceptible adverse effect on the bit rate. Moreover, the complexity and processing requirements associated with performing eSBR in accordance with embodiments of the invention are also reduced because SBR data only needs to be processed once, and there is no simultaneous transmission that would occur if the eSBR were processed in full. a separate object type in AAC MPEG-4 instead of being embedded in the AAC MPEG-4 codec in a backward compatible manner.

Then, with reference to FIG. 7, we will describe the elements of a block (raw data block) of an MPEG-4 AAC bitstream in which eSBR metadata is included in accordance with some embodiments of the present invention. Fig. 7 is a block diagram (raw_data_block) of an MPEG-4 AAC bitstream showing some of its segments.

An MPEG-4 AAC bitstream block may include at least one single_channel_element() (e.g., the single channel element shown in FIG. 7) and/or at least one ”channel_pair_element() (not specifically shown in FIG. 7, although it may be present), including audio data for an audio program. The block may also include a number of fill_elements (eg, fill element 1 and/or fill element 2 of FIG. 7) including data (eg, metadata) related to the program. Each single_channel_element() includes an identifier (eg, ID1 of FIG. 7) indicating the start of a single channel element, and may include audio data indicating a different channel of the multi-channel audio program. Each channel_pair_element includes an identifier (not shown in FIG. 7) indicating the start of a channel pair element, and may include audio data indicating two program channels.

The fill element (referred to herein as a fill element) of an MPEG-4 AAC bitstream includes an identifier (ID2 in FIG. 7) indicating the start of the fill element and fill data after the identifier. The ID2 may consist of a 3-bit unsigned integer, transmitted most significant bit first (uimsbf), having the value 0xb. The payload data may include an extension_payload() element (sometimes referred to as an extension payload in the present invention), whose syntax is shown in Table 4.57 of the AAC MPEG-4 standard. Several extension payload types exist and are identified by the extension type parameter, which is a four-bit unsigned integer passed most significant bit first ('uimsbf').

The padding data (e.g., its extension payload) may include a header or identifier (e.g., header 1 of FIG. 7) that specifies a segment of the padding data that is indicative of an SBR object (i.e., the header initializes the SBR object type indicated by the reference like sbr_extension_data() in the AAC MPEG-4 standard). For example, a spectrum bands replication (SBR) extension payload is identified by a value of '1101' or '1110', with respect to the extension_type field in the header, where '1101' identifies an extension payload with SBR data, and '1110' identifies an extension payload with SBR data. with SBR data with a cyclic redundancy code (CRC) to check the correctness of the SBR data.

When a header (eg, an extension_type field) initializes an SBR object type, SBR metadata (sometimes referred to as spectrum band replication data and referred to as sbr_data() in the MPEG-4 AAC standard) follows the header, and at least one band replication extension element spectrum (eg, padding element 1 SBR extension element of FIG. 7) may follow the SBR metadata. Such a spectrum band replication extension element (bitstream segment) is referred to as the ”sbr_extension() container in the AAC MPEG-4 standard. The spectrum band replication extension element optionally includes a header (eg, padding element 1 SBR extension header of FIG. 7).

The MPEG-4 AAC standard suggests that the spectrum band replication extension element may include PS (parametric stereo) data for program audio data. The MPEG-4 AAC standard assumes that when the padding element header (eg, its extension payload) initializes the SBR object type (as header1 does in FIG. 7), and the padding element spectrum replication extension element includes PS data, the padding element (eg, its extension payload) includes spectrum band replication data, and a parameter bs_extension_id whose value (ie, bs_extension_id=2) indicates that the PS data is included in the padding element spectrum band replication extension element.

- 10 040874

In accordance with some embodiments of the present invention, eSBR metadata (eg, a flag indicating whether enhanced spectrum band replication (eSBR) processing should be performed on the audio content of the block). For example, such a flag is indicated in the padding element 1 of FIG. 7, where the flag feature occurs after the header (header of padding item 1 extension SBR) of padding item 1 SBR extension header. Optionally, such a flag and the additional eSBR data are included in the Bandwidth Replication Extension Element after the Bandwidth Replication Extension Element Header (eg, in the SBR Extension Element of Padding Element 1 in FIG. 7, after the SBR Extension Header). In accordance with some embodiments of the present invention, a padding element that includes eSBR metadata also includes a bs_extension_id parameter whose value (for example, bs_extension_id=3) indicates that eSBR metadata is included in the padding element and that eSBR processing should be performed on the sound content of the relevant block.

In accordance with some embodiments of the invention, the eSBR metadata is included in a padding element (e.g., padding element 2 of FIG. 7) of an MPEG-4 AAC bitstream other than in the spectrum band replication extension element (SBR extension element) of the padding element. The reason is that padding elements containing extension_payload() with SBR data or SBR data with CRC do not contain any other extension payload of any other type of extension. Therefore, in embodiments where the eSBR metadata is stored by its own extension payload, a separate padding element is used to store the eSBR metadata. Such a padding element includes an identifier (eg, ID2 of FIG. 7) indicating the start of the padding element and padding data after the identifier. The payload data may include an extension_payload() element (sometimes referred to throughout the present invention as an extension payload), whose syntax is shown in Table 1. 4.57 of the AAC MPEG-4 standard. The padding data (eg, its extension payload) includes a header (eg, header2 of padding element 2 of FIG. 7) that is indicative of an eSBR object (i.e., the header initializes an enhanced spectrum band replication (eSBR) object type), and data padding (eg, its extension payload) includes eSBR metadata after the header. For example, the padding element 2 of FIG. 7 includes such a header (header2) and also includes, after the header, eSBR metadata (i.e., a flag in padding element 2 that indicates whether advanced spectrum band replication (eSBR) processing should be performed on the audio content of the block). Optionally, additional eSBR metadata is also included in the padding data of the padding element 2 of FIG. 7 after header 2. In the embodiments described in this paragraph, the header (eg, header 2 of FIG. 7) has an identification value that is not one of the traditional values given in Table 7. 4.57 of the MPEG-4 AAC standard, and instead is indicative of the eSBR extension payload (so that the extension_type field indicates that the padding data includes eSBR metadata).

In a first group of embodiments, the invention is an audio signal processing unit (e.g., a decoder) comprising a memory (e.g., buffer 201 of FIG. 3 or 4) configured to store at least one encoded audio bitstream block (e.g., at least at least one block of an AAC MPEG-4 bitstream);

a bitstream payload deformer (eg, element 205 of FIG. 3 or element 215 of FIG. 4) coupled to the memory and configured to demultiplex at least one portion of said bitstream block; and a decoding subsystem (e.g., elements 202 and 203 of FIG. 3 or elements 202 and 213 of FIG. 4) coupled to and configured to decode at least one portion of the audio content of said bitstream block, the block including an element padding, including an identifier indicating the beginning of the padding element (for example, an identifier id synele having the value Oxb, according to Table 4.85 of the AAC MPEG4 standard), and padding data after the identifier, while the padding data includes at least one flag a flag identifying whether enhanced spectrum band replication (eSBR) processing should be performed on the audio content of the block (eg, using spectrum band replication data and eSBR metadata included in the block).

The flag is the eSBR metadata, and an example of a flag is the sbrPatchingMode flag. Another example of a flag feature is the harmonic SBR flag. Both of these flags indicate whether a basic form of spectrum band replication or an advanced form of spectrum replication should be performed on the block's audio data. The basic form of spectrum replication is spectral pasting, and an improved form of spectrum band replication is harmonic transposition.

In some embodiments, the padding data also includes additional eSBR metadata (ie, eSBR metadata other than a flag).

The memory may be a buffer memory (eg, an implementation of buffer 201 of FIG. 4) that stores (eg, in a non-ephemeral manner) at least one block of the encoded audio bitstream.

It is estimated that the complexity of performing eSBR processing (using harmonic transposition and eSBR pre-equalization) by an eSBR decoder at the time of decoding an MPEG-4 AAC bitstream that includes eSBR metadata (indicating these eSBR facilities) would be as follows (for a typical decoding with the specified parameters):

harmonic transposition (16 kbps, 14400/28800 Hz) based on DFT: 3.68 WMOPS (weighted million operations per second);

based on KZF: 0.98 WMOPS;

gluing pre-treatment with KZF (pre-alignment): 0.1 WMOPS.

It is known that DFT-based transposition typically performs better than CFP-based transposition for transients.

In accordance with some embodiments of the present invention, a pad element (of an encoded audio bitstream) that includes eSBR metadata also includes a parameter (eg, bs_extension_id parameter) whose value (eg, bs_extension_id=3) signals that the eSBR metadata included in the fill element and that eSBR processing should be performed on the audio content of the relevant block, and/or a parameter (eg, the same bs_extension_id parameter whose value (eg, bs_extension_id=2) signals that the fill element's sbr_extension() container includes in PS data itself, For example, as indicated in Table 1 below, such a parameter having the value bs_extension_id=2 can signal that the sbr_extension() container of the fill element includes PS data, and such a parameter having the value bs_extension_id=3 , may signal that the infill element's sbr_extension() container includes eSBR metadata .

Table 1

bs_extension_id Meaning 0 reserved 1 reserved 2 EXTENSION_ID_PS 3 EXTENSION_ID_ESBR

In accordance with some embodiments of the invention, the syntax of each spectrum band replication extension element that includes eSBR metadata and/or PS data is as indicated in Table 1. 2 above (in which sbr_extension() denotes a container that is a spectrum band replication extension member, bs_extension_id is as described in Table 1 above, ps_data denotes PS data, and esbr_data denotes eSBR metadata).

table 2

sbr_extension(bs_extension_id, num_bits_left) { switch (bs_extension_id) { case EXTENSION_ID_PS: num_bits_left -= ps_data(); Note 1 break; case EXTENSION_ID_ESBR: num_bits_left -= esbr_data(); Note 2 break; default: bs_f i1l_bi ts; num_bits_left=0; break; } } Note 1: ps_data() returns the number of bits read. Note 2: esbr_data() returns the number of bits read.

- 12040874

In an exemplary embodiment, esbr_data(), mentioned in the table. 2 above is indicating the values of the following metadata parameters:

1) a one-bit metadata parameter, bs_sbr_preprocessing; And

2) for each channel (ch) of the audio content of the encoded bitstream to be decoded, each of the parameters described above:

sbrPatchingMode[ch]; sbrOversamplingFlag[ch]; sbrPitchInBinsFlag[ch]; and sbrPitchInBins[ch].

For example, in some embodiments, esbr_data() may have the syntax shown in Table. 3 to indicate these metadata options.

Table 3

Syntax Number of bits esbr_data(id_aac, bs_coupling) { bs_sbr_preprocessing; 1 if (id_aac == ID_SCE) { if (sbrPatchingMode[0] == 0) { 1 sbrOversamplingFlag[0]; 1 if (sbrPitchInBinsFlag[0]) 1 sbrPitchInBins[0]; 7 else sbrPitchInBins[0]=0; } else { sbrOversamplingFlag[0]=0; sbrPitchInBins[0]=0; }

- 13 040874

} else if (id_aac == ID_CPE) { If (bs_coupling) { if (sbrPatchingMode[0,1] == 0) { 1 sbrOversamplingFlag[0,1]; 1 if (sbrPitchlnBinsFlag[0,1]) 1 sbrPitchInBins[0,1]; 7 else sbrPitchInBins[0,1]=0; } else { sbrOversamplingFlag[0,1]=0; sbrPitchInBins[0,1]=0; } } else { /* bs_coupling == 0 */ if (sbrPatchingMode[0] == 0) { 1 sbrOversamplingFlag[0]; 1 if (sbrPitchlnBinsFlag[0] ) 1 sbrPitchInBins[0] ; 7 else sbrPitchInBins[0]=0; } else { sbrOversamplingFlag[0]=0; sbrPitchInBins[0]=0; } if (sbrPatchingMode[1] == 0) { 1 sbrOversamplingFlag[1]; 1 if (sbrPitchlnBinsFlag[1]) 1 sbrPitchInBins[1]; 7 else sbrPitchInBins[1]=0; } else { sbrOversamplingFlag[1]=0; sbrPitchInBins[1]=0; } } } } Note: bs_sbr_preprocessing is defined as described in section 6.2.12 of ISO/IEC 23003-3:2012. sbrPatchingMode[ch], sbrOversamplingFlag[ch] , sbrPitchlnBinsFlag[ch] and sbrPitchlnBins[ch] are defined as described in section 7.5 of ISO/IEC 23003-3:2012.

The above syntax allows a rational implementation of an advanced form of spectrum band replication, such as harmonic transposition, as an extension of a legacy decoder. More precisely, the eSBR data from Table. 3 include only those parameters needed to perform an advanced form of spectrum band replication that are not yet supported in the bitstream and are not directly derived from the parameters already supported in the bitstream. All other parameters and processing data needed to perform an advanced form of spectrum band replication are derived from pre-existing parameters at already defined locations in the bitstream.

- 14040874

For example, a HE-AAC MPEG-4 or HE-AAC v2 compatible decoder can be extended to include an advanced form of spectrum band replication such as harmonic transposition. This advanced form of spectrum band replication is in addition to the basic form of spectrum band replication already supported by the decoder. In the context of a HEAAC or HE-AAC v2 MPEG-4 compliant decoder, this basic form of spectrum band replication is the means of SBR spectral embedding with CFP as defined in section 4.6.18 of the AAC MPEG4 standard.

When performing an advanced form of spectrum band replication, an extended HE-AAC decoder can reuse many of the bitstream parameters already included in the SBR extension payload of the bitstream. Specific parameters that can be reused include, for example, various parameters that define a summary table of frequency bands. These parameters include bs_start_freq (a parameter that specifies the start of the frequency summary table parameter), bs_stop_freq (a parameter that specifies the end of the summary frequency table), bs_freq_scale (a parameter that specifies the number of frequency bands per octave), and bs_alter_scale (a parameter that changes the scale frequency bands). The parameters that can be reused also include parameters that define a noise band table (bs_noise_bands) and limit band table parameters (bs_limiter_bands). Accordingly, in various embodiments, at least some of the equivalent parameters specified in the USAC standard are not included in the bitstream, thereby reducing overhead and control data in the bitstream. Typically, in cases where a parameter specified in the AAC standard has an equivalent parameter specified in USAC, the equivalent parameter specified in USAC has the same name as the parameter specified in the AAC standard, for example, envelope scaling factor, E _Or i _gMapped . However, the equivalent parameter defined in the USAC standard typically has a different value that is adapted to handle the advanced SBR defined in the USAC standard rather than the processing of the SBR defined in the AAC standard.

In addition to numerous parameters, other data elements may also be reused by the extended HE-AAC decoder when performing an advanced form of spectrum band replication in accordance with embodiments of the invention. For example, envelope data and noise floor data can also be extracted from bs data env (envelope scale factors) and bs_noise_env (noise floor scale factors) data and used during an advanced form of spectrum band replication.

As such, these embodiments use the configuration parameters and envelope data already supported by the legacy HE-AAC or HE-AAC v2 decoder in the SBR extension payload to enable an advanced form of spectrum band replication while requiring as little additional transmission data as possible. The metadata was originally adapted for a basic form of HFR (eg, spectral embedding of SBR), but, in accordance with embodiments, is used for an advanced form of HFR (eg, harmonic transposition of eSBR). As discussed earlier, the metadata is typically operating parameters (e.g., envelope scaling factors, noise floor scaling factors, time/grid parameters, sinusoidal complement information, variable frequency/crossover bandwidth, inverse filtering mode, envelope resolution, smoothing mode, frequency interpolation mode). adapted and intended for use with the basic form of HFR (eg linear transformation). However, this metadata, combined with additional metadata parameters specific to the advanced form of HFR (eg, harmonic transposition), can be used to rationally and efficiently process audio data using the advanced form of HFR.

Accordingly, extended decoders that support an advanced form of spectrum band replication can be created in a very efficient manner by relying on already defined bitstream elements (eg, those in the SBR extension payload) and adding only those parameters necessary to support the advanced form of band replication. spectrum (in the padding element extension payload). This data reduction feature, combined with placing newly added parameters in reserved data fields such as an extension container, greatly reduces the barriers to building a decoder that supports advanced spectrum band replication, ensuring that the bitstream is backwards compatible with a legacy decoder that does not support advanced form. replication bands of the spectrum.

In table. 3, the number in the right column indicates the number of bits of the corresponding parameter in the left column.

In some embodiments, the SBR object type defined in MPEG-4 AAC has been updated to contain the SBR facility or enhanced SBR facility (eSBR) aspects as signaled in the SBR extension element (bs_extension_id== EXTENSION_ID_ESBR).

In some embodiments, the invention is a method including the step

- 15 040874 encoding audio data to generate an encoded bitstream (for example, an MPEG-4 AAC bitstream), including by including eSBR metadata in at least one segment of at least one encoded bitstream block and audio data in at least one other block segment. In exemplary embodiments, the method includes the step of multiplexing audio data with eSBR metadata in each encoded bitstream block. In a typical decoding of an encoded bitstream in an eSBR decoder, the decoder extracts the eSBR metadata from the bitstream (including by parsing and demultiplexing the eSBR metadata and audio data) and uses the eSBR metadata to process the audio data to generate a decoded audio data stream.

Yet another aspect of the invention is an eSBR decoder configured to perform eSBR processing (e.g., using at least one of the eSBR tools known as harmonic transposition or pre-equalization) during decoding of an encoded audio stream (e.g., an AAC MPEG-4 bitstream ) that does not include eSBR metadata. An example of such a decoder will be described with reference to FIG. 5.

The eSBR decoder (400) of FIG. 5 includes a buffer memory 201 (which is identical to the memory 201 of FIGS. 3 and 4), a bitstream payload deformer 215 (which is identical to the deformer 215 of FIG. 4), an audio signal decoding subsystem 202 (sometimes referred to as the main decoding stage or main decoding subsystem, and which is identical to main decoding subsystem 202 of Fig. 3), an eSBR control data generation subsystem 401, and an eSBR processing stage 203 (which is identical to stage 203 of Fig. 3, connected as shown. Also, typically, decoder 400 includes other processing elements (not shown).

In operation of the decoder 400, a block sequence of the encoded audio bitstream (MPEG-4 AAC bitstream) received by the decoder 400 is presented from the buffer 201 to the deformer 215.

A deformer 215 is attached and configured to demultiplex each block of the bitstream to extract SBR metadata (including quantized envelope data) and typically other metadata from it as well. The deformer 215 is configured to add at least SBR metadata to the eSBR processing stage 203 . A deformer 215 is also attached and configured to extract audio data from each block of the bitstream, and present the extracted audio data to a decoding subsystem 202 (decoding stage).

The audio decoding subsystem 202 of the decoder 400 is configured to decode the audio data extracted by the deformer 215 (such decoding may be referred to as a main decoding operation) to generate decoded audio data and provide the decoded audio data to the eSBR processing stage 203 . The decoding is performed in the frequency domain. Typically, the final processing stage in subsystem 202 applies a frequency-domain-to-time-domain transform to the decoded frequency-domain audio data such that the output of the subsystem is the decoded time-domain audio data. The stage 203 is configured to apply the SBRs (and the eSBRs) indicated by the SBR metadata (extracted by the deformer 215) and the eSBR metadata generated in the subsystem 401 to the decoded audio data (i.e., perform SBR and eSBR processing on the output of the decoding subsystem 202 with using SBR and eSBR metadata) to generate fully decoded audio data that is output from decoder 400. Typically, decoder 400 includes memory (accessible from subsystem 202 and stage 203) that stores deformed audio data and metadata output from decoder 215 ( and optionally also subsystems 401), and stage 203 is configured to access audio data and metadata as needed during SBR and eSBR processing. The SBR processing at stage 203 may be considered post-processing at the output of main decoding subsystem 202. Optionally, decoder 400 also includes a post-upmix subsystem (which can apply Parametric Stereo (PS) facilities defined in the MPEG-4 AAC standard using PS metadata extracted by deformer 215) that is coupled to and configured to perform upmixing. mixing over the output of stage 203 to generate a fully decoded upmixed audio signal that is output from APU 210.

The control data generation subsystem 401 of FIG. 5 is attached and configured to detect at least one property of the encoded audio bitstream to be decoded and generate eSBR control data (which may be or include eSBR metadata of any of the types included in the encoded audio bitstreams, in accordance with others embodiments of the invention) in response to at least one result of the detection step. The eSBR control data is added to the cascade 203 to trigger the application of individual eSBRs or a combination of eSBRs upon detection of a particular property (or combination of properties) of the bitstream and/or control the application of such eSBRs. For example, in order to control the execution of eSBR processing using harmonic

- 16 040874 transposition, some embodiments of the subsystem 401 generation of control data would include: a music detector (for example, a simplified version of the traditional music detector) for setting the parameter sbrPatchingMode[ch] (and presenting the set parameter to the cascade 203) in response to detection, that the bitstream is or is not indicative of music; a transient detector for setting a parameter sbrOversamplingFlag[ch] (and presenting the set parameter to stage 203) in response to detecting the presence or absence of transients in the audio content indicated by the bitstream; and/or a pitch detector for setting parameters sbrPitchInBinsFlag[ch] and sbrPitchInBins[ch] (and providing the set parameters to stage 203) in response to detecting the pitch of the audio content indicated by the bitstream. Other aspects of the invention are methods for decoding an audio bitstream performed by any embodiment of the inventive decoder described in this paragraph and the previous paragraph.

Aspects of the invention include a method for encoding or decoding the type that any embodiment of an inventive APU, system, or device is configured (or programmed) to perform. Other aspects of the invention include a system or device capable of (e.g., programmed) to execute any embodiment of the inventive method, and a machine-readable medium (e.g., a disk) that stores a computer program (e.g., in a non-ephemeral manner) to implement any embodiment of the inventive method or steps thereof. For example, an inventive system may be or include a general purpose programmable processor, digital signal processor, or microprocessor programmed with software or firmware and/or otherwise configured to perform any of a variety of operations on data, including, carrying out the inventive method or steps thereof. Such a general purpose processor may be or include a computer system including input device, memory, processing circuitry programmed (and/or otherwise configured) to execute an embodiment of the inventive method (or steps thereof) in response to information provided to him.

Embodiments of the present invention may be implemented in hardware, firmware, or software, or a combination of both (eg, as a programmable logic array). Unless otherwise specified, the algorithms and processes included as part of the invention are, by their nature, not related to any particular computer or other device. In particular, various general purpose machines may be used with programs written in accordance with the teachings of the present invention, or it may be more convenient to construct a more specialized device (eg, integrated circuits) to perform the required method steps. Thus, the invention may be implemented in one or more computer programs executing on one or more programmable computer systems (e.g., an implementation of any of the elements of FIG. 1 or the encoder 100 of FIG. 2 (or an element thereof), or the decoder 200 of Fig. 3 (or its element), or decoder 210 according to Fig. 4 (or its element) or decoder 400 according to Fig. 5 (or its element)), each of which contains at least one processor, at least one system data storage (including volatile or non-volatile memory elements and/or storage elements), at least one input device or port, and at least one output device or port. The control program is applied to the input data to perform the functions described in the materials of the present invention, and generates output information. The output information is sent to one or more output devices in a known manner.

Each such program may be implemented in any desired computer language (including machine, layout, or high-level procedural, logical, or object-oriented programming languages) for communicating with a computer system. In any case, the language may be a compiled language or an interpreted language.

For example, when implemented by computer software instruction sequences, the various functions and steps of embodiments of the invention may be implemented by multi-threaded software instruction sequences running on suitable digital signal processing hardware, in which case, the various devices, steps, and functions of the embodiments may correspond to instruction chunks. software.

Each such computer program is preferably stored on or loaded onto storage media or a device (e.g., solid-state memory or media, or magnetic or optical media) readable by a general purpose or special purpose programmable computer for configuring and controlling the computer when the storage media or device are read by a computer system to carry out the procedures described in the materials of the present invention. The inventive system may also be implemented as a computer-readable storage medium configured by a computer program (i.e., storing the computer program), wherein the storage medium thus configured causes the computer system to act in a specific and predetermined manner to perform functions. described in the materials of the present invention.

A number of embodiments of the invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. For example, in order to facilitate efficient implementations, phase shifts can be used in combination with signal decomposition and signal synthesis filterbanks by a complex FPS. The signal decomposition filterbank is responsible for filtering the time-domain low-band signal generated by the main decoder into a plurality of subbands (eg, QDF subbands). The signal decomposition filterbank is responsible for combining the reconstructed high frequency band created by the selected HFR technology (as indicated by the received sbrPatchingMode parameter) with the decoded low frequency band to synthesize a wideband audio output signal. A given filter bank implementation operating in a particular sampling rate mode, such as normal double-rate operation or downsampling SBR, however, shall not have phase shifts that are bitstream dependent. The KZF combs used in SBR are an extension of the complex exponential function of cosine filter comb theory. It can be shown that spurious suppression limitations become obsolete when the cosine wave filter bank is expanded with complex exponential modulation. Thus, with respect to the combs from the SBR FKF, both the signal decomposition filters, h _k (n), and the signal synthesis filters, f _k (n), can be defined by ^h k^ = fk^ = Po^ ⁺ - Tj <n<N; 0 <k< M ₍₁₎ where p ₀ (n) is a real-valued symmetric or non-symmetric prototype filter (typically a prototype low-pass filter), M denotes the number of channels, and N is the order of the prototype filter. The number of channels used in the signal decomposition filterbank may be different from the number of channels used in the signal synthesis filterbank. For example, a signal decomposition filterbank may have 32 channels, and a signal synthesis filterbank may have 64 channels. When operating the signal synthesis filterbank in downsampling mode, the signal synthesis filterbank can only have 32 channels. Because the subband samples from the filterbank are complex-valued, an additive possibly channel dependent phase shift stage can be added to the signal decomposition filterbank. These additional phase shifts must be compensated for before the signal synthesis filter bank. Despite the fact that the elements of the phase shift can in principle be arbitrary values that do not disrupt the operation of the signal decomposition / synthesis chain using the FPC, they can also be limited to certain values for compliance control. The SBR signal will be influenced by the choice of phase factors, while the low pass signal coming from the main decoder will not. The sound quality of the output signal is not affected.

The prototype filter coefficients, p ₀ (n), can be limited to a length, L, of 640, as shown in Table 1. 4 below.

- 18 040874

Table 4

η ro (η) η ρο(η) η ρο(η) 0 0.0000000000 214 0.0019765601 428 0.0117623832 1 -0.0005525286 215 -0.0032086896 429 0.0163701258 2 -0.0005617692 216 -0.0085711749 430 0.0207997072 3 -0.0004947518 217 -0.0141288827 431 0.0250307561 4 -0.0004875227 218 -0.0198834129 432 0.0290824006 5 -0.0004893791 219 -0.0258227288 433 0.0329583930 6 -0.0005040714 220 -0.0319531274 434 0.0366418116 7 -0.0005226564 221 -0.0382776572 435 0.0401458278 8 -0.0005466565 222 -0.0447806821 436 0.0434768782 9 -0.0005677802 223 -0.0514804176 437 0.0466303305 10 -0.0005870930 224 -0.0583705326 438 0.0495978676 eleven -0.0006132747 225 -0.0654409853 439 0.0524093821 12 -0.0006312493 226 -0.0726943300 440 0.0550460034 13 -0.0006540333 227 -0.0801372934 441 0.0575152691 14 -0.0006777690 228 -0.0877547536 442 0.0598166570 15 -0.0006941614 229 -0.0955533352 443 0.0619602779 16 -0.0007157736 230 -0.1035329531 444 0.0639444805 17 -0.0007255043 231 -0.1116826931 445 0.0657690668 18 -0.0007440941 232 -0.1200077984 446 0.0674525021 19 -0.0007490598 233 -0.1285002850 447 0.0689664013 20 -0.0007681371 234 -0.1371551761 448 0.0703533073 21 -0.0007724848 235 -0.1459766491 449 0.0715826364 22 -0.0007834332 236 -0.1549607071 450 0.0726774642

- 19 040874

23 -0.0007779869 237 -0.1640958855 451 0.0736406005 24 -0.0007803664 238 -0.1733808172 452 0.0744664394 25 -0.0007801449 239 -0.1828172548 453 0.0751576255 26 -0.0007757977 240 -0.1923966745 454 0.0757305756 27 -0.0007630793 241 -0.2021250176 455 0.0761748321 28 -0.0007530001 242 -0.2119735853 456 0.0765050718 29 -0.0007319357 243 -0.2219652696 457 0.0767204924 thirty -0.0007215391 244 -0.2320690870 458 0.0768230011 31 -0.0006917937 245 -0.2423016884 459 0.0768173975 32 -0.0006650415 246 -0.2526480309 460 0.0767093490 33 -0.0006341594 247 -0.2631053299 461 0.0764992170 34 -0.0005946118 248 -0.2736634040 462 0.0761992479 35 -0.0005564576 249 -0.2843214189 463 0.0758008358 36 -0.0005145572 250 -0.2950716717 464 0.0753137336 37 -0.0004606325 251 -0.3059098575 465 0.0747452558 38 -0.0004095121 252 -0.3168278913 466 0.0741003642 39 -0.0003501175 253 -0.3278113727 467 0.0733620255 40 -0.0002896981 254 -0.3388722693 468 0.0725682583 41 -0.0002098337 255 -0.3499914122 469 0.0717002673 42 -0.0001446380 256 0.3611589903 470 0.0707628710 43 -0.0000617334 257 0.3723795546 471 0.0697630244 44 0.0000134949 258 0.3836350013 472 0.0687043828 45 0.0001094383 259 0.3949211761 473 0.0676075985 46 0.0002043017 260 0.4062317676 474 0.0664367512 47 0.0002949531 261 0.4175696896 475 0.0652247106 48 0.0004026540 262 0.4289119920 476 0.0639715898 49 0.0005107388 263 0.4402553754 477 0.0626857808 50 0.0006239376 264 0.4515996535 478 0.0613455171 51 0.0007458025 265 0.4629308085 479 0.0599837480 52 0.0008608443 266 0.4742453214 480 0.0585915683 53 0.0009885988 267 0.4855253091 481 0.0571616450 54 0.0011250155 268 0.4967708254 482 0.0557173648 55 0.0012577884 269 0.5079817500 483 0.0542452768 56 0.0013902494 270 0.5191234970 484 0.0527630746

- 20 040874

57 0.0015443219 271 0.5302240895 485 0.0512556155 58 0.0016868083 272 0.5412553448 486 0.0497385755 59 0.0018348265 273 0.5522051258 487 0.0482165720 60 0.0019841140 274 0.5630789140 488 0.0466843027 61 0.0021461583 275 0.5738524131 489 0.0451488405 62 0.0023017254 276 0.5845403235 490 0.0436097542 63 0.0024625616 277 0.5951123086 491 0.0420649094 64 0.0026201758 278 0.6055783538 492 0.0405349170 65 0.0027870464 279 0.6159109932 493 0.0390053679 66 0.0029469447 280 0.6261242695 494 0.0374812850 67 0.0031125420 281 0.6361980107 495 0.0359697560 68 0.0032739613 282 0.6461269695 496 0.0344620948 69 0.0034418874 283 0.6559016302 497 0.0329754081 70 0.0036008268 284 0.6655139880 498 0.0315017608 71 0.0037603922 285 0.6749663190 499 0.0300502657 72 0.0039207432 286 0.6842353293 500 0.0286072173 73 0.0040819753 287 0.6933282376 501 0.0271859429 74 0.0042264269 288 0.7022388719 502 0.0257875847 75 0.0043730719 289 0.7109410426 503 0.0244160992 76 0.0045209852 290 0.7194462634 504 0.0230680169 77 0.0046606460 291 0.7277448900 505 0.0217467550 78 0.0047932560 292 0.7358211758 506 0.0204531793 79 0.0049137603 293 0.7436827863 507 0.0191872431 80 0.0050393022 294 0.7513137456 508 0.0179433381 81 0.0051407353 295 0.7587080760 509 0.0167324712 82 0.0052461166 296 0.7658674865 510 0.0155405553 83 0.0053471681 297 0.7727780881 511 0.0143904666 84 0.0054196775 298 0.7794287519 512 -0.0132718220 85 0.0054876040 299 0.7858353120 513 -0.0121849995 86 0.0055475714 300 0.7919735841 514 -0.0111315548 87 0.0055938023 301 0.7978466413 515 -0.0101150215 88 0.0056220643 302 0.8034485751 516 -0.0091325329 89 0.0056455196 303 0.8087695004 517 -0.0081798233 90 0.0056389199 304 0.8138191270 518 -0.0072615816

- 21 040874

91 0.0056266114 305 0.8185776004 519 -0.0063792293 92 0.0055917128 306 0.8230419890 520 -0.0055337211 93 0.0055404363 307 0.8272275347 521 -0.0047222596 94 0.0054753783 308 0.8311038457 522 -0.0039401124 95 0.0053838975 309 0.8346937361 523 -0.0031933778 96 0.0052715758 310 0.8379717337 524 -0.0024826723 97 0.0051382275 311 0.8409541392 525 -0.0018039472 98 0.0049839687 312 0.8436238281 526 -0.0011568135 99 0.0048109469 313 0.8459818469 527 -0.0005464280 100 0.0046039530 314 0.8480315777 528 0.0000276045 101 0.0043801861 315 0.8497805198 529 0.0005832264 102 0.0041251642 316 0.8511971524 530 0.0010902329 103 0.0038456408 317 0.8523047035 531 0.0015784682 104 0.0035401246 318 0.8531020949 532 0.0020274176 105 0.0032091885 319 0.8535720573 533 0.0024508540 106 0.0028446757 320 0.8537385600 534 0.0028446757 107 0.0024508540 321 0.8535720573 535 0.0032091885 108 0.0020274176 322 0.8531020949 536 0.0035401246 109 0.0015784682 323 0.8523047035 537 0.0038456408 110 0.0010902329 324 0.8511971524 538 0.0041251642 111 0.0005832264 325 0.8497805198 539 0.0043801861 112 0.0000276045 326 0.8480315777 540 0.0046039530 113 -0.0005464280 327 0.8459818469 541 0.0048109469 114 -0.0011568135 328 0.8436238281 542 0.0049839687 115 -0.0018039472 329 0.8409541392 543 0.0051382275 116 -0.0024826723 330 0.8379717337 544 0.0052715758 117 -0.0031933778 331 0.8346937361 545 0.0053838975 118 -0.0039401124 332 0.8311038457 546 0.0054753783 119 -0.0047222596 333 0.8272275347 547 0.0055404363 120 -0.0055337211 334 0.8230419890 548 0.0055917128 121 -0.0063792293 335 0.8185776004 549 0.0056266114 122 -0.0072615816 336 0.8138191270 550 0.0056389199 123 -0.0081798233 337 0.8087695004 551 0.0056455196 124 -0.0091325329 338 0.8034485751 552 0.0056220643

- 22 040874

125 -0.0101150215 339 0.7978466413 553 0.0055938023 126 -0.0111315548 340 0.7919735841 554 0.0055475714 127 -0.0121849995 341 0.7858353120 555 0.0054876040 128 0.0132718220 342 0.7794287519 556 0.0054196775 129 0.0143904666 343 0.7727780881 557 0.0053471681 130 0.0155405553 344 0.7658674865 558 0.0052461166 131 0.0167324712 345 0.7587080760 559 0.0051407353 132 0.0179433381 346 0.7513137456 560 0.0050393022 133 0.0191872431 347 0.7436827863 561 0.0049137603 134 0.0204531793 348 0.7358211758 562 0.0047932560 135 0.0217467550 349 0.7277448900 563 0.0046606460 136 0.0230680169 350 0.7194462634 564 0.0045209852 137 0.0244160992 351 0.7109410426 565 0.0043730719 138 0.0257875847 352 0.7022388719 566 0.0042264269 139 0.0271859429 353 0.6933282376 567 0.0040819753 140 0.0286072173 354 0.6842353293 568 0.0039207432 141 0.0300502657 355 0.6749663190 569 0.0037603922 142 0.0315017608 356 0.6655139880 570 0.0036008268 143 0.0329754081 357 0.6559016302 571 0.0034418874 144 0.0344620948 358 0.6461269695 572 0.0032739613 145 0.0359697560 359 0.6361980107 573 0.0031125420 146 0.0374812850 360 0.6261242695 574 0.0029469447 147 0.0390053679 361 0.6159109932 575 0.0027870464 148 0.0405349170 362 0.6055783538 576 0.0026201758 149 0.0420649094 363 0.5951123086 577 0.0024625616 150 0.0436097542 364 0.5845403235 578 0.0023017254 151 0.0451488405 365 0.5738524131 579 0.0021461583 152 0.0466843027 366 0.5630789140 580 0.0019841140 153 0.0482165720 367 0.5522051258 581 0.0018348265 154 0.0497385755 368 0.5412553448 582 0.0016868083 155 0.0512556155 369 0.5302240895 583 0.0015443219 156 0.0527630746 370 0.5191234970 584 0.0013902494 157 0.0542452768 371 0.5079817500 585 0.0012577884 158 0.0557173648 372 0.4967708254 586 0.0011250155

- 23 040874

159 0.0571616450 373 0.4855253091 587 0.0009885988 160 0.0585915683 374 0.4742453214 588 0.0008608443 161 0.0599837480 375 0.4629308085 589 0.0007458025 162 0.0613455171 376 0.4515996535 590 0.0006239376 163 0.0626857808 377 0.4402553754 591 0.0005107388 164 0.0639715898 378 0.4289119920 592 0.0004026540 165 0.0652247106 379 0.4175696896 593 0.0002949531 166 0.0664367512 380 0.4062317676 594 0.0002043017 167 0.0676075985 381 0.3949211761 595 0.0001094383 168 0.0687043828 382 0.3836350013 596 0.0000134949 169 0.0697630244 383 0.3723795546 597 -0.0000617334 170 0.0707628710 384 -0.3611589903 598 -0.0001446380 171 0.0717002673 385 -0.3499914122 599 -0.0002098337 172 0.0725682583 386 -0.3388722693 600 -0.0002896981 173 0.0733620255 387 -0.3278113727 601 -0.0003501175 174 0.0741003642 388 -0.3168278913 602 -0.0004095121 175 0.0747452558 389 -0.3059098575 603 -0.0004606325 176 0.0753137336 390 -0.2950716717 604 -0.0005145572 177 0.0758008358 391 -0.2843214189 605 -0.0005564576 178 0.0761992479 392 -0.2736634040 606 -0.0005946118 179 0.0764992170 393 -0.2631053299 607 -0.0006341594 180 0.0767093490 394 -0.2526480309 608 -0.0006650415 181 0.0768173975 395 -0.2423016884 609 -0.0006917937 182 0.0768230011 396 -0.2320690870 610 -0.0007215391 183 0.0767204924 397 -0.2219652696 611 -0.0007319357 184 0.0765050718 398 -0.2119735853 612 -0.0007530001 185 0.0761748321 399 -0.2021250176 613 -0.0007630793 186 0.0757305756 400 -0.1923966745 614 -0.0007757977 187 0.0751576255 401 -0.1828172548 615 -0.0007801449 188 0.0744664394 402 -0.1733808172 616 -0.0007803664 189 0.0736406005 403 -0.1640958855 617 -0.0007779869 190 0.0726774642 404 -0.1549607071 618 -0.0007834332 191 0.0715826364 405 -0.1459766491 619 -0.0007724848 192 0.0703533073 406 -0.1371551761 620 -0.0007681371

Claims (8)

193 0.0689664013 407 -0.1285002850 621 -0.0007490598 194 0.0674525021 408 -0.1200077984 622 -0.0007440941 195 0.0657690668 409 -0.1116826931 623 -0.0007255043 196 0.0639444805 410 -0.1035329531 624 -0.0007157736 197 0.0619602779 411 -0.0955533352 625 -0.0006941614 198 0.0598166570 412 -0.0877547536 626 -0.0006777690 199 0.0575152691 413 -0.0801372934 627 -0.0006540333 200 0.0550460034 414 -0.0726943300 628 -0.0006312493 201 0.0524093821 415 -0.0654409853 629 -0.0006132747 202 0.0495978676 416 -0.0583705326 630 -0.0005870930 203 0.0466303305 417 -0.0514804176 631 -0.0005677802 204 0.0434768782 418 -0.0447806821 632 -0.0005466565 205 0.0401458278 419 -0.0382776572 633 -0.0005226564 206 0.0366418116 420 -0.0319531274 634 -0.0005040714 207 0.0329583930 421 -0.0258227288 635 -0.0004893791 208 0.0290824006 422 -0.0198834129 636 -0.0004875227 209 0.0250307561 423 -0.0141288827 637 -0.0004947518 210 0.0207997072 424 -0.0085711749 638 -0.0005617692 211 0.0163701258 425 -0.0032086896 639 -0.0005525280 212 0.0117623832 426 0.0019765601 213 0.0069636862 427 0.0069636862 The prototype filter, p0(n), may also be derived from Table 4 through one or more mathematical operations such as rounding, downsampling, interpolation, or decimation. It is understood that, within the scope of the appended claims, the invention may be practiced in a manner other than specifically described in the materials of the present invention. Any reference numbers contained in the following claims are for illustrative purposes only and should not be used in any way to interpret or limit the claims. CLAIM 1. A method for decoding an encoded audio bitstream, the method comprises receiving an encoded audio bitstream, the encoded audio bitstream includes audio data constituting a low band portion of an audio signal, wherein the encoded audio bitstream also includes the padding element itself with an identifier indicating the start of the padding element and padding data after the identifier; decoding the audio data to generate a decoded audio signal in the low band; extracting high frequency reconstruction metadata from the encoded audio bitstream, the high frequency reconstruction metadata includes operating parameters for a high frequency reconstruction process that linearly transforms a consecutive number of subbands from a low frequency band portion of an audio signal to a high frequency band portion of an audio signal; filtering the decoded lowband audio signal with a signal decomposition filterbank to generate a filtered lowband audio signal; extracting from the encoded audio bitstream a parameter indicating whether or not to use an adaptive frequency domain with respect to the resampling signal; extracting from the encoded audio bitstream a flag pointer indicating whether a linear transformation or harmonic transposition should be performed on the audio data; restoring a portion of the high frequency band of the audio signal using the filtered low band audio signal and high frequency reconstruction metadata according to the flag pointer; and combining the filtered low band audio signal and the reconstructed high band portion to form a wideband audio signal, wherein the signal decomposition filterbank includes signal decomposition filters, ht(n), which are modulated versions of the prototype filter, po(n) , according to -25 040874 h _k (n) = p _Q (n) exp* L/ 1V 'm[ ^{to +} 2 Ju ijj 0<n<N-,0<k<M where p ₀ (n) is a real-valued symmetric or non-symmetric prototype filter, M is the number of channels in the signal decomposition filter bank, and N is the order of the prototype filter. 2. The method of claim 1, wherein the high frequency reconstruction metadata includes an operating parameter selected from the group consisting of envelope scale factors, noise level scale factors, sinusoidal complement information, time/frequency grid information, crossover frequency. and reverse filtering mode. 3. The method according to claim 1, in which the prototype filter, p0(n), is derived from the coefficients in table. 4 below: N ro(p) N ro(p) η ro(p) 0 0.0000000000 214 0.0019765601 428 0.0117623832 1 -0.0005525286 215 -0.0032086896 429 0.0163701258 2 -0.0005617692 216 -0.0085711749 430 0.0207997072 3 -0.0004947518 217 -0.0141288827 431 0.0250307561 4 -0.0004875227 218 -0.0198834129 432 0.0290824006 5 -0.0004893791 219 -0.0258227288 433 0.0329583930 6 -0.0005040714 220 -0.0319531274 434 0.0366418116 7 -0.0005226564 221 -0.0382776572 435 0.0401458278 8 -0.0005466565 222 -0.0447806821 436 0.0434768782 9 -0.0005677802 223 -0.0514804176 437 0.0466303305 10 -0.0005870930 224 -0.0583705326 438 0.0495978676 eleven -0.0006132747 225 -0.0654409853 439 0.0524093821 12 -0.0006312493 226 -0.0726943300 440 0.0550460034 13 -0.0006540333 227 -0.0801372934 441 0.0575152691 14 -0.0006777690 228 -0.0877547536 442 0.0598166570 15 -0.0006941614 229 -0.0955533352 443 0.0619602779 16 -0.0007157736 230 -0.1035329531 444 0.0639444805 - 26 040874 17 -0.0007255043 231 -0.1116826931 445 0.0657690668 18 -0.0007440941 232 -0.1200077984 446 0.0674525021 19 -0.0007490598 233 -0.1285002850 447 0.0689664013 20 -0.0007681371 234 -0.1371551761 448 0.0703533073 21 -0.0007724848 235 -0.1459766491 449 0.0715826364 22 -0.0007834332 236 -0.1549607071 450 0.0726774642 23 -0.0007779869 237 -0.1640958855 451 0.0736406005 24 -0.0007803664 238 -0.1733808172 452 0.0744664394 25 -0.0007801449 239 -0.1828172548 453 0.0751576255 26 -0.0007757977 240 -0.1923966745 454 0.0757305756 27 -0.0007630793 241 -0.2021250176 455 0.0761748321 28 -0.0007530001 242 -0.2119735853 456 0.0765050718 29 -0.0007319357 243 -0.2219652696 457 0.0767204924 thirty -0.0007215391 244 -0.2320690870 458 0.0768230011 31 -0.0006917937 245 -0.2423016884 459 0.0768173975 32 -0.0006650415 246 -0.2526480309 460 0.0767093490 33 -0.0006341594 247 -0.2631053299 461 0.0764992170 34 -0.0005946118 248 -0.2736634040 462 0.0761992479 35 -0.0005564576 249 -0.2843214189 463 0.0758008358 36 -0.0005145572 250 -0.2950716717 464 0.0753137336 37 -0.0004606325 251 -0.3059098575 465 0.0747452558 38 -0.0004095121 252 -0.3168278913 466 0.0741003642 39 -0.0003501175 253 -0.3278113727 467 0.0733620255 40 -0.0002896981 254 -0.3388722693 468 0.0725682583 41 -0.0002098337 255 -0.3499914122 469 0.0717002673 42 -0.0001446380 256 0.3611589903 470 0.0707628710 43 -0.0000617334 257 0.3723795546 471 0.0697630244 44 0.0000134949 258 0.3836350013 472 0.0687043828 45 0.0001094383 259 0.3949211761 473 0.0676075985 46 0.0002043017 260 0.4062317676 474 0.0664367512 47 0.0002949531 261 0.4175696896 475 0.0652247106 48 0.0004026540 262 0.4289119920 476 0.0639715898 49 0.0005107388 263 0.4402553754 477 0.0626857808 50 0.0006239376 264 0.4515996535 478 0.0613455171 -27040874 51 0.0007458025 265 0.4629308085 479 0.0599837480 52 0.0008608443 266 0.4742453214 480 0.0585915683 53 0.0009885988 267 0.4855253091 481 0.0571616450 54 0.0011250155 268 0.4967708254 482 0.0557173648 55 0.0012577884 269 0.5079817500 483 0.0542452768 56 0.0013902494 270 0.5191234970 484 0.0527630746 57 0.0015443219 271 0.5302240895 485 0.0512556155 58 0.0016868083 272 0.5412553448 486 0.0497385755 59 0.0018348265 273 0.5522051258 487 0.0482165720 60 0.0019841140 274 0.5630789140 488 0.0466843027 61 0.0021461583 275 0.5738524131 489 0.0451488405 62 0.0023017254 276 0.5845403235 490 0.0436097542 63 0.0024625616 277 0.5951123086 491 0.0420649094 64 0.0026201758 278 0.6055783538 492 0.0405349170 65 0.0027870464 279 0.6159109932 493 0.0390053679 66 0.0029469447 280 0.6261242695 494 0.0374812850 67 0.0031125420 281 0.6361980107 495 0.0359697560 68 0.0032739613 282 0.6461269695 496 0.0344620948 69 0.0034418874 283 0.6559016302 497 0.0329754081 70 0.0036008268 284 0.6655139880 498 0.0315017608 71 0.0037603922 285 0.6749663190 499 0.0300502657 72 0.0039207432 286 0.6842353293 500 0.0286072173 73 0.0040819753 287 0.6933282376 501 0.0271859429 74 0.0042264269 288 0.7022388719 502 0.0257875847 75 0.0043730719 289 0.7109410426 503 0.0244160992 76 0.0045209852 290 0.7194462634 504 0.0230680169 77 0.0046606460 291 0.7277448900 505 0.0217467550 78 0.0047932560 292 0.7358211758 506 0.0204531793 79 0.0049137603 293 0.7436827863 507 0.0191872431 80 0.0050393022 294 0.7513137456 508 0.0179433381 81 0.0051407353 295 0.7587080760 509 0.0167324712 82 0.0052461166 296 0.7658674865 510 0.0155405553 83 0.0053471681 297 0.7727780881 511 0.0143904666 84 0.0054196775 298 0.7794287519 512 -0.0132718220 - 28 040874 85 0.0054876040 299 0.7858353120 513 -0.0121849995 86 0.0055475714 300 0.7919735841 514 -0.0111315548 87 0.0055938023 301 0.7978466413 515 -0.0101150215 88 0.0056220643 302 0.8034485751 516 -0.0091325329 89 0.0056455196 303 0.8087695004 517 -0.0081798233 90 0.0056389199 304 0.8138191270 518 -0.0072615816 91 0.0056266114 305 0.8185776004 519 -0.0063792293 92 0.0055917128 306 0.8230419890 520 -0.0055337211 93 0.0055404363 307 0.8272275347 521 -0.0047222596 94 0.0054753783 308 0.8311038457 522 -0.0039401124 95 0.0053838975 309 0.8346937361 523 -0.0031933778 96 0.0052715758 310 0.8379717337 524 -0.0024826723 97 0.0051382275 311 0.8409541392 525 -0.0018039472 98 0.0049839687 312 0.8436238281 526 -0.0011568135 99 0.0048109469 313 0.8459818469 527 -0.0005464280 100 0.0046039530 314 0.8480315777 528 0.0000276045 101 0.0043801861 315 0.8497805198 529 0.0005832264 102 0.0041251642 316 0.8511971524 530 0.0010902329 103 0.0038456408 317 0.8523047035 531 0.0015784682 104 0.0035401246 318 0.8531020949 532 0.0020274176 105 0.0032091885 319 0.8535720573 533 0.0024508540 106 0.0028446757 320 0.8537385600 534 0.0028446757 107 0.0024508540 321 0.8535720573 535 0.0032091885 108 0.0020274176 322 0.8531020949 536 0.0035401246 109 0.0015784682 323 0.8523047035 537 0.0038456408 110 0.0010902329 324 0.8511971524 538 0.0041251642 111 0.0005832264 325 0.8497805198 539 0.0043801861 112 0.0000276045 326 0.8480315777 540 0.0046039530 113 -0.0005464280 327 0.8459818469 541 0.0048109469 114 -0.0011568135 328 0.8436238281 542 0.0049839687 115 -0.0018039472 329 0.8409541392 543 0.0051382275 116 -0.0024826723 330 0.8379717337 544 0.0052715758 117 -0.0031933778 331 0.8346937361 545 0.0053838975 118 -0.0039401124 332 0.8311038457 546 0.0054753783 - 29 040874 119 -0.0047222596 333 0.8272275347 547 0.0055404363 120 -0.0055337211 334 0.8230419890 548 0.0055917128 121 -0.0063792293 335 0.8185776004 549 0.0056266114 122 -0.0072615816 336 0.8138191270 550 0.0056389199 123 -0.0081798233 337 0.8087695004 551 0.0056455196 124 -0.0091325329 338 0.8034485751 552 0.0056220643 125 -0.0101150215 339 0.7978466413 553 0.0055938023 126 -0.0111315548 340 0.7919735841 554 0.0055475714 127 -0.0121849995 341 0.7858353120 555 0.0054876040 128 0.0132718220 342 0.7794287519 556 0.0054196775 129 0.0143904666 343 0.7727780881 557 0.0053471681 130 0.0155405553 344 0.7658674865 558 0.0052461166 131 0.0167324712 345 0.7587080760 559 0.0051407353 132 0.0179433381 346 0.7513137456 560 0.0050393022 133 0.0191872431 347 0.7436827863 561 0.0049137603 134 0.0204531793 348 0.7358211758 562 0.0047932560 135 0.0217467550 349 0.7277448900 563 0.0046606460 136 0.0230680169 350 0.7194462634 564 0.0045209852 137 0.0244160992 351 0.7109410426 565 0.0043730719 138 0.0257875847 352 0.7022388719 566 0.0042264269 139 0.0271859429 353 0.6933282376 567 0.0040819753 140 0.0286072173 354 0.6842353293 568 0.0039207432 141 0.0300502657 355 0.6749663190 569 0.0037603922 142 0.0315017608 356 0.6655139880 570 0.0036008268 143 0.0329754081 357 0.6559016302 571 0.0034418874 144 0.0344620948 358 0.6461269695 572 0.0032739613 145 0.0359697560 359 0.6361980107 573 0.0031125420 146 0.0374812850 360 0.6261242695 574 0.0029469447 147 0.0390053679 361 0.6159109932 575 0.0027870464 148 0.0405349170 362 0.6055783538 576 0.0026201758 149 0.0420649094 363 0.5951123086 577 0.0024625616 150 0.0436097542 364 0.5845403235 578 0.0023017254 151 0.0451488405 365 0.5738524131 579 0.0021461583 152 0.0466843027 366 0.5630789140 580 0.0019841140 - 30 040874 153 0.0482165720 367 0.5522051258 581 0.0018348265 154 0.0497385755 368 0.5412553448 582 0.0016868083 155 0.0512556155 369 0.5302240895 583 0.0015443219 156 0.0527630746 370 0.5191234970 584 0.0013902494 157 0.0542452768 371 0.5079817500 585 0.0012577884 158 0.0557173648 372 0.4967708254 586 0.0011250155 159 0.0571616450 373 0.4855253091 587 0.0009885988 160 0.0585915683 374 0.4742453214 588 0.0008608443 161 0.0599837480 375 0.4629308085 589 0.0007458025 162 0.0613455171 376 0.4515996535 590 0.0006239376 163 0.0626857808 377 0.4402553754 591 0.0005107388 164 0.0639715898 378 0.4289119920 592 0.0004026540 165 0.0652247106 379 0.4175696896 593 0.0002949531 166 0.0664367512 380 0.4062317676 594 0.0002043017 167 0.0676075985 381 0.3949211761 595 0.0001094383 168 0.0687043828 382 0.3836350013 596 0.0000134949 169 0.0697630244 383 0.3723795546 597 -0.0000617334 170 0.0707628710 384 -0.3611589903 598 -0.0001446380 171 0.0717002673 385 -0.3499914122 599 -0.0002098337 172 0.0725682583 386 -0.3388722693 600 -0.0002896981 173 0.0733620255 387 -0.3278113727 601 -0.0003501175 174 0.0741003642 388 -0.3168278913 602 -0.0004095121 175 0.0747452558 389 -0.3059098575 603 -0.0004606325 176 0.0753137336 390 -0.2950716717 604 -0.0005145572 177 0.0758008358 391 -0.2843214189 605 -0.0005564576 178 0.0761992479 392 -0.2736634040 606 -0.0005946118 179 0.0764992170 393 -0.2631053299 607 -0.0006341594 180 0.0767093490 394 -0.2526480309 608 -0.0006650415 181 0.0768173975 395 -0.2423016884 609 -0.0006917937 182 0.0768230011 396 -0.2320690870 610 -0.0007215391 183 0.0767204924 397 -0.2219652696 611 -0.0007319357 184 0.0765050718 398 -0.2119735853 612 -0.0007530001 185 0.0761748321 399 -0.2021250176 613 -0.0007630793 186 0.0757305756 400 -0.1923966745 614 -0.0007757977 - 31 040874 187 0.0751576255 401 -0.1828172548 615 -0.0007801449 188 0.0744664394 402 -0.1733808172 616 -0.0007803664 189 0.0736406005 403 -0.1640958855 617 -0.0007779869 190 0.0726774642 404 -0.1549607071 618 -0.0007834332 191 0.0715826364 405 -0.1459766491 619 -0.0007724848 192 0.0703533073 406 -0.1371551761 620 -0.0007681371 193 0.0689664013 407 -0.1285002850 621 -0.0007490598 194 0.0674525021 408 -0.1200077984 622 -0.0007440941 195 0.0657690668 409 -0.1116826931 623 -0.0007255043 196 0.0639444805 410 -0.1035329531 624 -0.0007157736 197 0.0619602779 411 -0.0955533352 625 -0.0006941614 198 0.0598166570 412 -0.0877547536 626 -0.0006777690 199 0.0575152691 413 -0.0801372934 627 -0.0006540333 200 0.0550460034 414 -0.0726943300 628 -0.0006312493 201 0.0524093821 415 -0.0654409853 629 -0.0006132747 202 0.0495978676 416 -0.0583705326 630 -0.0005870930 203 0.0466303305 417 -0.0514804176 631 -0.0005677802 204 0.0434768782 418 -0.0447806821 632 -0.0005466565 205 0.0401458278 419 -0.0382776572 633 -0.0005226564 206 0.0366418116 420 -0.0319531274 634 -0.0005040714 207 0.0329583930 421 -0.0258227288 635 -0.0004893791 208 0.0290824006 422 -0.0198834129 636 -0.0004875227 209 0.0250307561 423 -0.0141288827 637 -0.0004947518 210 0.0207997072 424 -0.0085711749 638 -0.0005617692 211 0.0163701258 425 -0.0032086896 639 -0.0005525280 212 0.0117623832 426 0.0019765601 213 0.0069636862 427 0.0069636862 4. The method according to claim 3, in which the prototype filter, p ₀ (n), is derived from the coefficients in table. 4 through one or more mathematical operations selected from the group consisting of rounding, downsampling, interpolation, or decimation. 5. A non-volatile computer-readable medium containing instructions that, when executed by the processor, cause it to perform the method of claim 1. 6. A decoder for decoding an encoded audio bitstream, the decoder includes an input interface for receiving an encoded audio bitstream, the encoded audio bitstream includes audio data that is part of a low frequency band of an audio signal, and the encoded audio bitstream also includes a padding element with an identifier indicating the start of the padding element and padding data after the identifier; a main decoder for decoding audio data to generate a decoded audio signal in a low band; a parser for extracting, from the encoded audio bitstream, high frequency reconstruction metadata, the high frequency reconstruction metadata includes operating parameters for a high frequency reconstruction process that linearly transforms a successive number of subbands from the low band portion of the audio signal to the high band portion of the audio signal signal; a signal decomposition filter bank for filtering the decoded low-band audio signal to generate a filtered low-band audio signal; a parser for extracting from the encoded audio bitstream a flag pointer indicating whether a linear transformation or a harmonic transposition is to be performed on the audio data, the padding data including the flag pointer; a high frequency restorer for restoring a portion of the high frequency band of the audio signal using the filtered low band audio signal and the high frequency reconstruction metadata according to the flag pointer; and a signal synthesis filter bank for combining the filtered low band audio signal and the reconstructed high band portion to form a wideband audio signal, wherein the signal decomposition filter bank includes signal decomposition filters, h _k (n), which are modulated versions of the prototype filter, p ₀ (n), according to - 32 040874 where p ₀ (n) is a real-valued symmetrical or non-symmetrical prototype filter, M is the number of channels in the signal decomposition filterbank, and N is the order of the prototype filter. 7. The decoder of claim 6, wherein the high frequency reconstruction metadata includes an operating parameter selected from the group consisting of envelope scale factors, noise level scale factors, sinusoidal complement information, time/frequency grid information, crossover frequency. and reverse filtering mode. 8. The decoder according to claim 6, in which the prototype filter, p ₀ (n), is derived from the coefficients in table. 4 below: _____________________________________________________ N ro(p) N ro(p) η ro(p) 0 0.0000000000 214 0.0019765601 428 0.0117623832 1 -0.0005525286 215 -0.0032086896 429 0.0163701258 2 -0.0005617692 216 -0.0085711749 430 0.0207997072 3 -0.0004947518 217 -0.0141288827 431 0.0250307561 4 -0.0004875227 218 -0.0198834129 432 0.0290824006 5 -0.0004893791 219 -0.0258227288 433 0.0329583930 6 -0.0005040714 220 -0.0319531274 434 0.0366418116 7 -0.0005226564 221 -0.0382776572 435 0.0401458278 8 -0.0005466565 222 -0.0447806821 436 0.0434768782 9 -0.0005677802 223 -0.0514804176 437 0.0466303305 10 -0.0005870930 224 -0.0583705326 438 0.0495978676 eleven -0.0006132747 225 -0.0654409853 439 0.0524093821 12 -0.0006312493 226 -0.0726943300 440 0.0550460034 13 -0.0006540333 227 -0.0801372934 441 0.0575152691 14 -0.0006777690 228 -0.0877547536 442 0.0598166570 15 -0.0006941614 229 -0.0955533352 443 0.0619602779 - 33 040874 16 -0.0007157736 230 -0.1035329531 444 0.0639444805 17 -0.0007255043 231 -0.1116826931 445 0.0657690668 18 -0.0007440941 232 -0.1200077984 446 0.0674525021 19 -0.0007490598 233 -0.1285002850 447 0.0689664013 20 -0.0007681371 234 -0.1371551761 448 0.0703533073 21 -0.0007724848 235 -0.1459766491 449 0.0715826364 22 -0.0007834332 236 -0.1549607071 450 0.0726774642 23 -0.0007779869 237 -0.1640958855 451 0.0736406005 24 -0.0007803664 238 -0.1733808172 452 0.0744664394 25 -0.0007801449 239 -0.1828172548 453 0.0751576255 26 -0.0007757977 240 -0.1923966745 454 0.0757305756 27 -0.0007630793 241 -0.2021250176 455 0.0761748321 28 -0.0007530001 242 -0.2119735853 456 0.0765050718 29 -0.0007319357 243 -0.2219652696 457 0.0767204924 thirty -0.0007215391 244 -0.2320690870 458 0.0768230011 31 -0.0006917937 245 -0.2423016884 459 0.0768173975 32 -0.0006650415 246 -0.2526480309 460 0.0767093490 33 -0.0006341594 247 -0.2631053299 461 0.0764992170 34 -0.0005946118 248 -0.2736634040 462 0.0761992479 35 -0.0005564576 249 -0.2843214189 463 0.0758008358 36 -0.0005145572 250 -0.2950716717 464 0.0753137336 37 -0.0004606325 251 -0.3059098575 465 0.0747452558 38 -0.0004095121 252 -0.3168278913 466 0.0741003642 39 -0.0003501175 253 -0.3278113727 467 0.0733620255 40 -0.0002896981 254 -0.3388722693 468 0.0725682583 41 -0.0002098337 255 -0.3499914122 469 0.0717002673 42 -0.0001446380 256 0.3611589903 470 0.0707628710 43 -0.0000617334 257 0.3723795546 471 0.0697630244 44 0.0000134949 258 0.3836350013 472 0.0687043828 45 0.0001094383 259 0.3949211761 473 0.0676075985 46 0.0002043017 260 0.4062317676 474 0.0664367512 47 0.0002949531 261 0.4175696896 475 0.0652247106 48 0.0004026540 262 0.4289119920 476 0.0639715898 49 0.0005107388 263 0.4402553754 477 0.0626857808 - 34 040874 50 0.0006239376 264 0.4515996535 478 0.0613455171 51 0.0007458025 265 0.4629308085 479 0.0599837480 52 0.0008608443 266 0.4742453214 480 0.0585915683 53 0.0009885988 267 0.4855253091 481 0.0571616450 54 0.0011250155 268 0.4967708254 482 0.0557173648 55 0.0012577884 269 0.5079817500 483 0.0542452768 56 0.0013902494 270 0.5191234970 484 0.0527630746 57 0.0015443219 271 0.5302240895 485 0.0512556155 58 0.0016868083 272 0.5412553448 486 0.0497385755 59 0.0018348265 273 0.5522051258 487 0.0482165720 60 0.0019841140 274 0.5630789140 488 0.0466843027 61 0.0021461583 275 0.5738524131 489 0.0451488405 62 0.0023017254 276 0.5845403235 490 0.0436097542 63 0.0024625616 277 0.5951123086 491 0.0420649094 64 0.0026201758 278 0.6055783538 492 0.0405349170 65 0.0027870464 279 0.6159109932 493 0.0390053679 66 0.0029469447 280 0.6261242695 494 0.0374812850 67 0.0031125420 281 0.6361980107 495 0.0359697560 68 0.0032739613 282 0.6461269695 496 0.0344620948 69 0.0034418874 283 0.6559016302 497 0.0329754081 70 0.0036008268 284 0.6655139880 498 0.0315017608 71 0.0037603922 285 0.6749663190 499 0.0300502657 72 0.0039207432 286 0.6842353293 500 0.0286072173 73 0.0040819753 287 0.6933282376 501 0.0271859429 74 0.0042264269 288 0.7022388719 502 0.0257875847 75 0.0043730719 289 0.7109410426 503 0.0244160992 76 0.0045209852 290 0.7194462634 504 0.0230680169 77 0.0046606460 291 0.7277448900 505 0.0217467550 78 0.0047932560 292 0.7358211758 506 0.0204531793 79 0.0049137603 293 0.7436827863 507 0.0191872431 80 0.0050393022 294 0.7513137456 508 0.0179433381 81 0.0051407353 295 0.7587080760 509 0.0167324712 82 0.0052461166 296 0.7658674865 510 0.0155405553 83 0.0053471681 297 0.7727780881 511 0.0143904666 - 35 040874 84 0.0054196775 298 0.7794287519 512 -0.0132718220 85 0.0054876040 299 0.7858353120 513 -0.0121849995 86 0.0055475714 300 0.7919735841 514 -0.0111315548 87 0.0055938023 301 0.7978466413 515 -0.0101150215 88 0.0056220643 302 0.8034485751 516 -0.0091325329 89 0.0056455196 303 0.8087695004 517 -0.0081798233 90 0.0056389199 304 0.8138191270 518 -0.0072615816 91 0.0056266114 305 0.8185776004 519 -0.0063792293 92 0.0055917128 306 0.8230419890 520 -0.0055337211 93 0.0055404363 307 0.8272275347 521 -0.0047222596 94 0.0054753783 308 0.8311038457 522 -0.0039401124 95 0.0053838975 309 0.8346937361 523 -0.0031933778 96 0.0052715758 310 0.8379717337 524 -0.0024826723 97 0.0051382275 311 0.8409541392 525 -0.0018039472 98 0.0049839687 312 0.8436238281 526 -0.0011568135 99 0.0048109469 313 0.8459818469 527 -0.0005464280 100 0.0046039530 314 0.8480315777 528 0.0000276045 101 0.0043801861 315 0.8497805198 529 0.0005832264 102 0.0041251642 316 0.8511971524 530 0.0010902329 103 0.0038456408 317 0.8523047035 531 0.0015784682 104 0.0035401246 318 0.8531020949 532 0.0020274176 105 0.0032091885 319 0.8535720573 533 0.0024508540 106 0.0028446757 320 0.8537385600 534 0.0028446757 107 0.0024508540 321 0.8535720573 535 0.0032091885 108 0.0020274176 322 0.8531020949 536 0.0035401246 109 0.0015784682 323 0.8523047035 537 0.0038456408 110 0.0010902329 324 0.8511971524 538 0.0041251642 111 0.0005832264 325 0.8497805198 539 0.0043801861 112 0.0000276045 326 0.8480315777 540 0.0046039530 113 -0.0005464280 327 0.8459818469 541 0.0048109469 114 -0.0011568135 328 0.8436238281 542 0.0049839687 115 -0.0018039472 329 0.8409541392 543 0.0051382275 116 -0.0024826723 330 0.8379717337 544 0.0052715758 117 -0.0031933778 331 0.8346937361 545 0.0053838975 - 36 040874 118 -0.0039401124 332 0.8311038457 546 0.0054753783 119 -0.0047222596 333 0.8272275347 547 0.0055404363 120 -0.0055337211 334 0.8230419890 548 0.0055917128 121 -0.0063792293 335 0.8185776004 549 0.0056266114 122 -0.0072615816 336 0.8138191270 550 0.0056389199 123 -0.0081798233 337 0.8087695004 551 0.0056455196 124 -0.0091325329 338 0.8034485751 552 0.0056220643 125 -0.0101150215 339 0.7978466413 553 0.0055938023 126 -0.0111315548 340 0.7919735841 554 0.0055475714 127 -0.0121849995 341 0.7858353120 555 0.0054876040 128 0.0132718220 342 0.7794287519 556 0.0054196775 129 0.0143904666 343 0.7727780881 557 0.0053471681 130 0.0155405553 344 0.7658674865 558 0.0052461166 131 0.0167324712 345 0.7587080760 559 0.0051407353 132 0.0179433381 346 0.7513137456 560 0.0050393022 133 0.0191872431 347 0.7436827863 561 0.0049137603 134 0.0204531793 348 0.7358211758 562 0.0047932560 135 0.0217467550 349 0.7277448900 563 0.0046606460 136 0.0230680169 350 0.7194462634 564 0.0045209852 137 0.0244160992 351 0.7109410426 565 0.0043730719 138 0.0257875847 352 0.7022388719 566 0.0042264269 139 0.0271859429 353 0.6933282376 567 0.0040819753 140 0.0286072173 354 0.6842353293 568 0.0039207432 141 0.0300502657 355 0.6749663190 569 0.0037603922 142 0.0315017608 356 0.6655139880 570 0.0036008268 143 0.0329754081 357 0.6559016302 571 0.0034418874 144 0.0344620948 358 0.6461269695 572 0.0032739613 145 0.0359697560 359 0.6361980107 573 0.0031125420 146 0.0374812850 360 0.6261242695 574 0.0029469447 147 0.0390053679 361 0.6159109932 575 0.0027870464 148 0.0405349170 362 0.6055783538 576 0.0026201758 149 0.0420649094 363 0.5951123086 577 0.0024625616 150 0.0436097542 364 0.5845403235 578 0.0023017254 151 0.0451488405 365 0.5738524131 579 0.0021461583 - 37 040874 152 0.0466843027 366 0.5630789140 580 0.0019841140 153 0.0482165720 367 0.5522051258 581 0.0018348265 154 0.0497385755 368 0.5412553448 582 0.0016868083 155 0.0512556155 369 0.5302240895 583 0.0015443219 156 0.0527630746 370 0.5191234970 584 0.0013902494 157 0.0542452768 371 0.5079817500 585 0.0012577884 158 0.0557173648 372 0.4967708254 586 0.0011250155 159 0.0571616450 373 0.4855253091 587 0.0009885988 160 0.0585915683 374 0.4742453214 588 0.0008608443 161 0.0599837480 375 0.4629308085 589 0.0007458025 162 0.0613455171 376 0.4515996535 590 0.0006239376 163 0.0626857808 377 0.4402553754 591 0.0005107388 164 0.0639715898 378 0.4289119920 592 0.0004026540 165 0.0652247106 379 0.4175696896 593 0.0002949531 166 0.0664367512 380 0.4062317676 594 0.0002043017 167 0.0676075985 381 0.3949211761 595 0.0001094383 168 0.0687043828 382 0.3836350013 596 0.0000134949 169 0.0697630244 383 0.3723795546 597 -0.0000617334 170 0.0707628710 384 -0.3611589903 598 -0.0001446380 171 0.0717002673 385 -0.3499914122 599 -0.0002098337 172 0.0725682583 386 -0.3388722693 600 -0.0002896981 173 0.0733620255 387 -0.3278113727 601 -0.0003501175 174 0.0741003642 388 -0.3168278913 602 -0.0004095121 175 0.0747452558 389 -0.3059098575 603 -0.0004606325 176 0.0753137336 390 -0.2950716717 604 -0.0005145572 177 0.0758008358 391 -0.2843214189 605 -0.0005564576 178 0.0761992479 392 -0.2736634040 606 -0.0005946118 179 0.0764992170 393 -0.2631053299 607 -0.0006341594 180 0.0767093490 394 -0.2526480309 608 -0.0006650415 181 0.0768173975 395 -0.2423016884 609 -0.0006917937 182 0.0768230011 396 -0.2320690870 610 -0.0007215391 183 0.0767204924 397 -0.2219652696 611 -0.0007319357 184 0.0765050718 398 -0.2119735853 612 -0.0007530001 185 0.0761748321 399 -0.2021250176 613 -0.0007630793 -