Audio processing method, audio processing apparatus, and recording reproduction apparatus capable of outputting voice having regular pitch regardless of reproduction speed

• US 6,360,198 B1
• Filed: 05/06/1999
• Issued: 03/19/2002
• Est. Priority Date: 09/12/1997
• Status: Expired due to Term

• Current Assignee: Nippon Hoso Kyokai
• Original Assignee: Nippon Hoso Kyokai
• Inventors: Takagi, Tohru, Seiyama, Nobumasa, Imai, Atsushi
• Primary Examiner(s): Dorvil, Richemond
• Application Number:
  US09/297,730
• Time in Patent Office: 1,048 Days
• Field of Search: 704/207, 704/205, 704/210, 704/216, 704/500, 704/501, 704/503, 704/504, 704/258, 704/265, 704/266, 704/268, 704/206, 704/217, 704/218
• US Class Current: 704/207
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/005 Reproducing at a different information rate from the information rate of recording for television signals H04N5/783

Abstract

A reproduction part reproduced at a changeable speed ratio r. An A/D conversion part A/D converts, based on sampling frequency f_i, an audio signal reproduced at a speed different from that upon recording. A block data division part divides audio data based on an attribute possessed by the audio data. An audio data connection part successively interpolates or thins out the divided audio data based on a ratio of 1/r. A D/A conversion part D/A converts the interpolated or thinned-out audio data based on sampling frequency f_o. If a relation of f_i/f_o=r/c is satisfied, the audio signal is outputted as a sound of high quality constantly synchronized with an image signal and having a pitch which does not change irrespective of the changeable speed ratio r at which the image signal is reproduced.

Claims

1. An audio processing method of, when reproducing, at a reproduction speed different from that at which an audio signal have been recorded in a recording medium, the audio signal on the recording medium, adjusting the pitch of the reproduced audio signal, the method comprising the steps of:

performing A/D conversion, at a sampling frequency f_i, of the audio signal that has been reproduced from the recording medium;

performing analysis processing on audio data that has been obtained by the A/D conversion according to the attribute thereof;

dividing the audio data into block units each having a prescribed time width according to data that has been obtained by the analysis processing;

performing a series of processings of performing interpolation or thinning processing on the audio data in divided block units if necessary to thereby make data length thereof I/r greater and thereby produce output audio data;

performing D/A conversion, at a sampling frequency f_o, of the thus-produced output audio data to thereby output a sound synchronized with an image; and

setting the respective sampling D/A conversion of the audio data to thereby produce an audio signal, and the changeable speed ratio r may satisfy prescribed conditions.

2. An audio processing method according to claim 1, wherein as the prescribed conditions, when the sampling frequencies f_i and f_o and the changeable speed radio r satisfy the relationship of f_i/f_o=r, there is used the sampling frequency f_i which is represented by an expression f_i=r·

f_o; and

when the sampling frequencies f_i and f_o and the changeable speed ratio r are in the relationship of f_i/f_o≠

r, there is used the sampling frequency f_i that is represented by an expression f_i=r·

f_o/c that includes a sampling frequency conversion coefficient c.

3. An audio processing method according to claim 2, when performing digital signal processing on the audio data that has been obtained by performing A/D conversion, at the sampling frequency f_i, of the audio signal that has been reproduced from the recording medium at the changeable speed ratio r, the digital signal processing comprising the steps of:

monitoring time data of the audio signal read out from the recording medium and time data of the output audio data that has been obtained through the performance of the series of processes to thereby correct time non-coincidence that occurs between the audio signal and the output audio data.

4. An audio processing apparatus for, when reproducing, at a reproduction speed different from that at which an audio signal has been recorded in a recording medium, the audio signal on the recording medium, adjusting the pitch of the reproduced audio signal, the audio processing apparatus comprising:

A/D conversion means (3) for performing A/D conversion, at a sampling frequency f₁, of the audio signal that has been reproduced from the recording medium;

analysis processing means (5) for performing analysis processing on audio data that has been obtained by the A/D conversion according to the attribute thereof;

block data division means (6) for dividing the audio data into block units each having a prescribed time width according to data that has been obtained by the analysis processing;

output audio data production means (11) for performing a series of processings of performing interpolation or thinning processing on the audio data in divided block units if necessary to thereby make data length thereof 1/r greater and thereby produce output audio data;

audio output means (12) for performing D/A conversion, at a sampling frequency f_o, of the thus-produced output audio data to thereby output a sound synchronized with an image; and

sampling frequency setting means for setting the respective sampling frequencies f_i and f_o so that the sampling frequency f_i used when performing A/D conversion, the sampling frequency f_o used when performing D/A conversion of the audio data to thereby produce an audio signal, and the changeable speed radio r may satisfy prescribed conditions.

5. An audio processing apparatus according to claim 4, wherein

as the prescribed conditions that are set by the sampling frequency setting means, when the sampling frequencies f_i and f_o and the changeable speed radio r satisfy the relationship of f_i/ f_o=r, there is used the sampling frequency f_i which is represented by an expression f_i=r≠ f_o; and

when the sampling frequencies f_i and f_o and the changeable speed ratio r are in the relationship of f_i/ f_o≠

r, there is used the sampling frequency f_i that is represented by an expression f_i=r·

f_o/c that includes a sampling frequency conversion coefficient c.

6. An audio processing apparatus according to claim 5, wherein

the output audio data production means (11) comprises means for monitoring time data of the audio signal read out from the recording medium and time data of the output audio data that has been obtained through the performance of the series of processes to thereby correct time non-coincidence that occurs between the audio signal and the output audio data.

7. A recording and reproduction apparatus comprising the audio processing apparatus according to claim 6.

8. A recording and reproduction apparatus comprising the audio processing apparatus according to claim 5.

9. A recording and reproduction apparatus comprising the audio processing apparatus according to claim 4.