JP2009008843A - Acoustic signal playback device and acoustic signal playback method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic signal playback device for reducing degradation of viewing environment, even if an error occurs in the acoustic signal to be played back, when the acoustic signals of a plurality of channels are included. <P>SOLUTION: Acoustic data of the plurality of channels are held in a frame unit, and it is determined whether or not, an error occurs in the acoustic data of each channel in the frame. When the error is determined, the acoustic data of the channel having a defective frame, is replaced with a predetermined silence data. Then, an acoustic playback data for reproducing based on the acoustic data of each channel in adjacent frames and the silence data is generated, and the acoustic playback data is played back. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acoustic signal reproducing apparatus and an acoustic signal reproducing method for inputting and reproducing an encoded acoustic signal that continuously appears as a bit stream.

  For example, in a digital device such as a cellular phone terminal, a digital television receiver, or a digital audio device, when a sound is to be output, a bit stream of a digital sound signal compressed and encoded according to a predetermined standard is input and a decoder In many cases, the sound is reproduced by decoding the bit stream of the sound signal using. For example, AAC (Advanced Audio Coding) is used as a compression encoding standard for audio signals.

  In AAC compression encoding, an acoustic signal is converted from a time domain signal to a frequency domain signal using DCT (Discrete Cosine Transform), and then encoded with a high compression ratio using the characteristics of human hearing. Generate a bitstream of the signal.

  By the way, for example, when a mobile phone terminal tries to reproduce a bit stream of an acoustic signal received from another station via a wireless transmission path, the content of the bit stream is incorrect due to noise or the like generated on the wireless transmission path. Is likely to occur. If a bitstream containing an uncorrectable error is decoded as it is and output as sound, the continuity of the sound signal, which is originally a continuous signal waveform, cannot be maintained, so it changes to an unnatural signal waveform, As a result, noise (abnormal noise) that is annoying to the viewer appears in the output sound.

  Therefore, as one method for preventing the occurrence of such abnormal noise, special encoded data for reproducing a silence signal is prepared in advance on the apparatus, and an error of the input bit stream is detected. In the case of detection, it has been proposed to perform processing so that silence is output as sound by decoding special encoded data instead of the original bitstream in which an error has occurred (for example, Patent Document 1).

  If only one frame of the input bitstream is incorrect, data is interpolated using the frames before and after it, or if there is an error in consecutive frames, the last normal frame is It has been proposed to interpolate using the data or to use the data as much as possible when only a part of the data is wrong (for example, see Patent Document 2).

JP 2003-091294 A Japanese Patent Application Laid-Open No. 2004-361731

  However, there is a high possibility that the technology of Patent Document 2 cannot sufficiently suppress the generation of abnormal noise.

  In the technique of Patent Document 1, it is necessary to prepare in advance special encoded data to be used in place of the original bit stream in which an error has occurred, but compression encoding is performed based on a standard such as AAC. In order to process a bit stream of an acoustic signal, for example, encoded data of a plurality of independent patterns must be prepared as a silence signal in accordance with the difference in the number of channels and the sampling rate. It is inevitable that the amount of data to be held increases and the processing becomes complicated.

  Furthermore, although the bit stream to be reproduced may include independent plural channels of acoustic signals, the conventional technique outputs all channels even when an error occurs in only one channel. Since the sound is controlled to the silent state, when viewed from the viewer, the frequency of the silent state is high, and the quality of the viewing environment is more strongly felt.

  The present invention has been made in view of the above circumstances, and reduces the deterioration of the viewing environment when an error occurs in an audio signal to be reproduced when an audio signal of a plurality of channels is included. It is an object of the present invention to provide an acoustic signal reproducing device and an acoustic signal reproducing method that can be used.

  In order to achieve the above object, a first audio signal reproduction device of the present invention includes a data holding unit that holds channel information regarding a plurality of channels and content data having audio data corresponding to each channel in units of frames, An error determination unit that determines whether or not there is an error in the acoustic data of each channel in the frame, and if it is determined that there is an error, the acoustic data of the channel that is determined to have the error in the frame Silence data replacement unit for replacing with silence data, reproduction data generation unit for generating sound reproduction data for reproduction based on the sound data and the silence data of each channel in adjacent frames, and the sound reproduction And a reproducing unit for reproducing data.

  With this configuration, when multiple channels of audio signals are included, even if an error occurs in the audio signal to be reproduced, the data in the channel of the frame in which the error has occurred is replaced with silence data. Deterioration can be reduced. For example, sound data included in digital TV broadcast data or data recorded by digital TV broadcast can be silenced only in the corresponding channel. In addition, since silence data can be determined regardless of the difference in the number of channels related to the acoustic data to be reproduced and the difference in sampling rate, it is extremely easy to hold and generate silence data. Furthermore, it is not necessary to store a large amount of silence data, and it is not necessary to prepare a complicated electric circuit for generating silence data.

  In addition, the second acoustic signal reproduction device of the present invention has a data input unit that inputs the content data from an external content distribution device as streaming data.

  With this configuration, even when streaming data is distributed from an external content distribution device, the communication environment is poor, and even if some error occurs in some acoustic data, Only acoustic data can be confirmed.

  The third acoustic signal reproduction device of the present invention includes a domain conversion unit that converts frequency domain data to time domain data, and the data storage unit stores frequency domain acoustic data, and the error The determination unit determines whether or not there is an error in the frequency domain acoustic data, and the reproduction data generation unit converts the time domain acoustic data and silence of each channel in frames adjacent to each other after the conversion by the region conversion unit. The sound reproduction data is generated based on the data.

  With this configuration, for example, time domain reproduction data (acoustic reproduction) in which the frequency domain acoustic data input as streaming data is processed in the acoustic signal reproduction device to minimize the state of silence during content reproduction. Data) can be generated.

  In addition, the fourth acoustic signal reproduction device of the present invention has a content type determination unit that determines the type of the acoustic data, and the region conversion unit converts the acoustic data held in the data holding unit in the time domain. When the sound data replacement unit determines that the acoustic data is not data including audio data of a plurality of languages, the silence data replacement unit determines that there is the error in the frame. The sound data in the time domain of the channel is replaced with predetermined silence data in the time domain.

  With this configuration, for example, in the case of data other than audio data for bilingual broadcasting, by replacing the acoustic data of the channel of the frame with an error with silence data in the time domain, no abnormal sound is generated, and the viewing environment Therefore, it is possible to reproduce an acoustic signal so that the viewer does not feel the quality degradation.

  The fifth acoustic signal reproduction device of the present invention has a content type determination unit that determines the type of the acoustic data, and the silence data replacement unit is configured to output the acoustic data in a plurality of languages by the content type determination unit. When it is determined that the data includes the audio data of the above, the acoustic data of the frequency domain of the channel determined to have the error in the frame is replaced with predetermined silence data of the frequency domain, the domain conversion unit, Frequency domain acoustic data and silence data are converted to time domain data.

  With this configuration, for example, when two or more independent audio signals are simultaneously input as signals of a plurality of channels included in one bit stream, such as bilingual broadcast content, abnormal noise is generated independently for each channel. Suppression control can be implemented. Therefore, for example, when a bilingual broadcast content including main audio and sub audio is played back, and there is no error in the main audio data, and there is an error only in the sub audio data. Can reproduce the main sound as it is and silence only the sub sound. Therefore, if the viewer is listening only to the main audio, even if an error has occurred in the secondary audio data, it can continue to view the main audio that does not include abnormal sounds without being affected by it, The frequency of the silent state to be felt is reduced.

  In the sixth audio signal reproduction device of the present invention, the content data is streaming data or digital television broadcast data.

  With this configuration, for example, if the communication environment deteriorates during reception of a digital television broadcast and broadcast data cannot be received correctly, the error occurrence part is muted and the normal part data is reproduced. Is possible. For example, if an error occurs only in a channel that has English audio data while receiving Japanese and English bilingual data, only the channel that has English audio data will be silenced, It becomes possible to reproduce a channel having data as usual.

  The first acoustic signal reproduction method of the present invention includes a step of holding content data having channel information on a plurality of channels and acoustic data corresponding to each channel in a unit of frames in the acoustic signal reproduction device; Determining whether or not there is an error in the sound data of each channel; and if it is determined that there is an error, replace the sound data of the channel determined to have the error in the frame with predetermined silence data A step of generating sound reproduction data for reproduction based on the sound data and the silence data of each channel in frames adjacent to each other, and a step of reproducing the sound reproduction data. Yes.

  This method replaces the data in the channel of the frame in which the error occurred with silence data even if an error occurs in the audio signal to be reproduced when multiple channels of audio signals are included. Deterioration can be reduced. For example, sound data included in digital TV broadcast data or data recorded by digital TV broadcast can be silenced only in the corresponding channel. In addition, since silence data can be determined regardless of the difference in the number of channels related to the acoustic data to be reproduced and the difference in sampling rate, it is extremely easy to hold and generate silence data. Furthermore, it is not necessary to store a large amount of silence data, and it is not necessary to prepare a complicated electric circuit for generating silence data.

  According to the present invention, when a plurality of channels of audio signals are included, it is possible to reduce the deterioration of the viewing environment even when an error occurs in the audio signal to be reproduced.

  In particular, when a bitstream error occurs, the time domain acoustic signal input to the time domain windowing processing unit is replaced with predetermined time domain silence data or input to the frequency-time domain conversion unit. Since the frequency domain acoustic signal is replaced with the frequency domain silence data determined in advance, it is necessary to prepare various patterns of silence data corresponding to the difference in the number of channels and the sampling rate regarding the bit stream to be reproduced. It is very easy to hold and generate time domain silence data or frequency domain silence data. That is, it is not necessary to store a large amount of silence data, and it is not necessary to prepare a complicated electric circuit for generating silence data.

  An acoustic signal reproduction device and an acoustic signal reproduction method according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing an example of the configuration of an acoustic signal reproduction device according to an embodiment of the present invention.

  Here, it is assumed that a bit stream (data string) of an audio signal compressed and encoded according to the AAC (Advanced Audio Coding) standard is input, the data string is processed, and the processed audio signal is reproduced. Yes. That is, the input bit stream SG1 input to the audio signal reproduction device 100 is an audio signal that is compression-encoded according to the AAC standard.

  The acoustic signal reproduction device 100 includes a bitstream interpretation unit 10 with a correction function, a frequency domain-time domain conversion unit 20, a time domain windowing unit 30, a previous frame data storage unit 40, a silence data generation unit 51, The data path switching units 52 and 53 and the reproducing unit 60 are included.

  An example of the configuration of the bitstream interpretation unit 10 with a correction function is shown in FIG. The bitstream interpretation unit 10 with a correction function is a component that temporarily inputs and holds a bitstream from an external content distribution apparatus in units of frames, and includes a bitstream interpretation unit 11, a content type determination unit 12, And a frequency domain data silencer 13. The bitstream interpretation unit 10 with a correction function has functions as a “data holding unit” and a “data input unit”.

  It should be noted that each component of the acoustic signal reproduction device 100 can be configured by dedicated hardware including a logic circuit, or hardware of a microprocessor or DSP (Digital Signal Processor) and a program for controlling the hardware. It can also be realized by a combination.

  The content type determination unit 12 has a function of determining the type of content related to the input bitstream SG1. Specifically, by examining the contents of the header of the frame constituting the input bitstream SG1, whether the content type is a bilingual sound indicating that the content type is an acoustic content including two kinds of language sounds or two countries It is determined whether the sound content is monaural sound indicating that the sound content is in a monaural format or stereo sound indicating that the sound content is in a stereo format, and the determination result is a bit as a content type signal SG11 This is given to the stream interpretation unit 11. Each of these acoustic contents is an example, and other acoustic contents may be used. The content may be digital television broadcast data.

  The acoustic content is an example of “acoustic data”. Here, the acoustic content widely includes sound-related data such as sound data, sound data, and music data.

  Here, an example of a frame constituting the input bit stream SG1 is shown in FIG. The frame 500 includes a header area 510, a data area 520, and a trailer area 530. The header area 510 includes monaural information indicating monophonic sound, stereo information indicating stereophonic sound, bilingual information indicating bilingual sound, channel information such as the number of channels, and data area 520. Data length information indicating the length of the data. The data area 520 includes channel IDs 521 (521a, 521b,...) For identifying the channels and acoustic content data 522 (522a, 522b,...) Corresponding to the channel IDs 521 for each channel. In FIG. 5, the number of channels is two, but this is not a limitation. The trailer area 530 has information indicating the end of the frame.

  For example, when the input bitstream SG1 is bilingual sound of Japanese and English, the channel ID 521a is an ID indicating Japanese, the sound content data 522a is Japanese sound data, and the channel ID 521b is English indicating an ID. The audio content data 522b stores English audio data.

  The bit stream interpretation unit 11 sequentially interprets the contents of the input bit stream SG1, separates the acoustic signal for each channel, decodes Huffman-encoded data, and checks for errors. The result of this processing is input to the frequency domain data silencer 13 as interpreted frequency domain data SG13. The bit stream interpretation unit 11 has a function as an “error determination unit”.

  In addition, when detecting an error related to the input bitstream SG1, the bitstream interpretation unit 11 outputs the bitstream error information SG12 to the frequency domain data silencer 13.

  When the bit stream interpretation unit 11 detects an error related to the input bit stream SG1 when the content type of the input bit stream SG1 is other than bilingual sound, the bit stream interpretation unit 11 simultaneously outputs the time domain correction instruction signal SG7.

  The output of SG12 may be omitted when the content type of the input bitstream SG1 is other than bilingual sound.

  Note that the input bit stream SG1 is a frequency domain acoustic signal, and information is converted from the time domain to the frequency domain by Fourier transform when compression encoded.

  The frequency domain data silencer 13 normally outputs the post-interpretation frequency domain data SG13 input from the bitstream interpretation unit 11 as corrected frequency domain data SG2, but recognizes the occurrence of an error by the bitstream error information SG12. In this case, the corrected frequency domain data SG2 is replaced with silence data for each frame and output. That is, data having a value of 0 for each frequency is output as silence data. Thereby, generation | occurrence | production of unusual noise can be prevented. The frequency domain data silencer 13 functions as a “silence data replacement unit”.

  In addition, when the input bit stream SG1 is composed of a plurality of channels of acoustic signals, the frequency domain data silencer 13 performs processing for each channel, and converts the silence data only to the channel in which an error has occurred. Perform replacement. However, when the content type of the input bitstream SG1 is other than bilingual sound, the silence processing is performed by another method using the time domain correction instruction signal SG7, and therefore the data in the frequency domain data silencer 13 is used. Replacement of is omitted.

  The frequency domain-time domain transformation unit 20 is an element that performs transformation from the frequency domain to the time domain on the input corrected frequency domain data SG2, and performs, for example, IMDCT (Inverse Corrected Discrete Cosine Transform) processing. That is, the input frequency domain acoustic signal is information corresponding to the frequency spectrum distribution, and this is converted into the original time-series acoustic signal using IMDCT processing which is a kind of inverse Fourier transform. The frequency domain-time domain converter 20 has a function as a “domain converter”.

FIG. 4 is a time chart showing an example of the configuration of an acoustic signal handled by the acoustic signal reproduction device 100.
As shown in FIG. 4, an actual time-series acoustic signal is composed of a number of frames that appear continuously in time-series. Also, adjacent frames appear in a state where they overlap each other by a maximum of half. Each frame is composed of data of 2048 samples, and appears in a state where the data of 1024 samples in the latter half of the previous frame and the data of 1024 samples in the first half of the subsequent frame overlap.

  In order to restore the acoustic signal before compression encoding, it is necessary to perform arithmetic processing on the data of adjacent frames in the time domain windowing unit 30, so the frequency domain-time domain conversion unit 20 performs the IMDCT processing. The conversion result is simultaneously output as current frame time domain data SG3 and next frame time domain data SG4.

  The current frame time domain data SG3 normally passes through the data path switch 52 and is input to the time domain windowing unit 30 as corrected current frame time domain data SG31.

  Further, the time region data SG4 for the next frame usually passes through the data path switch 53, and is input to the previous frame data storage unit 40 and stored as corrected time region data SG41 for the next frame. Is read from the previous frame data storage unit 40 and input to the time domain windowing unit 30 as previous frame time domain data SG5.

  The time domain windowing unit 30 adds the corrected current frame time domain data SG31 and the previous frame time domain data SG5, and outputs the result as output acoustic data SG6. The time domain windowing unit 30 has a function as a “reproduction data generation unit”.

  The silence data generation unit 51 generates time domain silence data SG8. The time domain silence data SG8 is input to the inputs of the data path switchers 52 and 53, respectively. This time-domain silence data SG8 is data having a value of 0, and is continuously output over a time corresponding to one frame.

  The data path switchers 52 and 53 switch the switch state based on the time domain correction instruction signal SG7 output from the bitstream interpretation unit with correction function 10. Specifically, for example, when the time domain correction instruction signal SG7 is acquired by not sending the time domain correction instruction signal SG7 from the bitstream interpretation unit 10 when no error has occurred, an error occurs. If it does not occur and is not acquired, it can be recognized that no error has occurred. The data path switchers 52 and 53 have a function as a “silent data replacement unit”.

  When no error has occurred in the input bitstream SG1 or the corrected frequency domain data SG2, the data path switcher 52 corrects the current frame time domain data SG3 based on the time domain correction instruction signal SG7. The frame time domain data SG31 is selected, and the data path switch 53 selects the next frame time domain data SG4 as the corrected next frame time domain data SG41.

  In addition, when the content type of the input bit stream SG1 is other than bilingual sound, if an error related to the input bit stream SG1 or an error related to the frequency domain data SG13 after interpretation is detected, the time domain correction instruction signal SG7 is displayed. Based on this, the data path switch 52 selects the time domain silence data SG8 as the corrected current frame time domain data SG31, and the data path switch 53 selects the time domain silence data SG8 as the corrected next frame time domain data. Select as SG41.

  Therefore, in the audio signal reproduction device 100, when the content type of the input bit stream SG1 is other than bilingual sound, and the error related to the input bit stream SG1 is detected, the time domain windowing unit 30 performs the correction. Since the silence data input as the current frame time domain data SG31 and the silence data input as the previous frame time domain data SG5 are added and the result is output as the output audio data SG6, the output audio is temporarily It becomes silent. In other words, a temporary silence occurs due to the occurrence of an error.

  When no error has occurred in the input bitstream SG1 or the content type of the input bitstream SG1 is bilingual sound, the time domain windowing unit 30 uses the corrected frequency domain data SG2 as a frequency. Based on the result converted into the time domain by the area-time domain conversion unit 20, the result of the processing necessary for reproducing the acoustic signal can be output as the output acoustic data SG6.

  However, even if the content type of the input bitstream SG1 is bilingual sound, if an error occurs in the input bitstream SG1, the internal processing of the frequency domain data silencer 13 For a channel in which an error has occurred, the corrected frequency domain data SG2 is replaced with frequency domain silence data. Therefore, only the sound signal of the channel in which no error has occurred is reproduced and appears as output sound data SG6. In this case, the sound of the channel in which the abnormal sound is generated due to the occurrence of the error is temporarily controlled to be silent.

  The reproducing unit 60 reproduces the output acoustic data SG6 as an acoustic signal.

  Next, an example of the operation of the acoustic signal reproduction device 100 will be described. FIG. 3 is a flowchart showing an example of main operations of the acoustic signal reproduction device 100.

  In step S11, the content type determination unit 12 examines the content of the input bitstream SG1 and determines the content type. If it is recognized that the content type is bilingual (broadcast) audio content, the process proceeds from step S11 to step S21, and content other than the bilingual broadcast audio content (for example, mono broadcast audio content, stereo) If the broadcast audio content or the like is recognized, the process proceeds from step S11 to step S12.

  In step S12, the bit stream interpretation unit 11 interprets the contents of the input bit stream SG1. When interpreting the contents of the input bitstream SG1, for example, CRC (Cyclic Redundancy Check) is checked, and the presence or absence of an error included in the input bitstream SG1 itself (or whether the amount of error occurrence is equal to or greater than a predetermined threshold value). Or not).

  In step S13, the bit stream interpretation unit 11 checks the presence or absence of an error using the processing result in step S12. If there is an error, the process proceeds from step S13 to step S18, and if there is no error, the process proceeds to step S14.

  In step S14, the bitstream interpretation unit 11 outputs post-interpretation frequency domain data SG13. The interpreted frequency domain data SG13 is input to the frequency domain data silencer 13 and output as corrected frequency domain data SG2.

  In step S15, the frequency domain-time domain conversion unit 20 converts the corrected frequency domain data SG2 into the time domain, and generates current frame time domain data SG3 and next frame time domain data SG4 for each frame.

  In step S16, the time domain windowing unit 30 adds the corrected current frame time domain data SG31 and the previous frame time domain data SG5, and outputs the result as output acoustic data SG6.

  In step S17, the output acoustic data SG6 is reproduced as an acoustic signal.

  In step S18, the time domain correction instruction signal SG7 is output only when, for example, an error is detected as a result of interpretation by the bitstream interpretation unit 11. Based on the time domain correction instruction signal SG7, the data path switchers 52 and 53 output silence data for the corresponding frame period. That is, when the time domain correction instruction signal SG7 is output, the data path switch 52 selects the time domain silence data SG8 in place of the current frame time domain data SG3 and uses it as corrected current frame time domain data SG31. Then, the data path switch 53 selects the time domain silence data SG8 instead of the next frame time domain data SG4 and outputs it as corrected next frame time domain data SG41.

  When the time domain correction instruction signal SG7 does not appear, the data path switch 52 selects the current frame time domain data SG3 and outputs it as corrected current frame time domain data SG31, and the data path switch 53 The frame time domain data SG4 is selected and output as corrected next frame time domain data SG41.

  However, when the content type is bilingual audio content, the time domain correction instruction signal SG7 is not output, so the data path switch 52 does not fail even when an error occurs in the bitstream. The current frame time domain data SG3 is selected, and the data path switch 53 selects the next frame time domain data SG4.

  If Step S18 is executed, the process of Step S15 is skipped and the process proceeds to the next Step S16. In this case, since the time domain silence data SG8 generated by the silence data generation unit 51 is used, the current frame time domain data SG3 and the next frame time domain data SG4 are unnecessary, and therefore the frequency domain-time domain conversion unit 20 Can also temporarily stop the conversion process.

  On the other hand, if it is determined in step S11 that the content type is bilingual audio content, processing is performed for each channel of the input bitstream SG1.

  In step S21, the bit stream interpretation unit 11 interprets the contents of the bit stream for the L channel (for example, the main acoustic channel or the secondary acoustic channel) included in the input bit stream SG1, and decodes the acoustic signal.

  In step S22, the bitstream interpretation unit 11 determines whether an error relating to the data component of the L channel acoustic signal (for example, the acoustic content data 522a in FIG. 5) is detected in step S21. The process proceeds to step S24, and if there is no error, the process proceeds to step S23.

  In step S23, the frequency domain data silencer 13 inputs the post-interpretation frequency domain data SG13 output from the bitstream interpretation unit 11 for the data component of the L-channel acoustic signal without error, and this is corrected as it is. Output as data SG2.

  In step S24, the frequency domain data silencer 13 inputs the post-interpretation frequency domain data SG13 output from the bitstream interpretation unit 11 for the data component of the L channel acoustic signal having an error, and the frequency domain is prepared in advance. Replaced with silence data (data with a value of 0 for each frequency), and output as corrected frequency domain data SG2.

  In step S25, the bit stream interpretation unit 11 interprets the contents of the bit stream for the R channel (for example, the secondary acoustic channel or the main acoustic channel) included in the input bit stream SG1, and decodes the acoustic signal.

  In step S26, the bitstream interpretation unit 11 determines in step S25 whether an error relating to the data component of the R channel audio signal (for example, the audio content data 522b in FIG. 5) has been detected. Proceeds to step S28, and if there is no error, proceeds to step S27.

  In step S27, the frequency domain data silencer 13 inputs the post-interpretation frequency domain data SG13 output from the bitstream interpretation unit 11 for the data component of the R-channel acoustic signal without error, and the corrected frequency domain is input as it is. Output as data SG2.

  In step S28, the frequency domain data silencer 13 inputs the post-interpretation frequency domain data SG13 output from the bitstream interpretation unit 11 for the data component of the R channel acoustic signal having an error, and the frequency domain is prepared in advance. It is replaced with silence data and output as corrected frequency domain data SG2.

  Even in the case of processing the input bitstream SG1 which is the bilingual sound content, the process proceeds to step S15 after executing step S27 or S28, so that the corrected frequency domain data output by the bitstream interpretation unit with correction function 10 is output. SG2 is converted into time domain data by the frequency domain-time domain conversion unit 20 for each channel, and time domain data SG3 for the current frame and time domain data SG4 for the next frame are generated.

  When the input content is bilingual audio content, the data path switchers 52 and 53 do not select the time domain silence data SG8, so that the current frame time domain data SG3 and the next frame time domain data SG4 are used. The time domain windowing unit 30 generates output acoustic data SG6. However, if an error has occurred in the input bitstream SG1, the sound of the channel with the error is replaced with silence data within the frequency domain data silencer 13, so that the output sound data SG6 is in a silent state. A signal is output.

  Also, if the input content is bilingual audio content, for example, even if there is no error in the main audio channel and an error has occurred only in the secondary audio channel, it is controlled independently for each channel. For the main sound channel, the sound signal is reproduced as output sound data SG6 as it is, and only the sub sound channel is replaced with the silent state.

  Therefore, for viewers who often view only channels with relatively few errors, the target channel can be viewed even when one channel is silent. The frequency of occurrence is reduced.

  Although the case where bilingual sound is used as sound content using a plurality of channels has been described here, sound content in two or more languages may be used. Further, the present invention can be applied to audio content using a plurality of channels, not audio content including two or more foreign languages.

  According to such an audio signal reproduction device 100, the frequency domain audio signal that has been decoded by the bitstream interpretation unit 11 or the time domain audio after being converted by the frequency domain-time domain conversion unit 20. The signal can be replaced with silence data for each frame, and the output can be obtained simply by preparing a certain silence data regardless of the difference in the channel configuration or the sampling rate of the acoustic signal input as the input bit stream SG1. It can be controlled to silence. Further, a large-capacity memory for holding a large amount of encoded data and a complicated charge circuit for generating encoded data are unnecessary. Note that the silence control may be omitted for errors that can be corrected or errors that cannot be recognized by the viewer.

  As described above, the present invention is useful as an audio signal reproducing device that inputs and reproduces a bit stream of an audio signal that has been compression-encoded in accordance with a standard such as AAC. For example, a television receiver that receives a digital television broadcast It is useful for a mobile phone terminal, a digital audio device, etc. having a function of receiving digital broadcasting.

It is a block diagram which shows an example of a structure of the acoustic signal reproducing | regenerating apparatus in embodiment of this invention. It is a block diagram which shows an example of a structure of the bit stream interpretation part with a correction function in embodiment of this invention. It is a flowchart which shows an example of main operation | movement in the acoustic signal reproducing | regenerating apparatus in embodiment of this invention. It is a time chart which shows the structural example of the acoustic signal which the acoustic signal reproduction apparatus in embodiment of this invention handles. It is a figure which shows an example of the flame | frame which the acoustic signal reproducing | regenerating apparatus in embodiment of this invention processes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Sound signal reproduction apparatus 10 Bit stream interpretation part with correction function 11 Bit stream interpretation part 12 Content type determination part 13 Frequency domain data silence part 20 Frequency domain-time domain conversion part 30 Time domain windowing part 40 Previous frame data storage part 51 Silent Data Generation Unit 52, 53 Data Path Switcher 60 Playback Unit 500 Frame 510 Header Area 520 Data Area 521 Channel ID
522 Sound content data 530 Trailer region SG1 Input bit stream SG2 Corrected frequency region data SG3 Current frame time region data SG4 Next frame time region data SG5 Previous frame time region data SG6 Output sound data SG7 Time region correction instruction signal SG8 Time region Silence data SG11 Content type signal SG12 Bit stream error information SG13 Interpreted frequency domain data SG31 Corrected current frame time domain data SG41 Corrected next frame time domain data

Claims (7)

A data holding unit for holding content data having channel information on a plurality of channels and sound data corresponding to each channel in units of frames;
An error determination unit that determines whether there is an error in the acoustic data of each channel in the frame;
When it is determined that there is the error, a silence data replacement unit that replaces acoustic data of a channel determined to have the error in the frame with predetermined silence data;
A reproduction data generation unit that generates acoustic reproduction data for reproduction based on the acoustic data and the silence data of each channel in mutually adjacent frames;
A sound signal reproduction device comprising: a reproduction unit that reproduces the sound reproduction data. The acoustic signal reproducing apparatus according to claim 1, further comprising:
An acoustic signal reproduction device having a data input unit for inputting the content data from an external content distribution device. The acoustic signal reproduction device according to claim 1, further comprising:
It has a domain conversion unit that converts frequency domain data to time domain data,
The data holding unit holds acoustic data in the frequency domain,
The error determination unit determines whether there is an error in the frequency domain acoustic data,
The reproduction data generation unit is an acoustic signal generation device that generates the acoustic reproduction data based on acoustic data and silence data in a time domain of each channel in adjacent frames after conversion by the region conversion unit. The acoustic signal reproduction device according to claim 3, further comprising:
A content type determination unit for determining the type of the acoustic data;
The region conversion unit converts the acoustic data held in the data holding unit into time domain data,
The silence data replacement unit, when the content type determination unit determines that the acoustic data is not data including audio data of a plurality of languages, the time domain of the channel determined to have the error in the frame An acoustic signal reproduction device that replaces acoustic data with predetermined silence data in the time domain. The acoustic signal reproduction device according to claim 3, further comprising:
A content type determination unit for determining the type of the acoustic data;
The silence data replacement unit, when the content type determination unit determines that the acoustic data is data including audio data of a plurality of languages, a frequency domain of a channel determined to have the error in the frame Replace acoustic data with predetermined silence data in the frequency domain,
The said area | region conversion part is an acoustic signal reproduction | regeneration apparatus which converts the acoustic data and silence data of a frequency domain into data of a time domain. The acoustic signal reproduction device according to claim 1, wherein
The content data is an audio signal reproduction device which is streaming data or digital television broadcast data. In an acoustic signal reproduction device,
Holding content data having channel information on a plurality of channels and acoustic data corresponding to each channel in units of frames;
Determining whether there is an error in the acoustic data of each channel in the frame;
If it is determined that there is an error, replacing acoustic data of a channel determined to have the error in the frame with predetermined silence data; and
Generating sound reproduction data for reproduction based on the sound data and silence data of each channel in mutually adjacent frames;
A method of reproducing the sound reproduction data.

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