JPH08171779A - Method and device for reproducing compression data - Google Patents

Abstract

PURPOSE: To reproduce the compression coded data at the speed of ±1 time or below by delaying the recoverable data of a one before recording unit by recovery disable data amount and allowing the data to correspond to the recovery disable part. CONSTITUTION: In a VTR, data delay processing 21 is arranged between sub- band decoding processing 11 and JOG processing 7. The sub-band coding data decoded by the processing 11 are imparted with a fixed delay in the processing 21. Its delay amount depends upon the number of filter taps for calculating the number of samples of a basic block of a sub-band coding SBC. When the SBCed digital audio data are reproduced repeatedly in frame, the recovery disable part of the data occurs in the discontinuous point of the repeated data. Since JOG audio reproduction is not performed as it is, the recovery disable part by the processing 21 is shifted only by the amount entering the frame.

Description

Detailed Description of the Invention

[0001]

【table of contents】

 The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 9 and 10) Problem to be Solved by the Invention (FIGS. 11 to 13) Means for Solving the Problem (FIGS. 1 to 4) Action (FIGS. 1 to 4) ) Example (Figs. 1 to 8) (1) First example (Figs. 1 and 2) (2) Second example (Figs. 3 and 4) (3) Other examples (Figs. 5 to 5) 8) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed data reproducing method and a compressed data reproducing apparatus, and more particularly, it encodes a digital audio signal by a block coding compression method utilizing front-back correlation, and a plurality of coding blocks are recorded in one recording unit. Can be applied to what is called JOG audio reproduction in which digital audio data sequentially recorded as is reproduced at a speed of ± 1 times or less.

[0003]

2. Description of the Related Art Conventionally, in a video tape recorder (VTR) or the like in which a digital audio signal is recorded in a base band, the reproduction speed is changed to ± 1 times or less as in the case of analog longitudinal digital audio data, and the reproduction speed is adjusted to the speed. So-called JOG audio reproduction, which changes the frequency characteristic, is performed. For example, in the case of VTR1 shown in FIG. 9, JO of digital audio data is performed by the following procedure.
G audio playback is performed.

That is, the data read from the tape 2 by the head in the drum 3 is error-corrected by the ECC (code correction processing) 4 using the memory 5, and then the clock is converted by the clock conversion processing 5. Transfer is done. After that, the speed information and jump signal of the tape 2 are obtained from the drum 3 of the tape transport system or the system microcomputer, and the memory 8 such as Lagrange interpolation is applied to the reproduced data.
Is used to perform JOG processing 7, and audio is output as data output 9.

This JOG audio reproduction will be described in the case where one track or one frame of data is recorded in one track as shown in FIG. 10 (FIG. 10).
(A)). JOG audio playback is normal playback (Fig. 1
Since the speed of the tape 2 becomes slower than 0 (B), the head traces the track on which the data is recorded several times, and as a result, the data of the same track is repeatedly reproduced. Data repetition is obtained by jump signals from the system (FIG. 10 (C)).

Of the repeated data, only temporally continuous data is reconstructed on the memory 8 of the JOG processing 7. The data of the same field read again may be discarded. Then, the JOG reproduction process is completed by outputting the sound in the extended state on the time axis (FIG. 10 (D)). In this example, the analog output has a low frequency at 1/2 speed.

[0007]

As a method of recording digital audio data in a VTR, instead of the above-mentioned baseband recording method, a digital audio signal is frequency-divided and compression-encoded, and a plurality of encoding blocks are divided into frame units. There is a so-called sub-band coding method for recording in.

In the case of JOG audio reproduction of digital audio data compressed and encoded as described above, FIG.
As shown in FIG. 11 in which the same reference numerals are given to the portions corresponding to
The baseband digital audio data after decoding the compression-encoded data is processed. Therefore, the subband decoding process (SBC decoder) 11
Are arranged between the ECC processing 4 and the JOG processing 7 for the VTR 1 by baseband recording.

The problem here is the decoding of the sub-band coded data when the data is not continuous during JOG audio reproduction. That is, as shown in FIG. 12, in subband coding, one block is a basic unit sample for compression, which is several in a frame or field, and the compression coding is performed on the basis of the block. In this example, 320 samples are taken as one block, the number of subtape coding filters is 512, and JOG audio reproduction is one frame 1920.
An example of processing by repeating the sample is shown.

In order to completely decode one block into baseband digital data, one block and samples corresponding to the number of taps of the front and rear filters are required at the boundary. In practice, from the configuration of subband coding, 32O samples are decoded by calculating the data of 256 samples (512 in total) before and after the block start point. At this time, decoding is possible if the 512 samples are continuous, but if there are discontinuities (see FIG. 12).
(A)), the calculation of 512 samples including the part cannot obtain the correct result.

That is, in JOG audio reproduction of digital audio data that has been subband-encoded, correct data cannot be decoded at discontinuous points of repeated frames or fields. Therefore, as shown in FIG. 13, when subband-encoded digital audio data is to be reproduced as it is in JOG audio, there is a problem that noise is generated during audio output, and the above-mentioned JOG audio reproduction processing procedure is as follows. As it is, there is a problem that it cannot be applied to digital audio data which is sub-band coded.

The present invention has been made in consideration of the above points, and compresses digitally encoded digital audio data.
An object of the present invention is to propose a compressed data reproducing method and a compressed data reproducing apparatus capable of reproducing at a speed of 1 time or less.

[0013]

In order to solve such a problem, in the present invention, a digital audio signal is coded by a block coding compression method utilizing front-back correlation, and a plurality of coding blocks are set as one recording unit. In the compressed data reproducing method for reproducing sequentially recorded digital audio data, the digital audio data is ± 1
Of the digital audio data of the recording unit that is repeatedly played back when it is played back at a speed less than twice, the amount of data corresponding to the unrecoverable portion is the digital audio data of the previous continuous recording unit that can be restored. Is delayed so that it corresponds to the part that cannot be restored.

Further, in the present invention, the compressed data for reproducing the digital audio data in which the digital audio signal is coded by the block coding compression method utilizing the correlation between the front and rear, and the plurality of coded blocks are sequentially recorded as one recording unit. In the reproducing method, when the digital audio data is reproduced at a speed of ± 1 times or less, the digital audio data of the recording unit that is repeatedly reproduced can be continuously restored by the amount of data corresponding to the unrecoverable portion. The digital audio data of the previous recording unit is stored in the memory (31), and the unrecoverable part is replaced with the digital audio data in the memory (31).

Further, according to the present invention, the digital audio signal is coded by a block coding compression method utilizing front-back correlation, and compressed data for reproducing digital audio data sequentially recorded with a plurality of coded blocks as one recording unit. In the playback device (20), when the digital audio data is played back at a speed of ± 1 times or less, it is possible to restore the amount of data corresponding to the non-restorable portion of the digital audio data of the recording unit that is repeatedly played. A delay means (21) for delaying the continuous digital audio data of the immediately preceding recording unit is provided, and the digital audio data delayed by the delay means (21) is made to correspond to an unrecoverable portion.

Further, according to the present invention, the digital audio signal is encoded by a block coding compression method utilizing front and rear correlation, and compression is performed to reproduce digital audio data recorded sequentially by using a plurality of coding blocks as one recording unit. In the data reproducing device (30), when reproducing digital audio data at a speed of ± 1 times or less,
A memory means (31) is provided for storing digital audio data of the immediately preceding, continuously recoverable recording unit, which is the amount of data corresponding to the unrecoverable portion of the digital audio data of the recording unit that is repeatedly reproduced. The unrecoverable part is replaced with the digital audio data in the memory means (31).

[0017]

In the digital audio data of the recording unit that is repeatedly reproduced, the digital audio data of the immediately preceding recoverable recording unit that is recoverable is delayed by the amount of data corresponding to the unrecoverable portion, or the memory ( 31)
The digital audio data compressed and coded can be reproduced at a speed of ± 1 times or less by storing the data in a non-restorable part and storing or storing it in the non-restorable part.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment In FIG. 1 in which parts corresponding to those in FIG. 11 are assigned the same reference numerals, reference numeral 20 indicates a JOG audio reproducing method for subband-encoded digital audio data according to the present invention as a whole. Shows a first embodiment of a VTR to which
A fixed amount of delay in the data to be transferred to the subsequent JOG processing 7 is given to the subband-decoded digital audio data, and an indefinite section of the data is shifted to a section not used in the JOG processing 7, and the final Make sure that no noise remains on the audio output.

That is, in this VTR 20, a data delay process 21 is arranged between the subband decoding process 11 and the JOG process 7. The subband coded data decoded in the subband decoding process 11 is given a fixed delay in the data delay process 21. The amount of delay depends on the number of basic block samples for subband coding and the number of filter taps for calculation. Here, for simplicity, the basic block is set to 320 samples, the number of filter taps is set to 512, and the case where the JOG audio reproduction is repeated frame by frame is shown.

As described above in the related art, when the sub-band coded digital audio data is repeatedly reproduced in frame units, at the discontinuous points of the repeated data, as shown by the hatched area in FIG. , Unrecoverable part of data occurs. As it is, the JOG audio reproduction cannot be performed, and therefore the data delay process 21 described above shifts the unrecoverable portion by an amount included in the frame.

In the subband coding method under the conditions described above, a fixed delay of 224 samples is given as the data delay process 21 in FIG. 2 so that the JOG process 7 can process a portion including all indefinite intervals as a repeat frame. As a result, the data of that frame is not used, so
It is possible to prevent data in indefinite intervals from remaining in a series of data strings. Therefore, no noise is generated in the audio output after the reproduction performed by the JOG processing 7. Data processing in JOG processing 7
Data is selected in frame units based on the jump signal. Therefore, in this case, by shifting the indefinite section in the repeated frame, the data on the memory 8 of the JOG processing 7 can be restored as a noise-free data string.

According to the above construction, of the digital audio data of the recording unit that is repeatedly reproduced, a predetermined amount of data corresponding to the unrecoverable portion, the digital audio of the previous recording unit that can be restored continuously. By delaying the data so as to correspond to the non-restorable portion, it is possible to reproduce the JOG audio of the digital audio data compressed and encoded by the subband encoding method to obtain a noise-free audio output. .

(2) Second Embodiment In FIG. 3 in which parts corresponding to those in FIG. 1 are assigned the same reference numerals, reference numeral 30 generally indicates a JOG audio reproducing method for subband-encoded digital audio data according to the present invention. Shows a second embodiment of the VTR to which
For the subband-decoded digital audio data, the indefinite data portion of the frame or field having the discontinuity at the head is replaced with the immediately preceding frame data. In the JOG processing 7, the repeated data is not discarded but overwritten on the memory 8.

That is, in this VTR 30, a memory 31 and a data selector 32 are arranged between the subband decoding processing 11 and the JOG processing 7. Subband decoding process 1
The sub-band coded data decoded in 1 is temporarily stored in the memory 31 and read out in accordance with a jump signal given from the system control. This jump signal represents a repeated frame during JOG audio reproduction, and is actually processed in a sequence as shown in FIG.

First, data at the beginning of continuous frame processing (here, 256 samples) is stored in the memory 3 for each frame.
Write to 1 and update. Since this data is the data decoded in the part where the frames are continuous, it is correct as data. When the jump signal (FIG. 4 (B)) becomes active, it means that the frame is repeated. Therefore, the writing of data is stopped and the data written in the previous frame is read out. Through to replace the data at the beginning of the frame.

Originally, the data at the beginning of the frame in the non-decodable section of the discontinuous point is replaced with the previous frame, and the last frame of the repeated frame is completely decoded. This data is output to the JOG processing 7. In the JOG processing 7, instead of the above-described processing, the last data of the frame that is repeated at the data restoration stage on the memory 8 is adopted, so that an indefinite section does not remain in the final data.
As a concrete data processing in the JOG processing 7, the data is overwritten in the memory 8. Therefore, noise is not generated in the audio output reproduced by performing the JOG processing 7.

In the case of FIG. 4, the boundary between the frames F1 and F2 is decodable and written in the memory 31. After that, the jump signal becomes active, and the data is replaced with the data in the indefinite section at the beginning of the frame. Since the head data of the replaced frame is overwritten on the data of the previous frame F2 in the JOG processing 7,
A noise-free data sequence can be restored on the memory 8 of the JOG processing 7.

According to the above construction, of the digital audio data of the recording unit that is repeatedly reproduced, a predetermined amount of data corresponding to the unrecoverable portion, the digital audio of the immediately preceding recording unit that can be restored is used. By storing the data in the memory and replacing it with a non-restorable part, digital audio data compressed and encoded by the sub-band encoding method can be JOG audio reproduced to obtain a noise-free audio output. You can

(3) Other Embodiments In the above embodiments, the case where the subband coding block is locked to the frame or field, that is, the number of samples of the frame or field is an integer multiple of the number of samples in the block is described. However, the present invention can be applied even when not locked. For example, 384 subband coding blocks and 525/60 frame samples
The case of 1601/1602 samples of the system will be described. In practice, the subband coding (384 samples) block within 1601 or 1602 frame samples is
4.2 Blocks will exist. Therefore, the encoded data may be recorded for two frames as shown in FIG.

For decoding sub-band coding, one block and 256 samples before and after it are required.
When the frames are not continuous during audio reproduction, the indefinite section becomes larger than when it locks. The worst case is shown separately for the case before and after the frame. In this case, in the configuration of the first embodiment described above, the JOG audio reproduction described above can be performed by providing a delay amount of 256 + 383 = 639 samples as shown in FIG. Also, in the configuration of the second embodiment, as shown in FIG. 7, the data at the beginning of the frame is 256 + 383 in the worst case.
By storing 639 samples in the memory 31, the JOG audio reproduction described above can be performed.

In the above embodiment, the number of block samples that can be reproduced by the JOG audio is explained, but it may be impossible if the number of samples of the sub-band coding block exceeds a certain value. In practice, the number of block samples is expanded in the same way as described above, and in order to be able to process in blocks, in the part where continuous frames are reproduced,
The beginning of that frame must be correctly decoded. In any of the above-described first and second embodiments, there must be a portion where the data is always decoded and restored in the frame.

On the contrary, even if the number of samples in the indefinite section is continuous,
If the number of frames is less than or equal to the number of samples in the frame, JOG audio reproduction is possible by giving the worst amount of delay on the frame end side when the data is delayed as in the first embodiment. Further, when replacing the data of the second embodiment, JOG audio reproduction is possible by holding the worst part on the frame start side in the memory.

Therefore, as shown in FIG. 8, any block may be used as long as it has a block sample number equal to or less than 1/2 of the frame or field sample number.
Can play audio. In the figure, one frame is 1601/1602 samples, so the maximum number of block samples is 800 samples. In both the first and second embodiments,
JOG audio can be reproduced as long as all the data in the frame or field cannot be decoded.

If the JOG processing is performed by repeating frames or fields in this way, the unit block of subband coding can handle up to 1/2 of the number of samples, and the specific number of block samples is PAL. (625
/ 50) field processing for 960 samples, 4
80 samples or less, and for frame processing 1920 samples, 960 samples or less. NTSC (525/6
0) method field processing 800/801 samples,
400 samples or less, and in the case of frame processing 1601/1602 samples, 800 samples or less.

[0036]

As described above, according to the present invention, of the digital audio data of the recording unit to be repeatedly reproduced, a predetermined data amount corresponding to the non-restorable portion, which is the immediately preceding decodable continuous data. By compressing the digital audio data of the recording unit or storing it in the memory so as to correspond to the non-restorable part, the compression encoded digital audio data can be reproduced at a speed of ± 1 times or less. A data reproducing method and a compressed data reproducing device can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a VTR JOG audio reproduction processing procedure according to a first embodiment of a compressed data reproduction method of the present invention.

2 is a timing chart showing a JOG audio reproduction processing operation of FIG. 1. FIG.

FIG. 3 is a block diagram showing a VTR JOG audio reproduction processing procedure according to a second embodiment of the compressed data reproduction method of the present invention.

4 is a timing chart showing a JOG audio reproduction processing operation of FIG.

FIG. 5 is a schematic diagram used for explaining a discontinuous frame pattern in a 384-sample block.

6 is a timing chart showing the JOG audio reproduction processing operation of FIG. 1 for the discontinuous frame pattern of FIG.

7 is a timing chart showing the JOG audio reproduction processing operation of FIG. 3 for the discontinuous frame pattern of FIG.

FIG. 8 is a schematic diagram showing the maximum value of the number of blocks in the NTSC (525/60) system.

FIG. 9 is a block diagram showing a JOG audio reproduction processing procedure by a conventional baseband recording VTR.

10 is a timing chart showing the JOG audio reproduction processing operation of FIG.

FIG. 11 is a block diagram showing a JOG audio reproduction processing procedure in a conventional VTR in which compression encoded data is recorded.

12 is a timing chart showing a JOG audio reproduction processing operation of FIG. 11. FIG.

13 is a timing chart showing the JOG audio reproduction processing operation of FIG. 11. FIG.

[Explanation of symbols]

1, 10, 20, 30 ... VTR, 2 ... tape, 3 ...
… Drum, 4 …… ECC (code correction processing), 5,8 ……
Memory, 6 ... Clock conversion processing, 7 ... JOG
Processing, 9 ... Data output, 11 ... Subband decoding processing, 21 ... Data delay processing, 31 ... Memory, 3
2 ... Data selector.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G11B 20/18 M 8940-5D 570 E 8940-5D 572 G 8940-5D H03M 7/30 Z 9382- 5K (72) The inventor Jeremy Braley 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (6)

[Claims] 1. A compressed data reproducing method for reproducing digital audio data, wherein a digital audio signal is encoded by a block encoding compression method using front-back correlation, and a plurality of encoded blocks are sequentially recorded as one recording unit to reproduce digital audio data. When the digital audio data is played back at a speed of ± 1 times or less, a continuous data which can be restored by the amount of data corresponding to the non-restorable portion of the digital audio data of the recording unit that is repeatedly played back. Delay the above digital audio data of the previous recording unit,
A compressed data reproducing method characterized in that it corresponds to the unrestorable portion. 2. A compressed data reproducing method for reproducing digital audio data in which a digital audio signal is encoded by a block encoding compression method using front-back correlation, and a plurality of encoded blocks are sequentially recorded as one recording unit. When the digital audio data is played back at a speed of ± 1 times or less, a continuous data which can be restored by the amount of data corresponding to the non-restorable portion of the digital audio data of the recording unit that is repeatedly played back. A compressed data reproducing method characterized in that the digital audio data of the immediately preceding recording unit is stored in a memory, and the non-restorable portion is replaced with the digital audio data in the memory. 3. The digital audio signal is a block coding compression method in which the number of samples of the encoded block is 1/2 or less of the number of samples when the digital audio data is reproduced at a speed of ± 1 times or less. 3. The compressed data reproducing method according to claim 1, wherein the compressed data is encoded. 4. A compressed data reproducing apparatus which reproduces digital audio data in which a digital audio signal is encoded by a block encoding compression method using front-back correlation and a plurality of encoded blocks are sequentially recorded as one recording unit. When the digital audio data is played back at a speed of ± 1 times or less, a continuous data which can be restored by the amount of data corresponding to the non-restorable portion of the digital audio data of the recording unit that is repeatedly played back. A compressed data reproducing apparatus comprising delay means for delaying the digital audio data of the immediately preceding recording unit, and making the digital audio data delayed by the delay means correspond to an unrecoverable portion. 5. A compressed data reproducing apparatus for reproducing a digital audio data, which encodes a digital audio signal by a block coding compression method using front-back correlation, and reproduces digital audio data sequentially recorded by using a plurality of coding blocks as one recording unit. When the digital audio data is played back at a speed of ± 1 times or less, a continuous data which can be restored by the amount of data corresponding to the non-restorable portion of the digital audio data of the recording unit that is repeatedly played back. A compressed data reproducing apparatus comprising memory means for storing the digital audio data of the immediately preceding recording unit, and replacing the non-restorable portion with the digital audio data in the memory means. 6. The digital audio signal is encoded by a block coding compression method in which the number of coded blocks is 1/2 or less of the number of samples when the digital audio data is reproduced at a speed of ± 1 times or less. The compressed data reproducing apparatus according to claim 4 or 5, which is encoded.