JP4389333B2 - Data transmission apparatus and data transmission method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data transmission apparatus and a data transmission method for transmitting 1-bit digital audio data.
[0002]
[Prior art]
For example, digital audio data represented by PCM data is digitized with a predetermined sampling frequency and a predetermined number of quantization bits. Typical sampling frequencies are 32 KHz, 44.1 KHz, 48 KHz, and the like. Further, examples in which the number of quantization bits is 16 bits, 20 bits, 24 bits, and the like are known.
[0003]
[Problems to be solved by the invention]
In PCM data, the number of quantization bits is usually 16 bits. This means that 16 bits are regarded as one word, but transmitted from one device (or circuit unit) to another device (or circuit unit). This means that 16-bit unit transmission must be maintained. For example, even if only 15 bits are transmitted, data cannot be processed as one word at the transmission destination. For example, it cannot be decoded correctly.
Therefore, at the time of transmission, the transmission frequency is selected so that data transmission is performed in units of 16 bits, or an integer multiple thereof, and an appropriate state is ensured for word delimiters. Of course, the data sampling frequency also affects the selection of the transmission frequency. That is, the relationship between the sampling frequency and the number of quantization bits must be maintained.
In other words, the average transmission frequency during data transmission depends on the data sampling frequency and the number of quantization bits, and the degree of freedom in selecting the transmission frequency is very narrow.
In this specification, “average transmission frequency” is used to mean a transmission frequency in consideration of, for example, bursty transmission.
[0004]
The influence of the fixed average transmission frequency appears in, for example, transmission for broadcasting digital data or transmission for recording on a recording medium.
That is, in the transmission of data to be recorded or provided, flexible data transmission such as transmission at an arbitrary data amount / bit rate according to the recording medium or the situation on the receiving device side cannot be performed.
[0005]
[Means for Solving the Problems]
In view of such a situation, the present invention provides a technique that enables flexible data transmission.
[0006]
Therefore, in the present invention, the data transmission apparatus is configured to transmit and output 1-bit digital audio data at an arbitrary average transmission frequency, and to add information indicating the average transmission frequency to the data to be transmitted and output.
[0007]
More specifically, the data transmission apparatus according to the present invention is based on a transmission clock generation means capable of generating a transmission clock having an arbitrary frequency, and the frequency of the transmission clock generated by the transmission clock generation means based on a transmission frequency setting condition. shows a setting unit configured to set, the 1-bit digital audio data of a predetermined sampling frequency, as well as transmit power using the transmission clock generated by the transmission clock generator, the frequency of the transmission clock to the data to be transmitted output Te Transmission output means for adding information and performing transmission output.
The transmission output means performs data transmission to other devices connected by wire or wireless, and the setting means transmits the transmission path type or transmission capability of the transmission output means and the transmission. A transmission frequency setting condition according to the data size of 1-bit digital audio data to be transmitted and output from the output means is obtained, and a transmission frequency setting condition according to the reception capability of the other device is received, and these transmission frequency setting conditions are received. The frequency of the transmission clock is set based on
[0008]
Alternatively, the transmission output means transmits and outputs 1-bit digital audio data as data to be recorded on a recording medium, and the setting means transmits the transmission path type or transmission capability of the transmission output means and the transmission output. The transmission frequency setting condition according to the data size of the 1-bit digital audio data to be transmitted and output from the means is obtained, and the transmission frequency setting condition according to the type of the recording medium or the recordable capacity is received and transmitted. The frequency of the transmission clock is set based on the frequency setting condition.
[0009]
In the data transmission method of the present invention, 1-bit digital audio data is transmitted at an arbitrary average transmission frequency and added with information indicating the average transmission frequency.
The data transmission method of the present invention includes a setting procedure for setting a transmission clock frequency based on a transmission frequency setting condition, a transmission clock generating procedure for generating a transmission clock having a frequency set by the setting procedure, and the transmission clock. The transmission clock generated in the generation procedure is used to transmit and output 1-bit digital audio data having a predetermined sampling frequency, and information indicating the frequency of the transmission clock is added to the data to be transmitted and output. A transmission path for performing data transmission to another device connected by wire or wirelessly in the transmission output procedure, and transmitting and outputting in the transmission output procedure in the setting procedure. Type or transmission capability and data of 1-bit digital audio data to be transmitted and output With obtaining the transmission frequency setting condition according to the size, it receives the transmission frequency setting conditions corresponding receiving capability of the other device to set the frequency of the transmission clock on the basis of these transmission frequency setting conditions.
Data transmission method.
Alternatively, in the transmission output procedure, 1-bit digital audio data is transmitted and output as data to be recorded on the recording medium, and in the setting procedure, the type or transmission capability of the transmission path to be transmitted and output in the transmission output procedure and the transmission output are to be output. The transmission frequency setting condition according to the data size of the 1-bit digital audio data is obtained, the transmission frequency setting condition according to the type of the recording medium or the recordable capacity is received, and based on these transmission frequency setting conditions To set the transmission clock frequency.
[0010]
As a method for digitizing an audio signal, ΔΣ modulation is known, and 1-bit digital data obtained by the ΔΣ modulation is a data format used for conventional digital audio (for example, sampling frequency 44.1 KHz). Compared with data word length of 16 bits), it has a very high sampling frequency and a short data word length (for example, the sampling frequency is 64 times 44.1 KHz and the data word length is 1 bit), allowing wide transmission It features a frequency band. Also, even with a 1-bit signal by ΔΣ modulation, a high dynamic range can be ensured in an audio band that is low with respect to an oversampling frequency of 64 times. This feature can be applied to high-quality recorders and data transmission. Further, the ΔΣ-modulated signal can be returned to an analog audio signal by passing through a simple analog low-pass filter.
In such 1-bit digital audio data, for example, there is no definition of a 16-bit unit word or the like, and only 1-bit data is continuous. That is, the bit rate of data transmission is arbitrary, which does not regulate the average transmission frequency. Accordingly, the average transmission frequency can be freely selected for convenience during transmission.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a transmission apparatus 1 according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a transmission apparatus for transmitting 1-bit digital audio data to a receiving apparatus or a recording medium.
[0012]
As described above, 1-bit digital audio data is developed as data of higher quality than audio data in a normal CD (Compact Disc), and the sampling frequency is, for example, 16 times that of 44.1 KHz in the CD system. It is 1-bit data that is ΔΣ modulated as 2.842 MHz which is a very high sampling frequency. The frequency band is a wide range of DC component to 100 KHz, and the dynamic range is a data format that can realize 120 (dB) in the entire audio band.
[0013]
As illustrated, the transmission apparatus 1 includes an interface 11, a variable transmission clock generation unit 12, and a control unit 13.
The interface 11 is a part that sends input 1-bit digital audio data DT having a sampling frequency = 64 fs (for example, fs = 44.1 KHz) to the transmission path 2.
[0014]
The variable transmission clock generator 12 generates a transmission clock TCK used for transmission processing in the interface 11. It is assumed that the frequency of the transmission clock TCK can be variably generated.
[0015]
Although a specific example will be described later, the control unit 13 is a part that selects the frequency of the transmission clock TCK based on various transmission frequency setting conditions Sc.
That is, the average transmission frequency is selected based on the transmission frequency setting condition Sc, and the clock control signal Vck is supplied to the variable transmission clock generator 12. The variable transmission clock generator 12 generates a transmission clock TCK at a frequency indicated by the clock control signal Vck.
Further, the control unit 13 supplies a value Sdck indicating the selected transmission frequency to the interface 11.
[0016]
The 1-bit digital audio data DT input to the interface 11 is generated by the ΔΣ modulator 3 as shown in FIG.
The ΔΣ modulator 3 performs 1Δ modulation on the supplied audio signal to generate 1-bit digital audio data DT.
[0017]
In the ΔΣ modulator 3 of FIG. 2, the input terminal 21 indicates an input end of the audio signal S. A signal input from the input terminal 21 is supplied to the integrator 23 via the adder 22. The signal from the integrator 23 is supplied to the comparator 24, compared with the midpoint potential of the input signal from the input terminal 21, and subjected to 1-bit quantization processing for each sample period. Output as bit digital audio data.
The 1-bit digital audio data, which is the quantized data, is also supplied to the one-sample delay unit 25 and delayed by one sample period. This delay data is converted into an analog signal by a 1-bit D / A converter 26, supplied to an adder 22, and added to the input signal from the input terminal 21.
[0018]
In this way, the 1-bit digital audio data DT output from the ΔΣ modulator 3 is input to the interface 11 of FIG.
The interface 11 performs a process of sending 1-bit digital audio data DT to the transmission path 2 at a transmission frequency and bit rate based on the transmission clock TCK. The data to be sent (transmission data tDT) is 1-bit digital audio data. The transmission frequency value Sdck supplied from the control unit 13 is added to the stream as DT.
For example, transmission data tDT as shown in FIG. 3 is transmitted.
The example of FIG. 3 schematically shows an example in which 1-bit digital audio data DT is transmitted after adding a transmission frequency value Sdck with a predetermined number of bits to the head of a stream (or packet) as transmission data tDT. Is.
[0019]
Such transmission data tDT is sent to the transmission path 2.
The transmission path 2 may be a transmission path that connects devices such as an IEEE 1394 cable or a USB (Universal Serial Bus) cable, or an internal bus that connects circuit systems in a certain device. It may be a transmission line. Furthermore, it may be a transmission line such as a public line such as ISDN or a dedicated line. In addition, wireless transmission such as satellite communication, wireless telephone communication, and infrared communication is included in the category of the transmission path 2 here.
Accordingly, there are various possible transmission destinations of the 1-bit digital audio data DT. For example, as shown in FIG. 1, transmission to a certain receiving apparatus for output, transmission for recording on a recording medium, and the like are possible.
[0020]
Here, in the transmission data tDT of FIG. 3, the data size as the 1-bit digital audio data DT can be arbitrarily set, that is, can be determined according to the data to be transmitted and the convenience of the receiving side or the recording medium side.
This is because 1-bit digital audio data DT does not have a concept such as a word unit of 16-bit quantized PCM data, and the amount of data to be transmitted may be any number of bits.
For example, in the case of 16-bit quantized data, proper data processing cannot be performed on the receiving side unless a data amount that is an integral multiple of 16 bits is transmitted. However, in the case of 1-bit digital audio data DT, 1-bit or more Regardless of how many bits are transmitted, the receiver can handle them properly. Specifically, an audio signal can be extracted by filtering.
[0021]
For this reason, the data amount of the 1-bit digital audio data DT to be transmitted can be set arbitrarily.
Therefore, the value of the average transmission frequency (bit rate) can be arbitrarily set. If the bit rate is arbitrary, the average transmission frequency in actual transmission is determined by the convenience of the transmission. It can be thought that it is okay.
[0022]
Therefore, in this example, the control unit 13 sets the frequency of the transmission clock TCK so that data transmission is performed at an arbitrary transmission frequency, and some transmission frequency setting condition Sc is selected in order to select the transmission frequency. Is input to the control unit 13.
[0023]
4 and 5 show transmission frequency setting models, respectively.
FIG. 4 shows a case where the audio signal S is transmitted through the transmission path 2 in order to record it on the recording medium (media) 6.
The audio signal S is converted into 1-bit digital audio data DT by the ΔΣ modulator 3 shown in FIG. 2, and is sent to the transmission line 2 as, for example, transmission data tDT in the form of FIG. 3 by the transmission device 1 shown in FIG. .
The transmission data tDT is supplied to the recording signal processing unit 41 and processing for recording on the medium 6 is performed.
For example, the recording signal processing unit 41 first performs data capture processing on the transmission data tDTs supplied from the transmission path 2 at a processing frequency based on the transmission frequency value Sdck, and data as 1-bit digital audio data DT. Get the stream. The 1-bit digital audio data DT is subjected to error correction code addition and various encoding processes according to the recording format and modulation method of the recording medium 6 to generate a recording drive signal.
The recording drive signal is supplied to the recording head 42, and data writing to the medium 6 is performed by the recording head 42.
For example, when the medium 6 is an optical disk, a magneto-optical disk, a magnetic disk, a magnetic tape, or the like, recording is executed by driving an optical head or a magnetic head according to a recording drive signal.
Further, if the medium 6 is in the form of a memory card such as a flash memory, the interface 42 performs write access to the medium 6.
[0024]
Here, the setting of the transmission frequency by the transmission apparatus 1 is performed under the following conditions, for example.
First, the recording control unit 43 executing the control on the recording device unit side, the recordable capacity (remaining amount) of the loaded medium 6, the recordable position on the medium, and the type of the medium 6 Therefore, it is conceivable to transmit the capacity information and type information of these media 6 to the transmission apparatus 1 as the transmission frequency setting condition Sc1.
If the transmission apparatus 1 side and the recording control unit 43 side are in an integrated apparatus, this transmission can be performed by an internal bus of the apparatus or other communication system. Further, if it is a separate device, the transmission path 2 may be used.
[0025]
Further, since the transmission device 1 can naturally understand the type and transmission method of the connected transmission path 2, information on the transmission capability of the transmission path 2, such as transmission band and transmission speed, can be obtained as the transmission frequency setting condition Sc2. . Specifically, the interface 11 can transmit a transmission frequency setting condition Sc2 as information regarding the transmission path 2 to the control unit 13.
[0026]
Further, on the transmission apparatus 1 side, the amount of data can be discriminated due to the fact that the audio signal S (1-bit digital audio data DT) to be recorded is recorded on some medium or buffered, etc. When the amount of data to be transmitted can be arbitrarily set, information on the amount of data to be transmitted can be obtained as the transmission frequency setting condition Sc3.
[0027]
FIG. 5 shows a case where the audio signal S is transmitted through the transmission path 2 in order to transmit it to the receiving apparatus side for the purpose of broadcasting, distribution, and the like.
As in FIG. 4, the audio signal S is converted into 1-bit digital audio data DT by the ΔΣ modulator 3, and transmitted to the transmission path 2 as transmission data tDT by the transmission device 1.
The transmission data tDT is received by the receiving device 51, and a required process is performed by the reception data processing unit 52.
For example, the receiving device 51 first performs data capture processing on the transmission data tDTs supplied from the transmission path 2 at a processing frequency based on the transmission frequency value Sdck, and generates a data stream as 1-bit digital audio data DT. obtain. For the 1-bit digital audio data DT, the reception data processing unit 52 performs a filtering process for reproduction output, for example, to obtain an analog audio signal, and amplifies and outputs the analog audio signal. In the case of data distribution or the like, for example, it is conceivable to perform processing for executing recording on a predetermined recording medium.
[0028]
In this case, the reception device 51 may transmit information such as the reception capability, for example, the value of the processing clock for data capture and the buffering capability, to the transmission device 1 as the transmission frequency setting condition Sc4. Conceivable.
This transmission may be performed using the transmission path 2 or other transmission paths. Alternatively, if the reception capability of the reception device 51 is known in advance on the transmission device 1 side, the value of the transmission frequency setting condition Sc4 may be held on the transmission device 1 side. For example, the user of the transmission device 1 may input information on the reception device 51.
The transmission apparatus 1 can obtain the transmission frequency setting condition Sc2 as information on the transmission path 2 and can obtain information on the amount of data to be transmitted as the transmission frequency setting condition Sc3 as in the case of FIG. It is the same.
[0029]
For example, in the transmission model as shown in FIGS. 4 and 5, the control unit 13 of the transmission apparatus 1 sets the frequency of the transmission clock based on part or all of the transmission frequency setting conditions Sc1, Sc2, Sc3, and Sc4. You only have to set it.
As a result, it is possible to flexibly set the bit rate according to the transmission status and purpose and transmit.
[0030]
For example, when it is desired to record as much data as can be recorded according to the recordable capacity (remaining amount) of the medium 6, the remaining data amount is 1-bit digital audio data DT and the transmission data size is arbitrary. In this case, transmission can be performed at an average transmission frequency suitable for the amount of data.
[0031]
Further, when the processing clock at the time of data acquisition is limited on the receiving device side, transmission at an average transmission frequency according to the receiving capability on the receiving device side is possible.
Of course, the average transmission frequency can be set according to the amount of data to be transmitted and the capacity of the transmission path 2. This means that it is possible to easily cope with a case where the transmission path 2 is changed.
[0032]
That is, according to this example, in transmission of 1-bit digital audio data DT, transmission at a suitable average transmission frequency can be executed arbitrarily arbitrarily according to various situations such as a transmission side, a reception side, a medium, or a transmission path. In addition, since the transmission frequency value Sdck is added to the transmission data tDT, the transmission data tDT transmitted at an arbitrary average transmission frequency can be appropriately captured at the transmission destination. .
[0033]
In addition, this example can be applied to transmission to media that cannot cope with a sampling frequency different from the sampling frequency of PCM data or a delimiter by the number of quantization bits such as 16 bits, 20 bits, and 24 bits.
Further, for example, although the capacity allocated to audio data is not instantaneously constant, a constant bit rate is ensured over a certain period, and the present invention can be applied to a system in which the number of bits allocated every time is variable.
[0034]
Although the embodiments have been described above, the present invention can be applied to a wide variety of apparatuses and fields, and various examples of the configuration of the transmission apparatus can be considered.
[0035]
【The invention's effect】
As can be seen from the above description, according to the present invention, in transmission of 1-bit digital audio data, a suitable average transmission is arbitrarily arbitrarily selected according to various situations such as a transmission side, a reception side, a medium, or a transmission path. Transmission by frequency can be executed. Further, since the value indicating the transmission frequency is added to the data to be transmitted, the transmitted data can be properly captured at the transmission destination even if the transmission is performed at an arbitrary average transmission frequency. For these reasons, the present invention has an effect of enabling flexible data transmission as an appropriate transmission frequency according to various situations.
[Brief description of the drawings]
FIG. 1 is a block diagram of a transmission apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a ΔΣ modulator according to an embodiment.
FIG. 3 is an explanatory diagram of transmission data according to the embodiment.
FIG. 4 is a block diagram of a transmission model according to the embodiment.
FIG. 5 is a block diagram of a transmission model of the embodiment.
[Explanation of symbols]
1 transmission device, 2 transmission path, 3 ΔΣ modulator, 6 media, 11 interface, 12 variable transmission clock generation unit, 13 control unit, 41 recording signal processing unit, 43 recording control unit, 51 receiving device

Claims (4)

A transmission clock generation means capable of generating a transmission clock of an arbitrary frequency;
Setting means for setting the frequency of the transmission clock generated by the transmission clock generating means based on transmission frequency setting conditions ;
1-bit digital audio data having a predetermined sampling frequency is transmitted and output using the transmission clock generated by the transmission clock generating means, and information indicating the frequency of the transmission clock is added to the data to be transmitted and transmitted. Transmission output means for performing,
Equipped with a,
The transmission output means performs data transmission to other devices connected by wire or wirelessly,
The setting means obtains a transmission frequency setting condition according to the type or transmission capability of the transmission path transmitted by the transmission output means and the data size of 1-bit digital audio data to be transmitted from the transmission output means, A data transmission device that receives transmission frequency setting conditions according to the reception capability of the other device and sets the frequency of the transmission clock based on these transmission frequency setting conditions . A transmission clock generation means capable of generating a transmission clock of an arbitrary frequency;
Setting means for setting the frequency of the transmission clock generated by the transmission clock generating means based on transmission frequency setting conditions;
1-bit digital audio data having a predetermined sampling frequency is transmitted and output using the transmission clock generated by the transmission clock generating means, and information indicating the frequency of the transmission clock is added to the data to be transmitted and transmitted. Transmission output means for performing,
With
The transmission output means transmits and outputs 1-bit digital audio data as data to be recorded on the recording medium,
The setting means obtains a transmission frequency setting condition according to the type or transmission capability of the transmission path transmitted by the transmission output means and the data size of 1-bit digital audio data to be transmitted from the transmission output means, A data transmission apparatus that receives transmission frequency setting conditions according to the type of the recording medium or the recordable capacity situation and sets the frequency of the transmission clock based on the transmission frequency setting conditions . A setting procedure for setting the frequency of the transmission clock based on the transmission frequency setting condition ;
A transmission clock generation procedure for generating a transmission clock of the frequency set in the above setting procedure;
Using the transmission clock generated in the transmission clock generation procedure, 1-bit digital audio data having a predetermined sampling frequency is transmitted and output, and information indicating the frequency of the transmission clock is added to the data to be transmitted and the transmission output is generated. The transmission output procedure to be performed, and
Is done ,
In the above transmission output procedure, while performing data transmission to other devices connected by wire or wirelessly,
In the setting procedure, a transmission frequency setting condition corresponding to the type or transmission capability of the transmission line to be transmitted and output in the transmission and output procedure and the data size of the 1-bit digital audio data to be transmitted and output is obtained. A data transmission method for receiving transmission frequency setting conditions according to reception capability and setting the frequency of a transmission clock based on these transmission frequency setting conditions . A setting procedure for setting the frequency of the transmission clock based on the transmission frequency setting condition;
A transmission clock generation procedure for generating a transmission clock having a frequency set in the above setting procedure;
The transmission clock generated in the transmission clock generation procedure is used to transmit and output 1-bit digital audio data having a predetermined sampling frequency, and information indicating the frequency of the transmission clock is added to the data to be transmitted and output. The transmission output procedure to be performed, and
Is done,
In the transmission output procedure, 1-bit digital audio data is transmitted and output as data to be recorded on the recording medium.
In the setting procedure, a transmission frequency setting condition corresponding to the type or transmission capability of the transmission line to be transmitted and output in the transmission and output procedure and the data size of the 1-bit digital audio data to be transmitted and output is obtained, and the type of the recording medium Alternatively, the transmission frequency setting conditions corresponding to the recordable capacity situation are received, and the transmission clock frequency is set based on these transmission frequency setting conditions.
Data transmission method.

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