JP3750705B2 - Speech coding transmission method and speech coding transmission apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a voice encoding transmission method and a voice encoding transmission apparatus for efficiently transmitting a voice signal using a transmission line.
[0002]
[Prior art]
A conventional speech encoding method and apparatus will be described. FIG. 5 is a block diagram showing a basic configuration of a conventional speech coding apparatus. As shown in the figure, the speech coding apparatus includes a frequency envelope calculation means 1, a masking threshold value determination means 2A, an adaptive bit allocation means 3, and first to Nth band divisions for dividing a band into first to Nth bands. Means 4 includes first to Nth quantization means 5 for performing quantization for each band, first to Nth entropy encoding means 6 for performing entropy encoding for each band, and a multiplexer 7. The
[0003]
First, the speech envelope input to the frequency envelope calculation means 1 is required to have a spectral envelope in units of frames. Based on the obtained spectral envelope, the masking threshold value determining means 2A determines the masking threshold value of the band that is divided. This masking threshold is determined by the simultaneous masking effect considering the critical bandwidth. The adaptive bit allocation means 3 obtains a spectrum envelope component for each band for an input signal exceeding the obtained masking threshold. The bit allocation amount for each band is determined according to the ratio.
[0004]
On the other hand, when the input signal is input to the first to Nth band dividing means 4, it is divided into the first to Nth N bands. The output signals of the first to Nth band dividing means 4 are respectively input to the first to Nth quantizing means 5 and quantized with the number of bits given by the adaptive bit allocation means 3. Each quantized band division signal is input to the first to Nth entropy encoding means 6 and subjected to entropy encoding for eliminating redundancy. The encoded data of each band is collected by the multiplexer 7 together with the bit allocation information determined by the adaptive bit allocation means 3 and sent to the transmission line.
[0005]
[Problems to be solved by the invention]
However, in the above method, the encoded data is reduced by using the simultaneous masking effect in order to improve the encoding efficiency. However, the influence of the ambient noise on the listener side receiving the audio signal and the listener It does not take into account individual hearing ability (auditory characteristics). Especially for listeners who have a high noise level or who cannot listen to the entire audible band in the receiving-side environment, receiving such a band division signal unilaterally acquires redundant information. .
[0006]
The present invention has been made in view of the above-described problems of the prior art, and is based on the noise characteristics around the listener receiving the audio signal and the hearing characteristics of the listener. It is an object of the present invention to realize a speech encoding / transmission method and speech encoding / transmission apparatus that improve signal reproduction quality or encoding efficiency.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 of the present application is a speech encoding transmission method applied on the transmission side in order to compensate reproduction quality on hearing based on listening conditions on the reception side, Request the transfer of information about the ambient noise characteristics of the receiving side from the receiving side to obtain the ambient noise spectrum information from the receiving side, and request the transfer of information about the hearing characteristics of the receiving listener from the transmitting side to the receiving side. Obtaining the listener's hearing characteristic information from the receiving side , obtaining the spectral envelope of the audio signal to be encoded and transmitted, the masking threshold for the spectral envelope by the simultaneous masking effect, the ambient noise spectral information obtained from the receiving side and the receiving side at least one corrected based on the basis of the new masking threshold obtained reduced the allocation of bit allocation amount for each frequency band of the listener hearing characteristic information obtained from To make it adjusts performs encoding at a predetermined coding algorithm based on the adjusted bit allocation amount for each frequency band signal, which is characterized in that transmission to the receiver, the claims hereof The invention described in claim 5 is a speech coding and transmission apparatus applied on the transmission side in order to compensate for the audible reproduction quality based on listening conditions on the reception side, and obtains ambient noise spectrum information on the reception side on the transmission side and noise characteristic reference means for a hearing characteristic reference means to obtain the listener hearing characteristic information of the receiving side on the transmitting side, the frequency envelope calculating means for calculating a spectrum envelope of the speech signal to be transmitted coded, the by simultaneous masking effect Ma is corrected based on the masking threshold for the spectral envelope, to at least one listener hearing characteristic information obtained with ambient noise spectrum information obtained from the reception side from the reception side A king threshold value determining means, an adaptive bit allocating means for adjusting the allocation of the bit allocation amount for each frequency band based on the obtained new masking threshold value, and a signal for each frequency band signal based on the adjusted bit allocation amount. On the other hand, an encoding means for encoding with a predetermined encoding algorithm is provided.
[0008]
The invention according to claim 2 of the present application is a speech coding transmission method applied on the transmission side in order to compensate the audible reproduction quality based on the listening condition on the reception side, and is received from the transmission side to the reception side. Request the transfer of information on the ambient noise characteristics of the receiver to obtain ambient noise spectrum information from the receiver, and request the transfer of information on the hearing characteristics of the receiver of the receiver from the transmitter to the receiver to request the listener from the receiver Obtain hearing characteristic information , determine the spectral envelope of the audio signal to be encoded and transmitted, and obtain the masking threshold for the spectral envelope by the simultaneous masking effect, the ambient noise spectrum information obtained from the receiving side and the listener's hearing obtained from the receiving side corrected based on at least one particular feature information, the bit allocation amount for each frequency band based on a new masking threshold obtained, SN value is a predetermined value or more of the audio signals It was changed to a performs encoding at a predetermined coding algorithm for each frequency band signal based on the changed bit allocation amount, which is characterized in that transmission to the receiver, the present application claims The invention according to Item 6 is a speech coding and transmission apparatus applied on the transmission side in order to compensate the reproduction quality on hearing based on listening conditions on the reception side, and the ambient noise spectrum information on the reception side is transmitted on the transmission side. By means of the simultaneous masking effect, the noise characteristic reference means to be obtained, the hearing characteristic reference means to obtain the listener's hearing characteristic information on the receiving side, the frequency envelope calculation means to obtain the spectral envelope of the audio signal to be encoded and transmitted, and a masking threshold for the spectral envelope, at least one or more correction based the listener hearing characteristic information obtained with ambient noise spectrum information obtained from the reception side from the reception side Masking threshold value determining means, adaptive bit allocating means for changing the bit allocation amount for each frequency band based on the obtained new masking threshold value so that the SN value of the audio signal is equal to or greater than a predetermined value, and changed bit allocation And encoding means for encoding each frequency band signal with a predetermined encoding algorithm based on the quantity.
[0009]
According to the third and seventh aspects of the present invention, in the above-described speech coding transmission method and speech coding transmission device , the masking threshold is corrected based on the masking noise obtained from the ambient noise spectrum information when the masking threshold is corrected. It is characterized by adjusting.
[0010]
According to the fourth and eighth aspects of the present invention, in the voice encoding transmission method and the voice encoding transmission apparatus described above, the frequency band of the listener obtained based on the listener hearing characteristic information when the masking threshold is corrected. The masking threshold value is adjusted based on the minimum audible value and the critical bandwidth for each.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
Hereinafter, a speech coding and transmission method according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a basic configuration of a speech encoding apparatus according to the present embodiment. The same parts as those in the conventional example are given the same reference numerals, and the description thereof is omitted. This speech encoding apparatus includes a frequency envelope calculation means 1, a masking threshold value determination means 2B, an adaptive bit allocation means 3, first to Nth band division means 4 for dividing a band into N bands, and performs quantization for each band. In addition to first to Nth quantizing means 5 to perform, first to Nth entropy encoding means 6 to perform entropy coding for each band, multiplexer 7, noise characteristic reference means 8, hearing characteristic reference means 9 It is comprised including.
[0012]
The noise characteristic reference means 8 is means for obtaining the noise characteristic of the reception side input via the transmission path and giving it to the masking threshold value determination means 2B. The hearing characteristic reference means 9 is means for obtaining the hearing characteristic of the listener inputted via the transmission path and giving it to the masking threshold value determination means 2B. The masking threshold value determining means 2B is a means for determining a masking threshold value based on the frequency envelope information of the input audio signal and the noise characteristics and hearing characteristics on the receiving side.
[0013]
The operation of the speech encoding apparatus configured as described above will be described with reference to FIGS. 2 and 3 are flowcharts showing the signal processing flow of the speech coding and transmission method according to the present embodiment.
[0014]
In step S1, the transmitting side first requests the transfer of noise spectrum information related to the ambient noise characteristics on the receiving side in order to know the ambient noise environment on the receiving side. On the other hand, in step S11 of FIG. 3, the receiving side accepts a transfer request for information on ambient noise characteristics from the transmitting side. In the next step S12, the receiving side measures the noise spectrum related to the ambient noise on the receiving terminal side, and transfers the obtained noise spectrum information to the noise characteristic reference means 8 on the transmitting side. In this way, the transmitting side obtains ambient noise spectrum information.
[0015]
In step S2 of FIG. 2, the transmitting side requests transfer of hearing information relating to the hearing characteristics of the receiving listener in order to know the hearing characteristics of the receiving listener. On the other hand, in step S21 in FIG. 3, the receiving side accepts a request for transferring the hearing information of the listener on the receiving side from the transmitting side. In the next step S22, the hearing information of the listener on the receiving terminal side is collected, and the obtained hearing information is transferred to the hearing characteristic reference means 9 on the transmitting side. It is assumed that the accurate auditory characteristics of the listener on the receiving terminal side have already been obtained, and that information can be transferred from the receiving terminal. If information on the ambient noise characteristics on the receiving side and the hearing characteristics of the listener cannot be obtained, the transmitting side estimates the information.
[0016]
In the next step S3, the masking threshold value determination means 2B on the transmission side obtains the spectrum envelope of the input signal in units of frames, and adds the envelope of the ambient noise spectrum obtained from the reception side to this. In step S4, a masking threshold value due to the simultaneous masking effect is determined. Thereby, the masking threshold value including the ambient noise environment on the receiving side is obtained.
[0017]
In step S5, the masking threshold value determining unit 2B corrects the masking threshold value based on the minimum audible value that is the hearing characteristic of the listener obtained through the hearing characteristic reference unit 9. As a result, it is possible to eliminate transmission of useless encoded data outside the audible range, for example, when the listener has deteriorated sensitivity at high frequencies.
[0018]
In step S6, the adaptive bit allocation means 3 adaptively changes the bit allocation amount using the masking threshold obtained above and the spectrum envelope of the input signal. In the present embodiment, it is assumed that the upper limit of the bit rate of encoded audio to be transmitted is limited. Next, a ratio of components exceeding the masking threshold value of each band is obtained, and bit allocation is performed according to the ratio. Although the total number of bits is set to a predetermined value or less, the allocated amount is adaptively changed according to the previous bit allocation.
[0019]
The operation after bit allocation is the same as in the conventional example. That is, in step S7, the band dividing means 4 divides the input signal into bands. The quantization means 5 quantizes the number of bits assigned to each band, and the entropy coding means 6 performs entropy coding. In the next step S8, the multiplexer 7 multiplexes the encoded data of each band and the bit allocation number allocated for quantization, and outputs them to the transmission line.
[0020]
(Embodiment 2)
Next, a speech coding and transmission method according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 4 is a flowchart showing a signal processing flow of the speech coding and transmission method according to the present embodiment. Since the basic configuration of the speech encoding apparatus is the same as that in FIG. 1, citation of each unit in FIG. 1 is omitted.
[0021]
In step T1 in FIG. 4, first, the transmitting side requests transfer of noise spectrum information related to the ambient noise characteristics on the receiving side in order to know the ambient noise environment on the receiving side. On the other hand, in step T11 of FIG. 3, the receiving side accepts a transfer request for information on ambient noise characteristics from the transmitting side. In the next step T12, the receiving side measures the noise spectrum related to the ambient noise on the receiving terminal side, and transfers the obtained noise spectrum information to the transmitting side. In this way, the transmitting side obtains ambient noise spectrum information.
[0022]
In the next step T2, the transmitting side requests transfer of hearing information relating to the hearing characteristics of the listener in order to know the hearing characteristics of the listener on the receiving side. On the other hand, in step T21 of FIG. 3, the receiving side accepts a transfer request for information related to the hearing characteristics of the listener on the receiving side from the transmitting side. In the next step T22, the hearing information of the listener on the receiving terminal side is collected, and the obtained hearing information is transferred to the transmitting side. Note that it is assumed that accurate hearing characteristics of the listener on the receiving terminal side have already been obtained, and that information can be transferred from the receiving terminal.
[0023]
In the next step T3, the transmitting side obtains the spectrum envelope of the input signal in units of frames, and adds the envelope of the ambient noise spectrum obtained from the receiving side to this. In step T4, a masking threshold value due to the simultaneous masking effect is determined. Thereby, the masking threshold value including the ambient noise environment on the receiving side is obtained.
[0024]
In step T5, the masking threshold is corrected based on the minimum audible value that is the hearing characteristic of the listener on the receiving side. As a result, when the listener has deteriorated the sensitivity of the high frequency, for example, transmission of encoded data outside the audible range can be eliminated in advance.
[0025]
In step T6, the bit allocation amount is adaptively changed using the masking threshold obtained above and the spectrum envelope of the input signal. In the present embodiment, it is assumed that the bit rate of transmitted encoded audio can be varied. First, the number of bits is determined from the absolute value of the component exceeding the masking threshold of each band so that the SN value of the voice becomes a predetermined value. For this reason, the total number of bits is not a constant value, but is adaptively varied according to the signal state and the like.
[0026]
The operation after bit allocation is the same as in the conventional example. That is, in step T7, the input signal is divided into bands, quantized with the number of bits assigned to each band, and entropy coding is performed. In the next step T8, the encoded data of each band and the number of bits allocated for quantization are multiplexed and output to the transmission line.
[0027]
【The invention's effect】
As described above, according to the first to eighth aspects of the present invention, by limiting the number of bits of encoded data in the entire band in consideration of the influence of ambient noise on the reception side and the hearing characteristics of the listener on the reception side. Thus, it is possible to reduce the amount of information to be encoded and transmitted.
[0028]
According to the inventions of claims 2, 3, 4, 6, 7, and 8, by changing the bit distribution to each band in consideration of the influence of ambient noise on the receiving side and the hearing characteristics of the listener, There is an effect that the encoded reproduction quality on hearing can be improved.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a speech coding apparatus for realizing a speech coding and transmission method of the present invention.
FIG. 2 is a flowchart (part 1) showing signal processing of the speech coding and transmission method according to Embodiment 1 of the present invention.
FIG. 3 is a flowchart (part 2) illustrating signal processing of the speech coding and transmission method according to the first and second embodiments.
FIG. 4 is a flowchart (part 1) showing signal processing of the speech coding and transmission method according to Embodiment 2 of the present invention.
FIG. 5 is a configuration diagram of a conventional speech encoding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Frequency envelope calculation means 2A, 2B Masking threshold value determination means 3 Adaptive bit allocation means 4 Band division means 5 Quantization means 6 Entropy encoding means 7 Multiplexer 8 Noise characteristic reference means 9 Hearing characteristic reference means

Claims (8)

A speech coding and transmission method applied on the transmitting side to compensate for auditory reproduction quality based on listening conditions on the receiving side,
Obtain the ambient noise spectrum information from the receiver by requesting the transfer of information on the ambient noise characteristics of the receiver from the transmitter to the receiver .
Request the transfer of information about the hearing characteristics of the receiving listener from the transmitting side to the receiving side to obtain the listener's hearing characteristics information from the receiving side ,
Obtain the spectral envelope of the audio signal to be encoded and transmitted,
Correcting the masking threshold for the spectral envelope by a simultaneous masking effect based on at least one of ambient noise spectrum information obtained from the receiver and listener hearing characteristic information obtained from the receiver ;
Adjust to reduce the allocation of bit allocation for each frequency band based on the new masking threshold obtained,
A speech encoding transmission method, wherein each frequency band signal is encoded with a predetermined encoding algorithm based on the adjusted bit allocation amount and transmitted to a receiving side . A speech coding and transmission method applied on the transmitting side to compensate for auditory reproduction quality based on listening conditions on the receiving side,
Obtain the ambient noise spectrum information from the receiver by requesting the transfer of information on the ambient noise characteristics of the receiver from the transmitter to the receiver .
Request the transfer of information about the hearing characteristics of the receiving listener from the transmitting side to the receiving side to obtain the listener's hearing characteristics information from the receiving side ,
Obtain the spectral envelope of the audio signal to be encoded and transmitted,
Correcting the masking threshold for the spectral envelope by a simultaneous masking effect based on at least one of ambient noise spectrum information obtained from the receiver and listener hearing characteristic information obtained from the receiver ;
Based on the obtained new masking threshold, the bit allocation amount for each frequency band is changed so that the SN value of the audio signal is a predetermined value or more,
A speech coding and transmission method characterized in that each frequency band signal is coded with a predetermined coding algorithm based on the changed bit allocation amount and is transmitted to the receiving side . 3. The speech encoding and transmitting method according to claim 1, wherein the masking threshold is adjusted based on the masking noise obtained from the ambient noise spectrum information when the masking threshold is corrected. 3. The masking threshold is adjusted based on a minimum audible value and a critical bandwidth for each frequency band of the listener obtained based on the listener hearing characteristic information when correcting the masking threshold. The voice encoded transmission method described. A speech coding and transmission device applied on the transmission side to compensate for the audible reproduction quality based on the listening condition on the reception side,
Noise characteristic reference means for obtaining ambient noise spectrum information on the receiving side on the transmitting side ;
A hearing characteristic reference means for obtaining the listener's hearing characteristic information on the receiving side on the transmitting side ;
A frequency envelope calculating means for obtaining a spectral envelope of a voice signal to be encoded and transmitted;
A masking threshold value determining means for correcting a masking threshold value related to the spectrum envelope by a simultaneous masking effect based on at least one of ambient noise spectrum information obtained from the receiving side and listener hearing characteristic information obtained from the receiving side ;
Adaptive bit allocation means for adjusting the allocation of the bit allocation amount for each frequency band based on the obtained new masking threshold;
An audio encoding transmission apparatus comprising: encoding means for encoding each frequency band signal with a predetermined encoding algorithm based on the adjusted bit allocation amount. A speech coding and transmission device applied on the transmission side to compensate for the audible reproduction quality based on the listening condition on the reception side,
Noise characteristic reference means for obtaining ambient noise spectrum information on the receiving side on the transmitting side ;
A hearing characteristic reference means for obtaining the listener's hearing characteristic information on the receiving side on the transmitting side ;
A frequency envelope calculating means for obtaining a spectral envelope of a voice signal to be encoded and transmitted;
A masking threshold value determining means for correcting a masking threshold value related to the spectrum envelope by a simultaneous masking effect based on at least one of ambient noise spectrum information obtained from the receiving side and listener hearing characteristic information obtained from the receiving side ;
Adaptive bit allocation means for changing the bit allocation amount for each frequency band based on the obtained new masking threshold so that the SN value of the audio signal is equal to or greater than a predetermined value;
An audio encoding transmission apparatus comprising: encoding means for encoding each frequency band signal with a predetermined encoding algorithm based on the changed bit allocation amount. 7. The speech coding and transmitting apparatus according to claim 5, wherein the masking threshold is adjusted based on the masking noise obtained from the ambient noise spectrum information when the masking threshold is corrected. 7. The masking threshold value is adjusted based on a minimum audible value and a critical bandwidth for each frequency band of the listener obtained by the listener hearing characteristic information when correcting the masking threshold value. Voice encoding transmission device.

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