JP5948793B2 - Sound processing apparatus, sound processing method and program - Google Patents

Description

  The present invention relates to a sound processing apparatus, a sound processing method, and a program for processing echo-hided data.

  Conventionally, there is a technique called steganography in which predetermined data is embedded in an area that is difficult for humans to detect image data and audio data. The predetermined data is also referred to as additional data below.

Steganography can add new information only on existing channels,
Used for copyright protection and transmission of confidential data.

  For example, there is an echo hiding method as means for adding additional data to audio data. This method is a technique in which the original audio data is echoed with a delay time that cannot be detected by humans, and the delay time is sent as additional data.

  When the receiver that receives the audio data obtains the cepstrum of the audio data, a significant large value is obtained for the delay time quefrency with which the echo is applied, and a correspondence table between the delay time and the data determined as the transmission side in advance. Therefore, the additional data can be reproduced.

  The cepstrum is data obtained by logarithmically transforming a Fourier transform result and further applying a Fourier transform, and is used when obtaining the pitch of audio data. Each element of the cepstrum is called quefrency, and the dimension is the same as time.

  In the echo hiding method, since the interval for updating the additional data is known, the additional data can be extracted with high accuracy by combining the update timing with the readout timing of the audio data.

  For example, there is a technique for determining a segment boundary based on whether a distance between an estimated value of phase shift of a segment in which a watermark is embedded and an average value of the phase shift is equal to or greater than a predetermined threshold.

Special table 2009-515371

  Here, when the additional data is continuously added to the audio data by the echo hiding method, the deterioration of the sound quality is conspicuous if the audio data becomes discontinuous. Therefore, in practice, the echo is not suddenly switched at the update timing of the additional data, but the echo of the previous data is faded out and the echo of the next data is faded in so that the echo is gradually switched.

  In this case, when the read timing of the audio data deviates from the update timing of the additional data on the receiving device side, the cepstrum calculation of the audio data to which a different echo is added is performed, and the additional data is appropriately extracted. There was a problem that it was not possible.

  Therefore, the disclosed technique aims to provide a sound processing device, a sound processing method, and a program capable of improving the extraction accuracy of additional data with respect to the sound data subjected to echo hiding while suppressing the processing amount. To do.

In a sound processing apparatus according to an aspect of the disclosure, audio data having a length corresponding to the update interval is divided into a plurality of audio data to which predetermined data is added at each update interval based on an echo signal delayed for a predetermined time. Determining whether the number of consecutive frames having the same predetermined data extracted based on the result of cepstrum calculation of each frame is equal to or greater than a predetermined value. of a first determination unit that determines the predetermined data for the update interval, and an output unit for outputting a predetermined data said determined out of the frames, the plurality for a plurality of frames with the same predetermined data continuously is extracted a center calculation unit for determining the center time for the entire frame, by adding the update interval to the center time obtained, the predetermined number used for the extraction of the following additional data Based on the determined cepstrum calculation results for a predetermined number of frames and a first determination unit that determines frames, the most extracted predetermined data is determined, and the most extracted predetermined data is output to the output unit. A second determination unit.

  According to the disclosed technology, it is possible to improve the extraction accuracy of additional data for echo-hided audio data while suppressing the processing amount.

1 is a block diagram illustrating an example of a configuration of a sound processing device according to Embodiment 1. FIG. The figure which shows an example of an encoding frame. The figure which shows an example of a decoding frame. The figure which shows an example of a cepstrum calculation result. FIG. 3 is a block diagram illustrating an example of a function of a determination unit according to the first embodiment. FIG. 5 is a diagram for explaining additional data determination processing according to the first embodiment. 3 is a flowchart illustrating an example of processing performed by the sound processing apparatus according to the first embodiment. FIG. 9 is a block diagram illustrating an example of a function of a determination unit according to the second embodiment. FIG. 10 is a diagram for explaining additional data determination processing according to the second embodiment. 9 is a flowchart illustrating an example of processing of a sound processing device according to a second embodiment. FIG. 10 is a block diagram illustrating an example of a function of a determination unit according to the third embodiment. FIG. 10 is a diagram for explaining additional data determination processing according to the third embodiment. 9 is a flowchart illustrating an example of processing of a sound processing device according to a third embodiment. FIG. 10 is a block diagram illustrating an example of a configuration of a sound processing device according to a fourth embodiment. FIG. 10 is a diagram for explaining additional data determination processing according to the fourth embodiment. 10 is a flowchart illustrating an example of processing of a sound processing device according to a fourth embodiment. FIG. 10 is a block diagram illustrating an example of hardware of a mobile terminal device according to a fifth embodiment.

  Hereinafter, adding an echo having a predetermined delay time to audio data as predetermined data is referred to as encoding, and a series of audio data strings in which one additional data is embedded is referred to as an encoding frame. The predetermined data is also called additional data as described above. Further, extracting additional data from audio data on the sound processing device side that receives the sound is called decoding, and a series of audio data strings to be decoded is called a decoding frame.

[Example 1]
<Configuration>
FIG. 1 is a block diagram illustrating an example of the configuration of the sound processing device 1 according to the first embodiment. The sound processing device 1 illustrated in FIG. 1 includes a microphone unit 11, an audio data count unit 12, an audio data storage unit 13, a calculation unit 14, a decoding unit 15, a determination unit 16, and an output unit 17.

  The microphone unit 11 converts sound into audio data of an electrical signal, and outputs the converted audio data to the audio data count unit 12 and the audio data storage unit 13. The microphone unit 11 may be a receiving unit that receives audio data.

  Here, it is assumed that additional data is added to the input sound. FIG. 2 is a diagram illustrating an example of an encode frame. An echo signal delayed by a predetermined time is added to the original signal shown in FIG. It is possible to determine which data is added based on the difference in the predetermined time.

  One encoded frame shown in FIG. 2 is a frame in which an echo signal indicating one additional data is added to the original signal. Further, by adding an echo signal delayed by an arbitrary Δt at every t1 interval, one additional data is extracted every t1.

  Returning to FIG. 1, the audio data counting unit 12 counts the number of audio data acquired from the microphone unit 11. At this time, the audio data to be counted is a decoded frame in which the update interval t1 is divided into a plurality.

  FIG. 3 is a diagram illustrating an example of a decoded frame. As shown in FIG. 3, the decode frame is, for example, one frame obtained by dividing one encode frame into a plurality of pieces. When the number of decoded frames reaches a threshold value or more, for example, the audio data count unit 12 notifies the calculation unit 14 that data that can be calculated is stored. The threshold is, for example, the number of decoded frames included in one encoded frame.

  Further, one decode frame is, for example, several tens of msec (millisec), and one encode frame is, for example, 16 decode frames. The size of the decode frame and the size of the encode frame are merely examples, and are not limited to this example.

  When the calculation unit 14 receives the notification from the audio data count unit 12, the calculation unit 14 reads the audio data from the audio data storage unit 13 and calculates a cepstrum for each decoded frame. The calculation unit 14 outputs the cepstrum calculation result of each decoded frame to the decoding unit 15.

  The decoding unit 15 obtains a delay time corresponding to the peak value interval based on the cepstrum calculation result acquired from the calculation unit 14.

  FIG. 4 is a diagram illustrating an example of a cepstrum calculation result. As shown in FIG. 4, a cepstrum calculation result as shown in FIG. 4 is obtained for one decoded frame. The interval to the peak value of quefrency corresponds to the delay time of the echo signal.

  Returning to FIG. 1, the decoding unit 15 decodes the additional data based on the obtained delay time. The decoding unit 15 holds a correspondence table between the delay time and the additional data, decodes the delay time into additional data every time the delay time is acquired from the calculation unit 14, and outputs a decoding result indicating the additional data to the determination unit 16. Therefore, the decoding unit 15 can extract additional data for each decoded frame.

  The determination unit 16 acquires a decoding result from the decoding unit 15 and determines one additional data for one update interval based on the decoding result. It is assumed that the update interval of the additional data is preset in the sound processing device 1. Details of the determination unit 16 will be described with reference to FIG. The determination unit 16 outputs the determined additional data to the output unit 17.

  The output unit 17 outputs the additional data acquired from the determination unit 16 to a subsequent processing unit. The subsequent processing unit is, for example, a display unit. Thereby, the user can grasp the data added to the audio data by displaying the additional data.

<Function of determination unit>
FIG. 5 is a block diagram illustrating an example of the function of the determination unit 16 according to the first embodiment. The determination unit 16 illustrated in FIG. 5 includes a determination unit 101 for determining the first additional data, and a determination unit 102 for determining the second and subsequent additional data.

  The determination unit 101 includes a continuous count unit 111 and an additional data first determination unit 112. The continuous number counting unit 111 acquires, for example, the decoding result of each decoding frame in the first encoding frame from the decoding unit 15 and counts the number of decoding frames followed by the same decoding result (the same additional data). The continuous number counting unit 111 outputs the continuous number to the additional data first determination unit 112 and the center calculation unit 121.

  The additional data first determination unit 112 determines whether or not the continuous number obtained from the continuous number counting unit 111 is equal to or greater than a predetermined value. Here, the predetermined value is N, and N is determined in advance based on the update interval t1 of the additional data. The maximum value that N can take is the number obtained by subtracting the number of frames for data switching fade from the number of decoded frames in the encoded frame. Therefore, N is set to a value smaller than this maximum value.

  When the number of consecutive times is N or more, the additional data first determination unit 112 determines the continuous additional data as predetermined data added to the encoded frame. The additional data first determination unit 112 outputs the determined additional data to the output unit 17.

  Thereby, it is not necessary to adjust the update timing of the additional data and the read timing of the audio data, and the additional data can be appropriately extracted using the decode frame whose read timing is determined in advance.

  When the determination of the first additional data is completed, the determination unit 16 determines the second and subsequent additional data using the determination unit 102. Therefore, the decoding result of the decoding unit 15 corresponding to the second and subsequent encoded frames is input to the determination unit 102. For switching the decoding result input, for example, a switch or the like may be used.

  The determination unit 102 includes a center calculation unit 121, a first determination unit 122, and an additional data second determination unit 123. The center calculation unit 121 obtains the center of the continuous number obtained from the continuous number counting unit 111. For example, the center calculation unit 121 calculates the center time of the decoded frames in which the same decoding result is continuous. The center calculation unit 121 outputs the obtained center time to the first determination unit 122.

  The first determination unit 122 adds the update interval of the additional data to the center time acquired from the center calculation unit 121. The first determination unit 122 determines a predetermined number of frames centering on the time after the addition as determination positions for subsequent additional data. The predetermined number is N, for example, but is not limited to N, and an appropriate value may be set. The first determination unit 122 notifies the additional data second determination unit 123 of a predetermined number of frames included in the determined determination position.

  The additional data second determination unit 123 determines additional data using the frame at the determination position determined by the first determination unit 122. The additional data second determination unit 122 determines the additional data extracted most from the decoding results of the predetermined number of frames, and outputs the additional data extracted most to the output unit 17.

  The additional data second determination unit 123 uses a frame included in the determination position determined by the first determination unit 122 for determining the second and subsequent additional data.

  As a result, in the second and subsequent additional data determination processing, additional data can be determined using a decode frame near the center of the update interval, so that the accuracy of additional data extraction can be improved. In addition, since it is not necessary to count the number of consecutive times for the second and subsequent additional data determination processing, the processing amount can be reduced compared to the first additional data determination processing.

<Example of additional data determination processing>
Next, an example of the additional data determination process in the first embodiment will be described. FIG. 6 is a diagram for explaining the additional data determination processing according to the first embodiment. The additional data En11 to 14 shown in FIG. 6 represent an encoded frame in which the additional data B to E are encoded. In the example shown in FIG. 6, it is assumed that decoding is performed from the additional data B.

  Den (n = 101 to) shown in FIG. 6 represents a decoded frame. In the example shown in FIG. 6, it is assumed that the decoding result by the decoding unit 15 is “A” for De101 and “B” for De102 to 107. The continuous number counting unit 111 sets the number of continuous times to 6 because the decoding results are continuous with De 102 to 107 as “B”. Here, the predetermined value N is set to 3, for example.

  The additional data first determination unit 112 outputs the decoding result “B” to the output unit 17 because the number of consecutive times is equal to or greater than the predetermined value N.

  Next, the center calculation part 121 calculates | requires the center T0 of the continuous frequency 6. FIG. The center T0 is, for example, the center time of the decoded frames De102 to 107.

  The first determination unit 122 adds the update interval t1 of the additional data to the center time T0, and calculates the center time T1 of the next frame determination position. The first determination unit 122 determines a predetermined number N of frames centering on a frame including the update interval T1.

  The additional data second determination unit 123 determines the most extracted additional data based on the decoding result of a predetermined number N of frames including the time T1. Here, since the additional data “C” is three, the additional data “C” is output to the output unit 17.

  For the subsequent additional data determination, the first determination unit 122 adds the update interval t1 to the time T1, and calculates the center time T2 of the next frame determination position. The additional data second determination unit 123 determines the most extracted additional data from the decoding result of the predetermined number N of frames including the time T2. Here, the additional data “D” is output to the output unit 17.

  The center calculation unit 121 calculates the center time of a predetermined frame used for determining each additional data, and the first determination unit 122 sets a predetermined number of frames centered on the frame including the center time acquired from the center calculation unit 121. A frame may be determined.

  In this way, if the center time T0 of the update interval of the first additional data is estimated and then the update interval t1 is added, the additional data can be determined near the center of the update interval, and the additional data Can be appropriately extracted.

<Operation>
Next, the operation of the sound processing apparatus 1 in the first embodiment will be described. FIG. 7 is a flowchart illustrating an example of processing of the sound processing device 1 according to the first embodiment. In step S <b> 101 shown in FIG. 7, the microphone unit 11 receives the audio data and outputs it to the audio data count unit 12 and the audio data storage unit 13.

  In step S102, the audio data count unit 12 determines whether the required number of decoded frames has been received. If the required number of decoded frames has been received (step S102—YES), the process proceeds to step S103. If the required number of decoded frames has not been received (step S102—NO), the process returns to step S101.

  In step S103, the calculation unit 14 calculates a cepstrum for each decoded frame. The calculation unit 14 obtains a delay time from the cepstrum calculation result and outputs it to the decoding unit 15.

  In step S104, the decoding unit 15 detects a peak from the cepstrum calculation result and obtains a delay time of the echo signal. The decoding unit 15 acquires additional data corresponding to the obtained delay time from the correspondence table. The correspondence table associates the delay time with the additional data.

  In step S105, the continuous number counting unit 111 of the determination unit 16 counts the continuous number of decoded frames that are the same decoding result.

  In step S106, the additional data first determination unit 112 determines whether or not the number of consecutive times is N or more. If the number of continuous times is N or more (step S106—YES), the process proceeds to step S107. If the number of continuous times is less than N (step S106—NO), the process returns to step S101.

  In step S107, the output unit 17 outputs the additional data indicated by the decoding result having the number of consecutive times of N or more.

  In step S108, the center calculation unit 121 and the first determination unit 122 determine the determination position of the next decoded frame.

  In step S <b> 109, the microphone unit 11 receives audio data and outputs it to the audio data counting unit 12 and the audio data storage unit 13.

  In step S110, the audio data count unit 12 determines whether the required number of decoded frames has been received. If the required number of decoded frames is received (step S110-YES), the process proceeds to step S111. If the required number of decoded frames is not received (step S110-NO), the process returns to step S109.

  In step S111, the calculation unit 14 calculates a cepstrum for each decoded frame. The calculation unit 14 obtains a delay time from the cepstrum calculation result and outputs it to the decoding unit 15.

  In step S112, the decoding unit 15 detects a peak from the cepstrum calculation result, and obtains a delay time of the echo signal. The decoding unit 15 acquires additional data corresponding to the obtained delay time from the correspondence table. The correspondence table associates the delay time with the additional data.

  Steps S109 to S112 have been described after step S108 for convenience of explanation. Actually, however, the next audio data is received in step S109 following step S101, and the processing after step S110 is performed.

  In step S113, the additional data second determination unit 123 determines whether or not the decoding result is a determination target. For example, the additional data second determination unit 123 determines whether the decoding result of the decoded frame at the determination position determined by the first determination unit 122 is obtained. If the decoding result is a determination target (step S113—YES), the process proceeds to step S114. If the decoding result is not a determination target (step S113—NO), the process returns to step S109, and the next audio data is received.

  In step S114, the additional data second determination unit 123 counts the number of decoding results to be determined.

  In step S115, the additional data second determination unit 123 determines whether or not the number of counts to be determined is N. If the number of counts is N (step S115—YES), the process proceeds to step S116. If the number of counts is not N (step S115—NO), the process returns to step S109 to receive the next audio data.

  In step S116, the additional data second determination unit 123 determines a majority of the additional data extracted by taking the majority of N decoding results.

  In step S117, the additional data second determination unit 123 resets the counted number.

  After the processing of step S117, the process proceeds to step S107, and the output unit 17 outputs additional data that is the result of the majority decision.

  Thereafter, the processing of steps S107 to S117 is repeated, and the determined additional data is output in order.

  As described above, according to the first embodiment, it is possible to improve the extraction accuracy of additional data with respect to the audio data subjected to echo hiding while suppressing the processing amount.

[Example 2]
Next, the sound processing apparatus according to the second embodiment will be described. The sound processing apparatus according to the second embodiment can appropriately extract additional data even when the first additional data is continuously added to a plurality of encoded frames.

<Configuration>
Since the configuration of the sound processing apparatus in the second embodiment is the same as that of the sound processing apparatus in the first embodiment, the description thereof is omitted. In the case of using the configuration of the sound processing apparatus in the second embodiment, description will be made using the same reference numerals as those shown in FIG.

<Function of determination unit>
Next, the function of the determination part 16 in Example 2 is demonstrated. FIG. 8 is a block diagram illustrating an example of the function of the determination unit 16 according to the second embodiment. The determination unit 16 illustrated in FIG. 8 includes a determination unit 201 for determining the first additional data and a determination unit 202 for determining the second and subsequent additional data.

  The determination unit 201 includes a continuous number counting unit 211 and an additional data first determination unit 212. Similar to the first embodiment, the continuous number counting unit 211 acquires the decoding result from the decoding unit 15 and counts the number of times that the same decoding result continues. The continuous count unit 211 outputs the continuous count to the additional data first determination unit 212 and the center calculation unit 221.

  The additional data first determination unit 212 determines whether or not the continuous number obtained from the continuous number counting unit 211 exceeds a predetermined multiple of the number of decoded frames in the encoded frame. Further, the additional data first determination unit 212 may determine whether or not the decoding frame time corresponding to the continuous number of times exceeds a predetermined multiple of the encoding frame update interval.

  This determination is performed to determine whether or not the first additional data is continuously added to a plurality of encoded frames. When the number of consecutive times exceeds a predetermined multiple, the additional data first determination unit 212 adjusts (the number of consecutive times / the number of decoded frames included in the encoded frame) or (the time of the decoded frame for the number of consecutive times / the update interval of the encoded frame). An integer value M obtained by adding 1 to the numerical value is calculated. The additional data first determination unit 212 outputs the additional data indicated by the decoding result to the output unit 17 by the integer value M.

  When the number of consecutive times does not exceed a predetermined multiple, the additional data first determination unit 212 determines whether or not the number of consecutive times is equal to or greater than a predetermined value N as in the first embodiment.

  Thereby, even when the additional data to be determined first is continuously added to a plurality of encoded frames, the additional data can be appropriately extracted.

  When the determination of the first additional data is completed, the determination unit 16 determines the second and subsequent additional data using the determination unit 202. Therefore, the decoding result of the decoding unit 15 corresponding to the second and subsequent encoded frames is input to the determination unit 202. For switching the decoding result input, for example, a switch or the like may be used.

  The determination unit 202 includes a center calculation unit 221, a second determination unit 222, and an additional data second determination unit 223. The center calculation unit 221 determines the center of the continuous number of times acquired from the continuous number of times counting unit 211. For example, the center calculation unit 221 calculates the center time of the decoded frames in which the same decoding result is continued. The center calculation unit 221 outputs the obtained center time to the second determination unit 222.

  The second determination unit 222 adds the update interval of the additional data to the center time acquired from the center calculation unit 221. When the center time is a center when the center time exceeds a predetermined multiple, and M is an odd number, the second determination unit 222 determines that the acquired center is near the center of the update interval of the encoded frame, and sets the center time as the center time. The time obtained by adding the ((M + 1) / 2) times update interval is calculated.

  Further, when M is an even number, the second determination unit 222 determines that the acquired center is near the update timing of the encoded frame, and adds the half of the update interval to this center to obtain the vicinity of the center of the update interval. . The second determination unit 222 calculates a time obtained by adding (M / 2) times the update interval to the center obtained by adding half the update interval.

  Therefore, the second determination unit 222 calculates a time obtained by adding an update interval of ((M + 1) / 2) times to the acquired center regardless of whether the integer value M is an even number or an odd number. The second determination unit 222 once adds ((M + 1) / 2) times update intervals, and then adds 1 time update intervals.

  The second determination unit 222 determines a predetermined number of frames centered on the time after the addition as determination positions for subsequent additional data. The predetermined number is N, for example, but is not limited to N, and an appropriate value may be set. The second determination unit 222 notifies the additional data second determination unit 223 of the predetermined number of frames included in the determined determination position.

  The additional data second determination unit 223 determines additional data using the frame at the determination position determined by the second determination unit 222. The additional data second determination unit 222 determines the additional data extracted the most from the decoding results of the predetermined number of frames, and outputs the additional data extracted the most to the output unit 17.

  The additional data second determination unit 223 uses a frame included in the determination position determined by the second determination unit 222 for determining the second and subsequent additional data.

  As a result, even when the first additional data is continuously added to a plurality of encoded frames, the determination of the second and subsequent additional data is appropriately performed without increasing the processing amount as in the first embodiment. Can be done.

<Example of additional data determination processing>
Next, an example of the additional data determination process in the second embodiment will be described. FIG. 9 is a diagram for explaining additional data determination processing according to the second embodiment. The additional data En21 to 24 shown in FIG. 9 represents an encoded frame in which the additional data B, D, and E are encoded. In the example shown in FIG. 9, it is assumed that decoding is performed from the additional data B.

  Den (n = 201) shown in FIG. 9 represents a decoded frame. In the example shown in FIG. 9, it is assumed that the decoding result by the decoding unit 15 is “A” for De201 and “B” for De202 to 214. The continuous number counting unit 211 sets the number of continuous times to 12 because the decoding results continue to be “B” in De 202 to 214. At this time, if the number of decode frames included in one encode frame is 8, the number of consecutive times exceeds the number of “8”.

  Therefore, the additional data first determination unit 212 calculates the integer value M = 2 by adding 1 to the integer value (quotient) 1 of (12/8). The additional data first determination unit 212 outputs the additional data “B” indicated by the decoding result of 8 consecutive times to the output unit 17 for M = 2 times.

  Next, the center calculation part 221 calculates | requires the center T0 of continuous frequency | count. The center T0 shown in FIG. 9 is near the update timing of the encode frames En21 and En22 because M = 2.

First, the second determination unit 222 adds half (t1 / 2) of the update interval of the additional data to the center time T0 to obtain the vicinity of the center of the update interval. Next, the second determination unit 222 adds (M / 2) × t1 to the time (T0 + (t1 / 2)). That is, the center time T1 of the next frame determination position is calculated using the following equation.
T1 = T0 + ((M + 1) / 2) × t1
The second determination unit 222 determines a predetermined number N of frames centering on the frame including the update interval T1.

  The additional data second determination unit 223 determines the additional data extracted most by the decoding result of the predetermined number N of frames including the time T1. Here, since the additional data “D” is three, the additional data “D” is output to the output unit 17.

  For the subsequent additional data determination, the second determination unit 222 adds the update interval t1 to the time T1, and calculates the center time T2 of the next frame determination position. The additional data second determination unit 223 determines the additional data extracted most by the decoding result of the predetermined number N of frames including the time T2. Here, the additional data “E” is output to the output unit 17.

  The center time of a predetermined frame used for determining each additional data is calculated by the center calculation unit 221, and the second determination unit 222 has a predetermined number of frames centered on the frame including the center time acquired from the center calculation unit 221. A frame may be determined.

  Thereby, even when the first additional data is continuously added to a plurality of encoded frames, the predetermined number of frames used for determination of the additional data can be appropriately determined.

<Operation>
Next, the operation of the sound processing apparatus according to the second embodiment will be described. FIG. 10 is a flowchart illustrating an example of processing performed by the sound processing apparatus according to the second embodiment. The processing in steps S201 to S206 shown in FIG. 10 is the same as the processing in steps S101 to S106 shown in FIG.

  In step S207, the additional data first determination unit 212 rounds up the decoding frame time corresponding to the continuous number of times to an integer value M times the encoding frame update interval.

  In step S208, the output unit 17 outputs the M additional data determined by the additional data first determination unit 212.

  In step S209, the center calculation unit 221 and the second determination unit 222 determine the determination position of the next decoded frame. The determination position of the second additional data is a predetermined number of frames centered at the central time T0 + ((M + 1) / 2) × update interval t1.

  The processing of steps S210 to S218 is the same as the processing of steps S109 to S117 shown in FIG.

  After the process of step S218, the process proceeds to step S208, and the output unit 17 outputs additional data that is the result of the majority decision.

  Thereafter, the processing of steps S208 to S218 is repeated, and the determined additional data is output in order. When determining the third and subsequent additional data in step S209, the update interval t1 may be added to the center time T1 for the second additional data.

  As described above, according to the second embodiment, it is possible to improve the extraction accuracy of the additional data with respect to the audio data subjected to echo hiding while suppressing the processing amount. Further, according to the second embodiment, even when the first additional data is continuously added to a plurality of encoded frames, the additional data can be appropriately extracted.

[Example 3]
Next, a sound processing apparatus according to the third embodiment will be described. The sound processing apparatus according to the third embodiment can correct the central time used for determining the second and subsequent additional data.

<Configuration>
Since the configuration of the sound processing apparatus in the third embodiment is the same as that of the sound processing apparatus in the first embodiment, the description thereof is omitted. When the configuration of the sound processing apparatus in the third embodiment is used, the description will be made using the same reference numerals as those shown in FIG.

<Function of determination unit>
Next, the function of the determination part 16 in Example 3 is demonstrated. FIG. 11 is a block diagram illustrating an example of the function of the determination unit 16 according to the third embodiment. The determination unit 16 illustrated in FIG. 11 includes a determination unit 301 for determining the first additional data, and a determination unit 302 for determining the second and subsequent additional data.

  The determination unit 301 includes a continuous number counting unit 311 and an additional data first determination unit 312. Since the continuous number counting unit 311 and the additional data first determination unit 312 are the same as the continuous number counting unit 111 and the additional data first determination unit 112 described in the first embodiment, the description thereof is omitted.

  The determination unit 302 includes a center calculation unit 321, a third determination unit 322, and an additional data third determination unit 323. The center calculation unit 321 is the same as the center calculation unit 121 described in the first embodiment, and a description thereof will be omitted.

  The third determination unit 322 adds the update interval of the additional data to the center time acquired from the center calculation unit 321. The third determination unit 322 determines a predetermined number of frames centering on the time after the addition as determination positions for subsequent additional data. The predetermined number is N, for example, but is not limited to N, and an appropriate value may be set.

  The third determining unit 322 sets the determined predetermined number of frames as the first group, sets the first group as one decoded frame, sets the group of decoded frames shifted forward as the second group, and sets the first group as A group of decode frames shifted later by one decode frame is defined as a third group.

  The third determination unit 322 notifies the additional data third determination unit 323 of the determined three groups of the predetermined number of frames. Note that the number of groups is not limited to three.

  The additional data third determination unit 323 determines additional data using the frames at the determination positions of the three counties determined by the third determination unit 322. The additional data third determination unit 323 determines additional data extracted most by decoding results of a predetermined number of frames in each group.

  The additional data third determination unit 323 decides the majority of the three groups with the same number of additional data extracted. The additional data third determination unit 323 outputs the additional data having the largest number of extractions to the output unit 17. If the first group is included in the group having the largest number of extractions of the same additional data, the additional data third determination unit 323 determines the subsequent additional data determination position based on the central time of the first group. Let me decide.

  If the first group is not included in the group with the largest number of extractions of the same additional data, the additional data third determination unit 323 determines the center time of the county with the largest number of extractions as subsequent additional data. The third determination unit 322 is notified so that the position is used as a reference. Note that the additional data third determination unit 323 may use the central time of one of the groups set in advance when the number of extractions is the largest in both the second group and the third group.

  Thereby, the center time used for determination of additional data can be corrected. This correction is useful for preventing this deviation from accumulating because there is a slight deviation between the center time of the actual encoding frame and the determined center time.

<Example of additional data determination processing>
Next, an example of the additional data determination process in the third embodiment will be described. FIG. 12 is a diagram for explaining the additional data determination process according to the third embodiment. Additional data En31 to 34 shown in FIG. 12 represents an encoded frame in which each additional data B to E is encoded. In the example shown in FIG. 12, it is assumed that the additional data B is decoded.

  Den (n = 301 to) shown in FIG. 12 represents a decoded frame. In the example illustrated in FIG. 12, the decoding result by the decoding unit 15 is, for example, that De301 is “A” and De302 to 307 are “B”. The continuous number counting unit 311 sets the number of continuous times to 6 because the decoding results continue to be “B” in De 302 to 307. Here, the predetermined value N is set to 3, for example.

  The additional data first determination unit 312 outputs the decoding result “B” to the output unit 17 because the number of consecutive times is equal to or greater than the predetermined value N.

  Next, the center calculation part 321 calculates | requires the center T0 of the continuous frequency 6. FIG. The center T0 is, for example, the center time of the decode frames De302 to 307.

  The third determination unit 322 adds the update interval t1 of the additional data to the center time T0, and calculates the center time T1 of the next frame determination position. The third determination unit 322 determines a predetermined number N frames as the first group around the frame including the update interval T1.

  The third determining unit 322 determines the second group shifted from the first group by one decoded frame and the third group shifted from the first group by one decoded frame. For example, in the example shown in FIG. 12, De310 to 312 are the first group, De309 to 311 are the second group, and De311 to 313 are the third group.

  The additional data third determination unit 323 determines a majority by decoding the predetermined number N of frames for each group. For example, the additional data third determination unit 323 determines using the same number of additional data extracted. Here, since the additional data “C” is extracted three by three in any group, the additional data “C” is output to the output unit 17.

  For the subsequent additional data determination, the third determination unit 322 adds the update interval t1 to the time T1, and calculates the center time T2 of the next frame determination position. The third determination unit 322 determines the frames of the first group to the third group based on the central time T2.

  The additional data third determination unit 323 determines the additional data “D” and outputs it to the output unit 17 because three additional data “D” are extracted from the third group. Here, the extraction number “3” of the additional data “D” of the third group is the extraction number “2” of the additional data “D” of the first group, and the extraction number “2” of the additional data “C” of the second group. Is bigger than

  Therefore, the additional data third determination unit 323 notifies the third determination unit 322 of the center of the predetermined number of decode frames in the third group as the center time T2 '. Upon obtaining the center time T2 ', the third determination unit 322 adds the update interval t1 to T2' and calculates the center time T3 of the next frame determination position.

  The center calculation unit 321 calculates the center time of a predetermined frame used for determining each additional data, and the third determination unit 322 determines the predetermined number of frames of each group based on the center time acquired from the center calculation unit 321. May be determined.

  Thereby, in the determination of the second and subsequent additional data, the center time can be corrected, and more appropriate additional data can be extracted.

<Operation>
Next, the operation of the sound processing apparatus according to the third embodiment will be described. FIG. 13 is a flowchart illustrating an example of processing performed by the sound processing apparatus according to the third embodiment. The processes in steps S301 to S314 shown in FIG. 13 are the same as the processes in steps S101 to S114 shown in FIG.

  In step S315, the additional data third determination unit 323 determines whether or not the number of counts to be determined is N + 2. If the number of counts is N + 2 (step S315—YES), the process proceeds to step S316, and if the number of counts is not N + 2 (step S315—NO), the process returns to step S309 to receive the next audio data.

  In step S316, the additional data third determination unit 323 determines the majority of the additional data extracted by taking the majority of the N decoding results of the first group.

  In step S317, the additional data third determination unit 323 determines the majority of additional data extracted by taking the majority of the N decoding results of the second group.

  In step S318, the additional data third determination unit 323 determines the majority of the additional data extracted by taking the majority of the N decoding results of the third group.

  In step S319, the additional data third determination unit 323 determines the group having the largest number of extractions of the same additional data. The additional data third determination unit 323 outputs the additional data extracted most in the determined group to the output unit 17.

  In step S320, the additional data third determination unit 323 resets the counted number.

  After the process of step S320, the process proceeds to step S307, and the output unit 17 outputs additional data that is the result of the majority decision.

  Thereafter, the processes in steps S307 to S320 are repeated, and the determined additional data is output in order. When determining the third and subsequent additional data in step S308, the update interval t1 may be added to the central time of the group determined in step S319.

  As described above, according to the third embodiment, it is possible to improve the extraction accuracy of the additional data with respect to the audio data subjected to echo hiding while suppressing the processing amount. In addition, the central time used for determining the second and subsequent additional data can be corrected, and the additional data extraction accuracy can be further improved.

[Example 4]
Next, the sound processing device 4 according to the fourth embodiment will be described. The sound processing device 4 according to the fourth embodiment achieves power saving by acquiring only audio data used for determination of additional data.

<Configuration>
FIG. 14 is a block diagram illustrating an example of the configuration of the sound processing device 4 according to the fourth embodiment. In the configuration illustrated in FIG. 14, the same components as those illustrated in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  When the determination of the additional data is completed, the determination unit 21 notifies the power control unit 22 of power off. Further, the determination unit 21 sets the time until the decode frame reading start time used for determination of the next additional data in the timer unit 23.

  When the power control unit 22 is notified of the power off from the determination unit 21, the power control unit 22 turns off the power to the microphone unit 11, the audio data count unit 12, the audio data storage unit 13, the calculation unit 14, and the decoding unit 15.

  When the power supply control unit 22 is notified of the power supply instruction from the timer unit 23, the power supply control unit 22 supplies power to the microphone unit 11, the audio data count unit 12, the audio data storage unit 13, the calculation unit 14, and the decoding unit 15. Supply. Therefore, the power supply control unit 22 has a control function that prevents the processing of each unit including the audio data reading processing from being performed.

  The timer unit 23 has a built-in clock, and instructs the power supply control unit 22 to supply power when the time notified from the determination unit 21 has elapsed.

<Function of determination unit>
The determination part 21 in Example 4 should just have the function in any one of Examples 1-3 except the function mentioned above. The determination unit 21 uses any one of the first to third embodiments to calculate the time until the decode frame reading start time used for determination of the next additional data, and notifies the timer unit 23 of this time.

  As a result, only the decode frame for determining the additional data needs to be processed, so that power consumption can be suppressed.

<Example of additional data determination processing>
Next, an example of additional data determination processing according to the fourth embodiment will be described. FIG. 15 is a diagram for explaining additional data determination processing according to the fourth embodiment. In the example illustrated in FIG. 15, the determination process of the determination unit 21 will be described using the reference numerals in FIG. 5 described in the first embodiment.

  Additional data En41 to 44 shown in FIG. 15 represents an encoded frame in which each additional data B to E is encoded. In the example shown in FIG. 15, it is assumed that the additional data B is decoded.

  Den (n = 401 to) shown in FIG. 15 represents a decoded frame. In the example illustrated in FIG. 15, it is assumed that the decoding result by the decoding unit 15 is “A” for De 401 and “B” for De 402 to 407. The continuous number counting unit 111 sets the number of continuous times to 6 because the decoding results are continuous with “B” in De 402 to 407. Here, the predetermined value N is set to 3, for example.

  The additional data first determination unit 112 outputs the decoding result “B” to the output unit 17 because the number of consecutive times is equal to or greater than the predetermined value N.

  Next, the center calculation part 121 calculates | requires the center T0 of the continuous frequency 6. FIG. The center T0 is, for example, the center time of the decode frames De402 to 407.

  The first determination unit 122 adds the update interval t1 of the additional data to the center time T0, and calculates the center time T1 of the next frame determination position. The first determination unit 122 determines a predetermined number N of frames centering on a frame including the update interval T1. The determination unit 21 notifies the power supply control unit 22 of power-off when the determination processing of the De408 decode frame is completed. Also, the determination unit 21 sets the time until the start time for reading the De409 decode frame in the timer unit 23. The determination unit 21 performs the same processing thereafter, and notifies the power supply control unit 22 of power-off and sets the time to the timer unit 23.

  Thereby, in the determination of the next additional data, the audio data is not processed for the decoded frames other than the decoded frames of De409 to 411, and power saving can be realized.

<Operation>
Next, the operation of the sound processing apparatus 1 in the fourth embodiment will be described. FIG. 16 is a flowchart illustrating an example of processing of the sound processing device 4 according to the fourth embodiment. Note that the process shown in FIG. 16 is a process when the determination process of the first embodiment is performed.

  The processes in steps S401 to S408 shown in FIG. 16 are the same as the processes in steps S101 to S108 shown in FIG.

  In step S409, the determination unit 21 calculates the time from the current time to the reading start time of the next decoded frame, and sets the time in the timer unit 23.

  In step S410, the determination unit 21 notifies the power control unit 22 of power off. Thereby, the unnecessary power supply of each part can be cut | disconnected.

  In step S411, the timer unit 23 determines whether the set time has elapsed. If the set time has elapsed (step S411-YES), the process proceeds to step S412. If the set time has not elapsed (step S411-NO), the process returns to step S411.

  In step S <b> 412, the power supply control unit 22 starts supplying power to each unit that has been turned off. As a result, the additional data determination process resumes.

  The processing in steps S413 to S420 is the same as the processing in S109 to S117 shown in FIG.

  As described above, according to the fourth embodiment, it is possible to improve the extraction accuracy of additional data and reduce power consumption with respect to the audio data subjected to echo hiding while suppressing the processing amount.

[Example 5]
FIG. 17 is a block diagram illustrating an example of hardware of the mobile terminal device 5 according to the fifth embodiment. The mobile terminal device 5 includes an antenna 501, a wireless unit 502, a baseband processing unit 503, a control unit 504, a terminal interface unit 505, a main storage unit 506, an auxiliary storage unit 507, a microphone 508, and a display unit 509.

  The antenna 501 transmits the radio signal amplified by the transmission amplifier and receives the radio signal from the base station. Radio section 502 performs D / A conversion on the transmission signal spread by baseband processing section 503, converts it to a high-frequency signal by orthogonal modulation, and amplifies the signal by a power amplifier. Radio section 702 amplifies the received radio signal, A / D converts the signal, and transmits the signal to baseband processing section 703.

  The baseband unit 503 performs baseband processing such as addition of an error correction code of transmission data, data modulation, spread modulation, despreading of a received signal, determination of a reception environment, threshold determination of each channel signal, error correction decoding, and the like. .

  The control unit 504 performs wireless control such as transmission / reception of control signals. Further, the control unit 504 executes a sound processing program stored in the auxiliary storage unit 507 or the like, and performs the sound processing described in each embodiment.

  The terminal interface unit 505 performs data adapter processing, interface processing with a handset, and an external data terminal.

  The main storage unit 506 is a ROM (Read Only Memory), a RAM (Random Access Memory) or the like, and stores or temporarily stores programs and data such as an OS (Operating System) and application software which are basic software executed by the control unit 504. It is a storage device to save.

  The auxiliary storage unit 507 is an HDD (Hard Disk Drive) or the like, and is a storage device that stores data related to application software or the like. The auxiliary storage unit 507 stores the above-described sound processing program.

  The microphone 508 converts the announcement added with the additional data into audio data of an electrical signal. The display unit 509 is, for example, an LCD (Liquid Crystal Display) or the like, and performs display according to display data input from the control unit 504. For example, the display unit 509 displays the extracted additional data.

  The functions of the units other than the microphone unit 11 and the audio data storage unit 13 of the sound processing apparatus of each embodiment can be realized by, for example, the control unit 504 and the main storage unit 506 as a work memory. The audio data storage unit 13 can be realized by the main storage unit 506, for example. The microphone unit 11 can be realized by a microphone 508, for example.

  In addition, a part of each part of the sound processing apparatus in each embodiment may be implemented by hardware and may be implemented by other software. For example, the microphone unit 11, the decoding unit 15, the audio data storage unit 13, and the like may be implemented by hardware, and the others may be implemented by software.

  As described above, according to the fifth embodiment, the mobile terminal device 5 can perform the additional data determination process in the first to fourth embodiments.

  In addition, the disclosed technology can be implemented not only in the mobile terminal device 5 but also in other devices. For example, the sound processing apparatus described above can be applied to any processing apparatus having a microphone, a receiving unit, and a control unit for inputting audio data to which additional data is added.

  Further, by recording a program for realizing the sound processing described in each of the above-described embodiments on a recording medium, the sound processing in each of the embodiments can be performed by a computer.

  It is also possible to record the program on a recording medium and cause the computer or portable terminal device to read the recording medium on which the program is recorded to realize the above-described sound processing. The recording medium is a recording medium for recording information optically, electrically or magnetically, such as a CD-ROM, flexible disk, magneto-optical disk, etc., and information is electrically recorded such as ROM, flash memory, etc. Various types of recording media such as a semiconductor memory can be used. The recording medium does not include a carrier wave.

  The devices described in the above embodiments, for example, add the same contents as the announcement to the in-car announcement in the train as additional data, and a person with hearing impairment displays the announcement indicated by the additional data on the display unit. Used when. Thereby, the apparatus of each embodiment can be applied to knowing the contents of the announcement.

  Although the embodiments have been described in detail, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope described in the claims. It is also possible to combine all or a plurality of the components of the above-described embodiments. Moreover, the embodiments described above can be combined.

In addition, the following additional remarks are disclosed regarding the above Example.
(Appendix 1)
A calculation for performing cepstrum calculation on each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed by a predetermined time And
A first determination unit that determines whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determines predetermined data for one update interval When,
An output unit for outputting the determined predetermined data;
A sound processing apparatus comprising:
(Appendix 2)
A center calculation unit for obtaining a center time of frames from which the same predetermined data is extracted continuously;
A first determination unit that adds the update interval to the determined central time and determines a predetermined number of frames used for extraction of the next additional data;
Appendix 1 further comprising: a second determination unit that determines the most extracted predetermined data based on the determined cepstrum calculation results of the predetermined number of frames and outputs the most extracted predetermined data to the output unit. The sound processing apparatus as described.
(Appendix 3)
The first determination unit includes:
Note 1 that when the time of frames from which the same predetermined data is continuously extracted exceeds a predetermined multiple of the update interval, the predetermined data is output to the output unit by the number of integers obtained by adding 1 to the predetermined multiple The sound processing apparatus as described.
(Appendix 4)
A center calculation unit for obtaining the center of a frame from which the same predetermined data is extracted continuously;
A second determining unit that adds (the integer value + 1) / 2 times the update interval to the determined center and determines a predetermined number of frames used for extraction of the next additional data;
Supplementary note 3 further comprising: a second determination unit that determines the most extracted predetermined data based on the determined cepstrum calculation results of the predetermined number of frames and outputs the most extracted predetermined data to the output unit. The sound processing apparatus as described.
(Appendix 5)
A center calculation unit for obtaining the center of a frame from which the same predetermined data is extracted continuously;
A third determination unit for adding a plurality of groups of a predetermined number of frames to be used for extraction of the next additional data by adding the update interval to the determined center;
A third determination unit for determining the most extracted predetermined data based on the cepstrum calculation results of a predetermined number of frames in each determined group, and outputting the most extracted predetermined data to the output unit; Prepared,
The center calculator is
The sound processing apparatus according to supplementary note 1, wherein a center of a frame of a group in which the predetermined data is extracted most is obtained.
(Appendix 6)
The sound processing device according to any one of appendices 2, 4, and 5, further comprising a control unit that controls not to read the audio data in a frame other than a predetermined number of frames used for extraction of the next additional data. .
(Appendix 7)
The echo signal is faded in and out before and after the update interval,
The sound processing apparatus according to any one of appendices 1 to 6, wherein the predetermined value is determined based on a number of decode frames with respect to a time obtained by excluding the fade-in and fade-out times from the update interval.
(Appendix 8)
Performs cepstrum calculation for each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed for a predetermined time,
Determining whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determining predetermined data for one update interval;
A sound processing method in which a computer executes a process of outputting the determined predetermined data.
(Appendix 9)
Performs cepstrum calculation for each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed for a predetermined time,
Determining whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determining predetermined data for one update interval;
A program for causing a computer to execute a process of outputting the determined predetermined data.

1, 4 Sound processing device 5 Portable terminal device 11 Microphone unit 12 Audio data counting unit 13 Audio data storage unit 14 Calculation unit 15 Decoding unit 16, 21 Determination unit 17 Output unit 22 Power supply control unit 23 Timer units 111, 211, 311 Continuous Number counting unit 112, 212, 312 Additional data first determination unit 121, 221, 321 Center calculation unit 122 First determination unit 123, 223 Additional data second determination unit 222 Second determination unit 322 Third determination unit 323 Additional data 3 determination unit 504 control unit 506 main storage unit 507 auxiliary storage unit 508 microphone 509 display unit

Claims (6)

A calculation for performing cepstrum calculation on each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed by a predetermined time And
A first determination unit that determines whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determines predetermined data for one update interval When,
An output unit for outputting the determined predetermined data;
Of each frame, and the central calculation unit for a plurality of frames which the same predetermined data is extracted successively obtain the center time for the entire plurality of frames,
A first determination unit that adds the update interval to the determined central time and determines a predetermined number of frames used for extraction of the next additional data;
A second determination unit for determining the most extracted predetermined data based on the determined cepstrum calculation results of the predetermined number of frames, and outputting the most extracted predetermined data to the output unit;
A sound processing apparatus comprising: A calculation for performing cepstrum calculation on each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed by a predetermined time And
A first determination unit that determines whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determines predetermined data for one update interval When,
An output unit for outputting the determined predetermined data,
The first determination unit includes:
When the time of frames from which the same predetermined data is continuously extracted exceeds a predetermined multiple of the update interval, the predetermined data is output to the output unit by the number of integer values obtained by adding 1 to the predetermined multiple ,
A center calculation unit for obtaining a center for the whole of the plurality of frames for a plurality of frames from which the same predetermined data is continuously extracted,
A second determining unit that adds (the integer value + 1) / 2 times the update interval to the determined center and determines a predetermined number of frames used for extraction of the next additional data;
Sound processing further comprising: a second determination unit that determines the most extracted predetermined data based on the determined cepstrum calculation results of the predetermined number of frames and outputs the most extracted predetermined data to the output unit apparatus. A calculation for performing cepstrum calculation on each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed by a predetermined time And
A first determination unit that determines whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determines predetermined data for one update interval When,
An output unit for outputting the determined predetermined data;
Of each frame, and the central calculation unit for a plurality of frames which the same predetermined data is extracted successively obtain the center to the entire plurality of frames,
A third determination unit for adding a plurality of groups of a predetermined number of frames to be used for extraction of the next additional data by adding the update interval to the determined center;
A third determination unit for determining the most extracted predetermined data based on the cepstrum calculation results of a predetermined number of frames in each determined group, and outputting the most extracted predetermined data to the output unit; Prepared,
The center calculator is
A sound processing apparatus for obtaining a center of a group of frames from which the predetermined data is extracted most. The next is a predetermined number of frames other than the frames used for extraction of the additional data, the sound processing apparatus according to any one of claims 1 to 3 further comprising a control unit for controlling not to perform the reading of the audio data . Performs cepstrum calculation for each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed for a predetermined time,
Determining whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determining predetermined data for one update interval;
Outputting the determined predetermined data;
For each of the plurality of frames from which the same predetermined data is continuously extracted, a central time for the plurality of frames is obtained.
Adding the update interval to the determined central time to determine a predetermined number of frames used for extraction of the next additional data;
A sound processing method in which a computer executes a process of determining the most extracted predetermined data based on the determined cepstrum calculation results of a predetermined number of frames and outputting the most extracted predetermined data. Performs cepstrum calculation for each frame in which audio data having a length corresponding to the update interval is divided into a plurality of frames for audio data to which predetermined data is added at each update interval based on an echo signal delayed for a predetermined time,
Determining whether or not the number of consecutive frames having the same predetermined data extracted based on the cepstrum calculation result of each frame is equal to or greater than a predetermined value, and determining predetermined data for one update interval;
Outputting the determined predetermined data;
For each of the plurality of frames from which the same predetermined data is continuously extracted, a central time for the plurality of frames is obtained.
Adding the update interval to the determined central time to determine a predetermined number of frames used for extraction of the next additional data;
A program for causing a computer to execute a process of determining the most extracted predetermined data based on the determined cepstrum calculation results of a predetermined number of frames and outputting the most extracted predetermined data.

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