JPH04362577A - Recording and reproducing method for compressed data - Google Patents

Abstract

PURPOSE:To offer a method capable of recording and reproducing compressed data without changing the mechanical system and the control system of a CD, etc., recording and reproducing normal data. CONSTITUTION:At the time of recording and reproducing the compressed data of compression magnification (n), by dividing a medium with unit recording time T, when these divided blocks are defined successively D11, D12,..., D1N, D21, D22,..., D2N,..., DM1, DM2,..., DMN, (where N: an integer smaller than n, M: an integer), the compressed data are recorded and reproduced in order of D11, D21,..., DM1, D12, D22,..., DM2,..., D1N, D2N,..., DMN. Then, by setting so as to be (N-1)XT>access time maximum value, the compressed data can be recorded and reproduced without changing the mechanical system and the control system of the CD, etc., recording and reproducing the normal data.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording and reproducing compressed data signals (particularly audio signals and video signals) on a medium (particularly a disk medium).

0002

2. Description of the Related Art Compact discs (CDs) have conventionally been used as disc storage media for digital audio signals.

0003

[Problems to be Solved by the Invention] The present invention is directed to these CDs.
The data writing/reading speed (in the case of CDs, the linear speed of disk rotation) can remain the same as before (therefore, there are no changes to the recording/playback mechanical system or control system), or the speed is inversely proportional to the compression ratio. Also, without reducing the
The present invention provides a method for recording and reproducing the data-compressed signal without impairing the continuity of reproduction during reproduction.

0004

[Means and actions for solving the problem] The following explanation is
CD as storage medium, data compression ratio n=N=4 (
However, the case where N is an integer equal to or less than n will be explained using FIG. 1 as an example.

[0005] The data area (see (a)) corresponding to n×T in CD playback time is divided into N (=4) ((b
)reference).

[0006] With the CD playback time obtained as a result of division (
Data areas (blocks) corresponding to n/N)×T=T are respectively D11, D12, D13, D14, D21, D22, D23, D24, D31, D32, D33, D34, etc.・・・・・・ ・・・・・・ D11, D12, ・・・D33, D34
, . . . Compressed data corresponding to (n×n/N)×T=n×T=4T in playback time can be recorded in each area (block).

[0007] Therefore, the linear velocity of disk rotation during data recording remains the same as before, D11, D21, D31,... (: first pass)
D12, D22, D32,..., (: second pass)
D13, D23, D33,..., (: third pass)
D14, D24, D34,..., (: 4th pass)
The compressed data is sequentially recorded on the disk in the order of D11, D21, D31,..., (: first pass) during playback, the same as during recording.
D12, D22, D32,..., (: second pass)
D13, D23, D33,..., (: third pass)
D14, D24, D34,..., (: 4th pass)
If the compressed data is read in the following order (see (c)), decompressed, and then played back, the data of each block will be
Each playback time becomes n×T (=4T) data ((d
)reference).

[0008] For example, if we consider the case where the first pass recording/playback is completed and the second pass recording/playback starts, the last block of the first pass will be near the outermost circumference of the disk, and the second The first blocks (D12) of the paths are each located near the innermost circumference (of the data area) of the disk.

[0009] During this access, in order to keep the recording/reproducing process from being interrupted, it is necessary to read the final data of the first pass and then while reproducing that data, that is, (N-1)
It is sufficient to finish the access operation during ×T=3T.
In other words, (N-1) x T > maximum access time
The N and T values may be set so that.

0010

[Example] Digital audio data (sampling frequency: 44.1Kz,
(quantization bit number: 16 bits, channel number: 2 left and right channels), compressed digital audio data is stored in blocks.

FIG. 2 shows an example of the arrangement of this compressed digital audio data. FIG. 2(a) shows a state in which the compressed digital audio data is arranged periodically in the order of first pass data, second pass data, third pass data, and fourth pass data for each block. . In FIGS. 2(b) and 2(c), one block of data is composed of a header part and a data part, and the header part is
Block synchronization signals and block state information (e.g.
(pass number, block number within the same pass, etc.).

FIG. 3 shows an example of the configuration of a signal processing section of a CD according to the present invention. In FIG. 3, (1) is a waveform shaping circuit that converts an analog signal from a disk into a binary signal;
(2) is a synchronization circuit that extracts a synchronization signal from the waveform shaping circuit output signal and performs bit synchronization and frame synchronization; (3) is a demodulation circuit that demodulates the EFM signal that is the synchronization circuit output signal; (4) is a demodulation circuit that demodulates the EFM signal that is the synchronization circuit output signal. , the demodulation circuit output signal is subjected to error correction processing and 1
The error correction circuit (5) that outputs 6-bit digital audio data is a channel separation circuit that separates the error correction circuit output signal into L/R channel signals in the case of a normal CD player. normal C
The signal processing section of the D player is configured.

On the other hand, the present invention provides the above (1), (2), and (3)
), (4), and (5), the following (6), (7), and (
8) by adding each circuit. That is, (6) is a block synchronization circuit which inputs the output of the error correction circuit and performs block synchronization of compressed digital audio data, and (7) is a block synchronization circuit that receives the error correction circuit output and synchronizes blocks of compressed digital audio data. and the block number, and outputs only the data block of a predetermined pass number to the compressed data reproduction processing circuit (8), which will be described later, and if the block number is the last block in the same pass number. Next, add 1 to the pass number of the block to be output to the compressed data reproduction processing circuit (8) (for example, if the pass number has been 2, set it to 3 next time), and also a pass number/block number discrimination circuit (8) that outputs an activation signal for moving the position of the CD to the innermost circumference of the data area of the CD to a control section (not shown) that controls the operation of the entire CD; ) is a reproduction processing circuit that decompresses one block of input compressed data and converts it into digital audio data.

[0014] Here, if the maximum access time is 2 seconds, then N=4, so T>2/3 seconds or more. That is, the memory capacity in the compressed data reproducing circuit (8) is set to a value that can store audio data equivalent to 2/3 seconds recorded on a normal CD.

[0015]

Effects of the Invention By applying the present invention to a CD and configuring and operating it as described above, the compressed data playback function (changing the disc rotation speed,
This can be realized by simply adding a relatively simple circuit (without changing the control unit accordingly). As a result, by recording compressed data on a conventional 8 cm CD, it is possible to play back up to 80 minutes of digital audio.

It goes without saying that the present invention is applicable not only to CDs but also to recording and reproducing digital audio and video data primarily on disk media.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a compressed data recording and reproducing method according to an embodiment of the present invention.

[Figure 2] Example of recording format of compressed data in the same embodiment

Claims (1)

[Claims] Claim 1: When recording and reproducing compressed data with a compression ratio n on a medium, the medium is divided into unit recording times T,
The divided blocks are sequentially D11, D12,..., D1N, D21, D22,..., D2N, ...... DM1, DM2,..., DMN, ( However, if N: an integer smaller than n, M: an integer), the compressed data will be D11, D21, ..., DM1, D12, D22, ..., DM2, ...... ... Recording and reproduction are performed in the order of D1N, D2N, ..., DMN, and N and T are set so that (N-1)×T>maximum access time. Compressed data recording and playback method.