JP2005266571A - Method and device for variable-speed reproduction, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize adverse influence on an audio signal without changing the interval while simplifying constitution when the audio signal is reproduced at a variable speed. <P>SOLUTION: At a step S1, the audio signal is reproduced at a variable speed different from that in recording and at a step S2, a division period Ta of OLA (overlap addition) processing, a length Tb of an overlap part, and a repetition period Tc of the overlap part are determined according to whether the reproduced audio signal is a speech or music. At a step S3, the reproduced audio signal is divided into blocks of a time Ta and at a step S4, the tail part of one block and the head part of a next block are connected through cross-fading processing while overlapping each other for a time Tb. When the reproduced audio signal is a speech, the time Tc is ≥0.05 second and the time Tb is 0.01 to 0.05 second, but when music, the time Ta is <0.05 second. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable speed reproduction method and apparatus, and a program that perform reproduction at a reproduction speed different from a standard speed (recording speed) without changing the pitch of an audio signal such as voice or musical sound.

  Technology that converts the playback speed without changing the pitch of the audio signal when the playback speed when playing back from a recording medium such as an optical disk, magnetic disk, or magnetic tape is different from the (standard) speed during recording. Are known. This is because, for example, when a television broadcast program or the like is recorded on a recording medium such as a hard disk and news or the like is to be played back quickly, it is difficult to hear when the pitch changes, so that the pitch does not change even when played back quickly. For this purpose, a technique that does not change the pitch even when the variable speed reproduction is used is used.

  As an example of a technique for changing the playback speed without changing the pitch, time-domain digital audio data obtained by variable speed playback is once converted into frequency-domain data and returned to the pitch at the time of recording on the frequency axis. There is a technique for performing inverse conversion to time domain data again after performing such processing. In such a technique involving processing in the frequency domain, DCT (discrete cosine transform), MDCT (improved DCT), DFT (discrete Fourier transform), etc. for transforming between time domain and frequency domain and inverse transform As a simpler technique, as shown in Non-Patent Document 1 and Patent Document 1, data processing in the time domain is known, because the above-described calculation processing is required, the processing becomes complicated, and the amount of calculation increases. ing. This is because the audio signal obtained by playing back from the recording medium at different playback speeds is divided into blocks at regular intervals, and the end of one block overlaps the end of the next block. The connection is performed smoothly by performing the cross fading process at each overlap portion (overlap addition: OLA).

  That is, the original (recording) audio signal as shown in FIG. 4A is divided into blocks for each first time Ta on the recording time axis, as shown in FIG. , The ends of the blocks A, B, C,... Overlap each other for a second time Tb on the recording time axis, and are connected while performing crossfade processing. At this time, the portion r of the time Tb on the end side of the block A and the portion f of the time Tb on the front end side of the next block B overlap (overlap), and the end portion r of the block A fades out (gradually). The block A and the block B are joined so that the leading end portion f of the next block B fades in (increases gradually). At this time, the overlap portion is repeatedly obtained with the third time Tc (Tc = Ta−Tb) as a repetition period, and the recording time Ta is compressed to the time Tc. As a result, playback is performed at a playback speed that is Ta / Tc times faster than that during recording without changing the pitch.

Kaname Ogawa, “Audio Digital Signal Processing Recipe with Digital Filter Software, PART3 Special Signal Processing, OLA”, C MAGAZINE, Softbank Publishing Co., Ltd., March 2002, p. 35-36 JP-A-8-287612

  By the way, as described above, the technique in which the reproduction signal is divided into blocks in the time domain and the ends are overlapped and connected while cross-fading has the following problems.

  In other words, the audio signal waveform at the time of original recording overlaps the above-described overlap portion, resulting in distortion in audibility. In order to maintain a good overall audibility, it is necessary to adjust the division period and the size of the overlap part. However, when the overlap part is repeated, a sense of pitch occurs, and the original recording audio This may cause an unpleasant pitch difference with respect to the signal.

  In addition, the size of the overlap part is inevitably determined from the size of the division period depending on the fixed time reduction rate, but if the division period is increased and the overlap part becomes large as a result, consonant sounds are used in human speech etc. Or the sound generation start timing becomes inconsistent, and good sound reproduction cannot be performed.

  The present invention has been proposed in view of such a conventional situation, and does not change the pitch even when reproduced at a reproduction speed different from that at the time of recording, and is simple as in the so-called overlap addition (OLA). It is an object of the present invention to provide a variable speed reproduction method and apparatus, and a program that can minimize adverse effects on voice and music while using various technologies.

  In order to solve the above-described problem, the present invention reproduces an audio signal recorded on a recording medium at a reproduction speed different from that at the time of recording, and the reproduced audio signal is a first divided period on the recording time axis. Are divided into blocks of time Ta, and the end portion of one divided block and the tip portion of the next block overlap at the second time Tb on the recording time axis, and crossfade processing is performed at each overlap portion. When the audio signal is an audio signal, the third time Tc (Tc = Ta−Tb), which is the repetition period of the overlap portion, is set to 0.05 seconds or more, and the overlap is performed. When the second time Tb of the portion is 0.01 seconds to 0.05 seconds and the audio signal is a music signal, the first time Ta that is the division period is 0.05 seconds or less. And wherein the Rukoto.

  Here, when the reproduced audio signal includes an audio signal and a music signal, or when it is not possible to distinguish between the audio signal and the music signal, the third time Tc (Tc = Ta−Tb) which is the repetition period of the overlapped portion. ) Is set to 0.025 seconds or more, and the second time Tb of the overlap portion is set to 0.005 seconds to 0.025 seconds.

  Further, it is preferable to determine whether the reproduced audio signal is an audio signal or a music signal, and to switch each time Ta to Tc according to the determined type of the audio signal.

  When the playback speed is 1.3 times the recording speed and the audio signal is an audio signal, the third time Tc, which is the repetition period of the overlap portion, is set to 0.111 seconds, and the overlap portion In the case where the second time Tb is 0.033 seconds, and the audio signal is a music signal, the first time Ta that is a division cycle is 0.024 seconds, and the second time Tb of the overlap portion is 0.0053. Preferably it is seconds.

  According to the present invention, when the audio signal to be reproduced with variable speed is an audio signal, the repetition period (third time) Tc of the overlap portion is set to 0.05 seconds or more, thereby repeating the overlap portion. Since the fundamental frequency component is 20 Hz or less and is out of the range of 85 Hz to 8 kHz, which is the normal human voice signal band, BGM (background music) that has little adverse effect on the voice and does not require much emphasis on the low frequency range. ) And the overlap portion time (second time) Tb is set to 0.01 seconds to 0.05 seconds, so that the attenuation curve when the overlap portion is crossfade is sharp. While suppressing the waveform distortion due to becoming, it is possible to reduce the influence of the time relationship of the previous and subsequent blocks in the overlapped portion is reversedFurther, when the audio signal to be played back at a variable speed is a music signal, the first time Ta, which is the division cycle, is set to 0.05 seconds or less, so that the tempo of the music is kept good. Furthermore, since each appropriate time Ta to Tc is set according to the attribute indicating the type or genre, such as whether the audio signal to be played with a variable speed is a sound signal or a music signal, the characteristics of each audio signal are effectively used. The maintained variable speed reproduction can be realized.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

    FIG. 1 is a block diagram schematically showing a variable speed playback apparatus used in an embodiment of the present invention. In FIG. 1, a hard disk device 11 as a recording medium is connected to a bus 13 via an interface (I / F) circuit 12. The bus 13 includes, for example, an MPEG encoding / decoding circuit 14 for compressing / encoding / decoding a video signal, an audio processing circuit 21 for performing compressing / encoding / decoding of an audio signal, the above-described OLA (overlap addition), and the like. For example, an IO (input / output) processor 22 is connected to the IO processor 22, and a buffer memory 23 is connected to the IO processor 22. A PCM (pulse code modulation) signal and an SPDIF (Sony Philips digital interface) signal from the audio processing circuit 21 are sent to the audio mixer 24, and the PCM signal from the audio mixer 24 is converted into an analog signal by the D / A converter 25. The SPDIF signal from the audio mixer 24 is sent to the terminal 27.

  FIG. 2 is a block diagram showing the audio signal system of the variable speed reproduction apparatus of FIG. 1 in more detail. However, in the case of an apparatus for recording and reproducing only an audio signal, only the configuration of FIG. FIG. 2 is a block diagram showing an example of a variable speed reproduction apparatus suitable for variable speed reproduction of an audio signal.

  In FIG. 2, a hard disk device 11 as a recording medium is connected to an interface (I / F) circuit 12, and the interface circuit 12 is connected to an error correction encoding / decoding circuit 31 and a system controller 41. The error correction encoding / decoding circuit 31 is connected to the audio compression encoding / decoding circuit 32, and the digital audio signal from the audio compression encoding / decoding circuit 32 is sent to the D / A converter 35 via the memory controller 33. And converted into an analog signal and taken out from the output terminal 36. A buffer memory 34 is connected to the memory controller 33. An analog audio signal from the input terminal 38 is converted into a digital signal by the A / D converter 37 and sent to the audio compression encoding / decoding circuit 32.

  The system controller 41 shown in FIG. 2 is configured with a microcomputer and manages the overall operation. The system controller 41 is given a key input signal from the key group 42. The key group 42 includes a power key, an eject key, a reproduction key, a pause key, a stop key, a recording key, a fast forward reproduction key, a fast reverse reproduction key, and the like.

  Further, in the case of a variable speed playback apparatus with only audio signals, it is preferable to connect a display 43 to the system controller 41. The display 43 includes time information such as the total performance time of the mounted small optical disc, the elapsed time of the song being played, the remaining performance time of the song being played back, the remaining performance time of the entire song, and the time of the song being played The track number is displayed. In the case of a disc on which a disc name or track name is recorded, the disc name or track name is displayed. Further, if the recording date / time of the song or disc is recorded, the recording date / time is displayed.

  As shown in FIG. 1, in the case of a variable speed playback device that records and plays back a video signal, a video display device (not shown) for displaying the video signal is connected to the video display device. Information such as the performance time may be displayed. When the configuration of FIG. 2 is used as the audio signal system of the variable speed playback apparatus of FIG. 1, the display 43 of FIG. 2 is not necessary.

  Further, the system controller 41 of FIG. 2 detects EPG (electronic program guide) genre information and the like as attribute information indicating the type (genre) such as whether the reproduced audio signal is a sound signal or a music signal. A detection circuit 45 is connected.

  At the time of recording an audio signal, the analog audio signal supplied to the input terminal 38 is converted into a digital signal by the A / D converter 37, sent to the audio compression encoding / decoding circuit 32, and subjected to audio compression encoding processing. It is sent to the error correction encoding / decoding circuit 31. The error correction encoding / decoding circuit 31 adds a parity for error correction and records it on the hard disk device 11 via the interface circuit 12 for hard disk. In the case of data that has been previously compression-encoded as in digital television broadcasting, it is recorded in the hard disk device 11 via the interface circuit 12 as it is or after being subjected to only necessary signal processing.

  When an audio signal is played back, the reverse processing to that at the time of recording is performed. In particular, a case where playback is performed at a playback speed different from that at the time of recording, for example, a playback speed higher than that at the time of recording will be described below.

  At the time of variable speed reproduction, for example, at the time of high-speed reproduction such as when the recorded television broadcast program is quickly reproduced, the system controller 41 in FIG. 2 is faster than the speed (recording speed) during normal reproduction from the hard disk device 11. Alternatively, data is read at a high rate, error correction processing is performed by the error correction encoding / decoding circuit 31, and control is performed so that the audio compression encoding / decoding circuit 32 performs decompression decoding processing of the compression-coded audio signal. The audio signal from the audio compression encoding / decoding circuit 32 is a time-domain signal and is temporarily stored in the buffer memory 34 via the memory controller 33. When the system controller 41 reads the audio signal from the buffer memory 34, the end portion r of one block and the end portion f of the next block are temporally separated as shown in FIG. Reading so as to overlap (overlapping), the end portion r of one block fades out (gradually decays), and the leading end f of the next block fades in (gradually increases), so-called crossfade In addition, the one block and the next block are smoothly connected by adding and mixing (mixing) the one block and the next block. In FIG. 4B, for example, the end portion r of the block B is faded out, the front end portion f of the next block C is faded in and mixed, and the block B and the block C are smoothly connected.

  Here, Ta is the first time on the recording time axis as the block division period of the reproduced audio signal, and the recording time of the overlapped portion at the end of one divided block and the tip of the next block When the second time on the axis is Tb, the overlap portion is repeated with the period of the third time Tc (Tc = Ta−Tb), and the data of the first time Ta at the time of recording is the first. It is compressed and reproduced at time Tc of 3. In this case, the reproduction speed is Ta / Tc times the recording speed (standard reproduction speed).

  When the reproduced audio signal is a human sound (speech sound), the repetition frequency (1 / Tc) of the overlap portion is out of the generally effective voice band (for example, 85 Hz to 8 kHz). Considering that it is desirable to reduce the influence of overtones, 1 / Tc is set to 20 Hz or less, that is, the third time Tc is set to 0.05 seconds or more. In this case, the fundamental frequency component due to repetition of the overlap portion is 20 Hz or less, and is lower than the lower limit of the voice band, for example, 85 Hz, up to about the second to third harmonics of overtones. Can be suppressed. On the other hand, if the second time Tb, which is the length of the overlap portion, is too short, the attenuation curve for crossfading becomes steep, and the influence of distorting the audio signal waveform at the block end cannot be ignored. Considering that, if it is 0.01 seconds or longer and is too long, the reversal of time caused by the sound generated at the end of the previous block being delayed from the sound generated at the end of the next block cannot be ignored for hearing. In consideration of the above, it was set to 0.05 seconds or less. In this way, by setting the second time Tb, which is the length of the overlap portion, to 0.01 seconds to 0.05 seconds, the waveform distortion at the block end is small, and the time at the overlap portion is reduced. The reversal phenomenon is also suppressed to the extent that there is no problem with hearing. In the case of this audio signal, the first time Ta, which is the block division period, is 0.06 seconds or more from Ta = Tc + Tb.

  On the other hand, when the audio signal to be reproduced is mainly music (music), for example, when a music program is played at a high speed, the tempo of the music is set for each time Ta to Tc in the case of the audio signal. The feeling is impaired. That is, in the case of music, it is important that the lengths of the notes are accurately reproduced. If the division period Ta is 0.06 seconds or more as in the case of the audio signal, the length of the division block is reduced. Since it approaches the time of the shortest note or becomes longer than the shortest note, if the overlap is added, the length of the note becomes inaccurate, and the sense of tempo or rhythm is disturbed. Considering this point, the block division period (first time) Ta in the case of a music signal is set to 0.05 seconds or less. The overlap portion length (second time) Tb depends on how many times the playback speed is. For example, in the case of 1.3 times speed playback, the second time Tb is 0.12 seconds or less. Become. As described above, when the first time Ta and the second time Tb are shortened, the influence of the repetition frequency of the overlap portion on the low frequency band and the middle frequency band, and the waveform distortion at the overlap portion are high. Although the influence on the sound quality including the frequency band cannot be ignored, if the music signal is processed by the OLA (overlap addition) as described above, the influence on the sound quality is unavoidable. In consideration of the point that it is most important that the tempo or rhythm of the song is maintained in the case of reproduction, the first time Ta is set to 0.05 seconds or less as described above. .

  In addition, when the voice and music are both mixed and important, such as music variety programs and musicals, or when it is difficult to distinguish between voice and music, each of the times Ta to Tc is as described above. It is preferable to set an intermediate value between audio and music. Considering this point, when the reproduced audio signal includes an audio signal and a music signal, or when it is not possible to distinguish between the audio signal and the music signal, the third time Tc that is the repetition period of the overlap portion is set to 0.025. The second time Tb, which is the length of the overlap portion, is set to 0.005 seconds to 0.025 seconds.

  In this way, considering that the appropriate value of each time Ta to Tc when the audio signal is subjected to OLA (overlap addition) processing differs depending on the type or genre of the program that is reproduced at high speed by fast-viewing reproduction, etc. It is preferable to switch and control each time Ta to Tc depending on the type or genre. Specifically, the type and genre of a program to be played back by a human being is judged, and the key group 42 in FIG. 2 is manually operated to cause the system controller 41 to switch and control the values of each time Ta to Tc. Is mentioned. If a so-called EPG (electronic program guide) of a television broadcast program can be obtained, attribute information indicating the type and genre of the program in the EPG information is extracted by the EPG detection circuit 45 of FIG. May be controlled to switch the values of the respective times Ta to Tc.

  Next, when the embodiment of the present invention is applied to a so-called hard disk recorder or the like of a video signal, it can be used to quickly reproduce a television broadcast program that has been collected, and the reproduction speed in this case is about double. However, as a playback speed that can further enjoy the contents of the program to some extent, about 1.3 to 1.5 times speed can be considered. As a specific example, examples of best tuning times Ta to Tc when the playback speed is 1.3 times the recording speed (standard playback speed) will be given below.

  When the audio signal reproduced at the standard 1.3 times speed is an audio signal, the third time Tc that is the repetition period of the overlap portion is set to 0.111 seconds, and the second time that is the length of the overlap portion. Tb is set to 0.033 seconds. At this time, the fundamental frequency component due to the repetition of the overlap portion is about 9 Hz, which is sufficiently lower than the lowest frequency range of 85 Hz to 8 kHz, which is the human voice band, and therefore includes harmonics of several orders. There is little adverse effect, and there is little influence on BGM (background music) that does not need to emphasize the low range too much. In addition, since the length (second time) Tb of the overlap portion is 0.033 seconds, the overlap portion is suppressed while suppressing waveform distortion due to a steep attenuation curve when the overlap portion is crossfade. Can reduce the influence of the time relationship between the previous and next blocks being reversed.

  When the audio signal reproduced at the standard 1.3 times speed is a music signal, the first time Ta that is the block division period is set to 0.024 seconds, and the second time Tb that is the length of the overlap portion. Is 0.0053 seconds. Here, when assuming a tune of about 250 (MM = 250) with one quarter note as a song with a very fast tempo, the length of the quarter note is 0.24 seconds, Since the sixth note is 0.06 seconds, if the block division period is 0.024 seconds, the quarter note is divided into about 10 blocks, and even the 16th note is divided into about 2 to 3 blocks. Thus, the tempo or rhythmic disturbance due to OLA (overlap addition) is hardly felt.

  Therefore, the system controller 41 in FIG. 2 outputs the audio signal in accordance with OLA (overlap addition) in response to a human operating the key group 42 by determining the genre or according to the genre information from the EPG detection circuit 45. ) When the time Ta to Tc for processing is controlled to be switched, and the program to be played back at high speed is a genre in which audio signals such as news and dramas are important, the repetition period of the overlap portion The time Tc of 3 is switched to 0.111 seconds and the second time Tb, which is the length of the overlap portion, is controlled to be switched to 0.033 seconds. In the case of a different genre, the first time Ta, which is the division cycle, is switched to 0.024 seconds, and the second time Tb, which is the length of the overlap portion, is switched to 0.0053 seconds. That.

  As a result, an optimal OLA (overlap addition) process is performed on the audio signal of the program to be played back at high speed, and a good audio signal can be heard without changing the pitch despite the simple configuration.

  Next, FIG. 3 is a flowchart for explaining the operation of the variable speed reproduction method according to the embodiment of the present invention. In FIG. 3, the audio signal is reproduced at a higher speed (eg, 1.3 times faster) than the standard reproduction speed (recording speed) by variable speed reproduction at step S1, for example, the above-mentioned quick-reproduction.

  In the next step S2, the respective times Ta, Tb, Tc are determined according to the type and genre of the signal reproduced at high speed, for example, depending on whether the audio signal is mainly voice or music. decide. Specifically, for example, in the case of 1.3 times quick playback, the system controller 41 in FIG. 2 sets the repetition period (third time Tc) of the overlap portion to 0.111 seconds in the case of an audio signal. The overlap portion length (second time Tb) is controlled to be switched to 0.033 seconds. In the case of a music signal, the division period (first time Ta) is set to 0.024 seconds, and the overlap portion is Is switched to 0.0053 seconds (second time Tb). In general, when the reproduced audio signal is an audio signal, the third time Tc, which is the repetition period of the overlap portion, is set to 0.05 seconds or more, and the second time Tb, which is the length of the overlap portion, is set. When the playback audio signal is a music signal, the first time Ta, which is the division period, is set to 0.05 seconds or less. When the reproduced audio signal includes a voice signal and a music signal, or when it is not possible to distinguish between the voice signal and the music signal, the third time Tc that is the repetition period of the overlap portion is set to 0.025 seconds or more, The second time Tb that is the length of the overlap portion is set to 0.005 seconds to 0.025 seconds.

  In the next step S3, the audio signal is divided into blocks for each first time Ta on the recording time axis which is a block division cycle, and in the next step S4, the end of each block is set to the second time on the recording time axis. Are overlapped only for a time Tb and connected by crossfading.

  According to the embodiment of the present invention as described above, when the audio signal to be played back at a variable speed is an audio signal, the fundamental frequency component due to the repetition of the overlap portion is sufficiently low, which is a human audio band. Since it is outside the range of 85Hz to 8kHz, there is little adverse effect on the sound, there is little effect on BGM (background music) that does not need to emphasize the low range too much, and attenuation when cross-fading the overlap part While suppressing the waveform distortion due to the steep curve, the influence of reversing the time relationship between the preceding and succeeding blocks in the overlap portion can be reduced. Further, when the audio signal to be played back at a variable speed is a music signal, the tempo of the music is kept good. Furthermore, when the audio signal to be played back at a variable speed includes a sound signal and a music signal, or when it cannot be distinguished whether it is a sound signal or a music signal, the tempo of the music is kept moderate while suppressing the influence on the sound to some extent. Playback is possible. As described above, since the appropriate times Ta to Tc are set according to the attribute indicating the type or genre such as whether the audio signal to be reproduced with a variable speed is an audio signal or a music signal, the properties of the respective audio signals are set. It is possible to realize variable speed reproduction while maintaining good conditions.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

1 is a block diagram showing a schematic configuration of a variable speed playback device according to an embodiment of the present invention. It is a block diagram which shows the structural example of the audio signal type | system | group of the variable speed reproduction apparatus in embodiment of this invention. It is a flowchart for demonstrating the speed-change reproduction | regeneration method used as embodiment of this invention. It is explanatory drawing for demonstrating the technique of OLA (overlap addition) for carrying out variable speed reproduction, without changing an audio | voice.

Explanation of symbols

11 hard disk drive, 12 interface (I / F) circuit, 14 MPEG encoding / decoding circuit, 21 audio processing circuit, 22 IO (input / output) processor, 23 buffer memory, 31 error correction encoding / decoding circuit, 32 audio compression encoding / decoding Decode circuit, 33 memory controller, 34 buffer memory, 41 system controller, 42 key group, 43 display, 45 EPG detection circuit

Claims (10)

A reproduction step of reproducing the audio signal recorded on the recording medium at a reproduction speed different from that at the time of recording;
A division step of dividing the reproduced audio signal into blocks of a first time Ta as a division period on the recording time axis;
A connecting step in which the end portion of the divided one block and the leading end portion of the next block are overlapped at a second time Tb on the recording time axis, and crossover processing is performed at each overlap portion. And
When the audio signal is an audio signal, the third time Tc (Tc = Ta−Tb), which is the repetition period of the overlap portion, is set to 0.05 seconds or more, and the second time Tb of the overlap portion is set. 0.01 seconds to 0.05 seconds,
When the audio signal is a music signal, the first time Ta, which is the division period, is set to 0.05 seconds or less. When the reproduced audio signal includes an audio signal and a music signal, or when it is not possible to distinguish between an audio signal and a music signal,
A third time Tc (Tc = Ta−Tb) that is a repetition period of the overlap portion is set to 0.025 seconds or more, and a second time Tb of the overlap portion is set to 0.005 seconds to 0.025 seconds. The variable speed reproduction method according to claim 1, wherein: A determination step of determining whether the reproduced audio signal is an audio signal or a music signal;
2. The variable speed reproduction method according to claim 1, wherein the times Ta to Tc are switched in accordance with the type of the audio signal discriminated in the discriminating step. When the playback speed is 1.3 times the recording speed,
When the audio signal is an audio signal, the third time Tc that is the repetition period of the overlap portion is set to 0.111 seconds, the second time Tb of the overlap portion is set to 0.033 seconds,
When the audio signal is a music signal, the first time Ta, which is the division period, is set to 0.024 seconds, and the second time Tb of the overlap portion is set to 0.0053 seconds. Item 4. The variable speed reproduction method according to Item 1. Reproduction means for reproducing the audio signal recorded on the recording medium at a reproduction speed different from that at the time of recording;
The reproduced audio signal is divided into blocks of the first time Ta as a division period on the recording time axis, and the end portion of the divided one block and the leading end portion of the next block are recorded on the recording time axis. And a control means for connecting by overlapping each other at a second time Tb and performing a cross-fade process at each overlapping portion,
When the audio signal is an audio signal, the control means sets a third time Tc (Tc = Ta−Tb), which is a repetition period of the overlap portion, to be 0.05 seconds or more, and sets the third time of the overlap portion. The time Tb of 2 is 0.01 seconds to 0.05 seconds, and when the audio signal is a music signal, the first time Ta that is the division period is 0.05 seconds or less. A variable speed signal reproduction device. When the reproduced audio signal includes a sound signal and a music signal, or when the control means cannot distinguish between the sound signal and the music signal, the control means performs a third time Tc (Tc = Tc = Tc = the repetition period of the overlap portion). 6. The variable speed playback apparatus according to claim 5, wherein Ta-Tb) is set to 0.025 seconds or longer, and the second time Tb of the overlap portion is set to 0.005 seconds to 0.025 seconds. The said control means discriminate | determines whether the said reproduced audio signal is an audio | voice signal or a music signal, and switches said each time Ta-Tc according to the discriminated type of the audio signal. Variable speed playback device. When the reproduction speed is 1.3 times the recording speed and the audio signal is an audio signal, the control means sets a third time Tc that is a repetition period of the overlap portion to 0.111. Second, the second time Tb of the overlap portion is 0.033 seconds, and when the audio signal is a music signal, the first time Ta as the division period is 0.024 seconds, and the overlap 6. The variable speed playback apparatus according to claim 5, wherein the second time Tb of the portion is set to 0.0053 seconds. A reproduction step of controlling reproduction of the audio signal recorded on the recording medium at a reproduction speed different from that at the time of recording;
An attribute detection step of detecting attribute information indicating the type of the reproduced audio signal;
A division step of dividing the reproduced audio signal into blocks of a first time Ta as a division period on the recording time axis;
A connecting step in which the end portion of the divided one block and the leading end portion of the next block are overlapped at a second time Tb on the recording time axis, and crossover processing is performed at each overlap portion. And
According to the detected attribute information, the variable speed reproduction method characterized by switching and controlling the first time Ta which is the division period and the second time Tb of the overlap portion. On the computer,
A procedure for controlling playback of an audio signal recorded on a recording medium at a playback speed different from that at the time of recording;
Dividing the reproduced audio signal into blocks of a first time Ta as a division period on the recording time axis;
A procedure for connecting the end portion of the divided one block and the leading end portion of the next block at a second time Tb on the recording time axis and performing cross-fade processing at each overlap portion; A program for executing
When the audio signal is an audio signal, the third time Tc (Tc = Ta−Tb), which is the repetition period of the overlap portion, is set to 0.05 seconds or more, and the second time Tb of the overlap portion is set. 0.01 seconds to 0.05 seconds,
When the audio signal is a music signal, the first time Ta as the division period is set to 0.05 seconds or less.

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