JPH08293157A - Recording and reproducing method for variable frame length high efficiency coded data - Google Patents

Abstract

PURPOSE: To easily perform the fast-forwarding reproducing of the forward and reverse directions by the data jumping of a block unit by recording frame position information indicating the frame starting positions of all high efficiency coded data in a block. CONSTITUTION: In a frame position information calculating part 13, frame position information indicating the head positions of frames are outputted from a header synchronizing signal and a block synchronizing signal. Recorded block data having a fixed data length are reproduced in a reproducing device. The reproducing device is constituted of a frame position information part 41, a header extracting part 42 and a decoding part 43. Then, the header extracting part 42 outputs a header position signal from a reproducing block synchronizing signal and the frame position information. The decoder part 43 outputs decoded data by decoding the high efficiency coded data by using the effective data of the high efficiency coded data shown by an effective data flag and the header position signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recording / reproducing highly efficient coded data having a variable frame length with high data compression efficiency.

[0002]

2. Description of the Related Art In recent years, with the progress and development of high-efficiency coding technology, the number of data per frame of high-efficiency coded data such as voice and image, that is, a variable frame length high-efficiency code is changed. Technology has been attracting attention.

An example of such a high-efficiency coding technique is MPEG (Moving Pictu), which is a joint working group of IS0 (International Organization for Standardization) and IEC (International Electrotechnical Commission).
re Experts Group) in 1993 ISO / IEC
The MPEG1 standard is standardized as the 11172 standard.

As an example of such high-efficiency encoded data having a variable frame length, a layer 1 bit stream of the MPEG1 audio standard, which is a high-efficiency encoded data standard for audio signals, will be described.

[0005] Here, from Chapter 8 "What is high-fidelity audio compatible MPEG audio?" Of "Latest MPEG textbook" (edited by Hiroshi Fujiwara, multimedia study group) published by ASCII Corporation in 1994. Explain by quoting.

FIG. 6 shows the structure of a bit stream of high-efficiency encoded data of Layer 1 of the MPEG1 audio standard, and the upper part (a) shows the structure of a bit stream of high-efficiency encoded data of 1 frame.

Here, a frame is a minimum unit that can be independently decoded into an audio signal, and always includes a fixed number of samples (384 samples in layer 1) of data. Therefore, in layer 1, the number of bits of high-efficiency coded data for one frame is calculated by 384 × bit rate / sampling frequency on average.

Further, in Layer 1, it is a rule that the number of bits of one frame is always adjusted to a multiple of 32 bits, so the number of bits obtained by the average number of bits is 3
If it is not a multiple of 2 bits, a frame having 32 more bits (frame with padding bits of '1') is created by using the padding bits of the header to match the average number of bits in a plurality of frames.

One frame is composed of a header, an optional error check (CRC 16 bits), audio data and ancillary data (external data other than audio).

The lower part (b) of FIG. 6 shows the structure of the header. The 12-bit sync word and the 1-bit ID are all "1" and can be used as a sync pattern. However, various bit patterns can appear in parts other than the header of MPEG1 audio, and the same pattern as the synchronization pattern may appear in parts other than the header. Therefore, in the decoder, it is necessary to confirm the synchronization pattern with the predetermined header multiple times in order to avoid erroneous synchronization. This can reduce the probability of false synchronization to almost zero.

The parameters shown in the lower part (b) of FIG. 6 influence the frame length by the bit rate index and the sampling frequency, which will be described. The bit rate index is a parameter that specifies the bit rate and can be changed to generate highly efficient coded data with a variable frame length. Sampling frequency is 32kHz, 44.1kHz, 48
You can select from three types of kHz.

The ISO / IEC 11172 standard actually deals with variable bit rate data, that is, variable frame length data, in order to minimize delay time and hardware complexity for the layer 1 decoding device. It is not obligatory. However, it is possible to make a decoder corresponding to layer 1 data having a variable frame length, and the recording / reproducing apparatus described below uses a decoder corresponding to such highly efficient data having a variable frame length. Shall have.

First, such highly efficient coded data of variable frame length is divided into blocks of fixed data length,
A data recording / reproducing format used in a conventional device for recording and reproducing in a memory such as a disk, a tape, or a semiconductor will be described.

FIG. 7 shows an example of a data recording / reproducing format of such conventional variable frame length high efficiency encoded data.
FIG. 7A shows the overall structure of the data recording / reproducing format. At the beginning, for controlling the playback of each program,
There is program control information such as a program start address and a reproduction time, and a plurality of (L in this figure) program data are recorded subsequently.

FIG. 7B shows the structure of each program. Each program is composed of a fixed data length block of a fixed number of data so that the recording and reproducing processes are easy. In the figure, the value of M, which represents the number of blocks forming each program, differs depending on the program.

FIG. 7C shows the structure of each block. High-efficiency coded data composed of N frames of variable data length (N is the number of frames in which at least the head data of a frame is recorded in a block) is recorded. In the same figure, the head of the block is a frame extending from the previous block, (N-1) complete frame data is recorded in this block, and the last Nth frame is recorded in the next block. A frame is a variable data length frame in which the number of data forming each frame is different, and the value of N differs depending on the block.

[0017]

In such a conventional variable frame length high efficiency coded data recording / reproducing apparatus, in order to perform fast forward reproduction in the forward direction or the backward direction, when the data is skipped and reproduced, There is a problem that it takes time to extract the frame of the efficiency coded data.

FIG. 8 shows the configuration of a conventional reproducing apparatus for variable frame length high efficiency coded data. Reference numeral 81 is a synchronization pattern extraction unit, 82 is a header candidate extraction unit, 83 is a synchronization state control unit, and 84 is a decoding unit. The input data to this reproducing device is reproduction block data, that is, high-efficiency encoded data itself.

When the high-efficiency coded data is input, the synchronization pattern detection unit 81 sets a predetermined synchronization pattern, in this case, a pattern of all 13 bits "1" consisting of a synchronization word and an ID, as the synchronization pattern, and uses this synchronization pattern. When detected, the sync pattern position signal is set to "1" and output. For example, when the high-efficiency coded data shown in FIG. 9A is input, it corresponds to the synchronization pattern shown by the hatched portion in FIG. 9B.
The sync pattern position signal shown in is output. Next, the header candidate extraction unit 82 extracts a header candidate based on the synchronization pattern position signal detected by the synchronization pattern detection unit 81, calculates the frame length from this header candidate, and calculates the header position of the next frame as shown in FIG. It is output as a header prediction signal as shown in (c). The synchronization state control unit 83 confirms whether or not the synchronization pattern is detected at the position predicted by the header position prediction signal, and if the synchronization pattern is not detected, it is not the header synchronization pattern. Is set to '0', and when the synchronization pattern is detected, the header predicted position signal is output as it is as the header position signal as shown in (d) of FIG. The decoding unit 84 receives the high-efficiency coded data as input, decodes the frame in which the header position signal is "1", and outputs the decoded data.

The sync pattern S0 shown in FIG. 9 is a pseudo sync pattern included in the audio data, not a sync pattern included in the header. Therefore, the header position prediction signal predicted based on the synchronization pattern S0 does not have a synchronization pattern, and the synchronization state control unit 83 determines that the synchronization is not established, and the header position signal becomes “0”. Since the synchronization pattern S1 next to S0 is inside the frame predicted by S0, the synchronization state control unit 83 ignores it. The header is extracted again with the next synchronization pattern S2, the frame length is predicted based on this header, and this time, since the synchronization pattern exists at the position predicted by the header position prediction signal, the synchronization state control unit is in the synchronization state. Then, the header position prediction signal is output as a header position signal, and the decoding unit 84 starts decoding.

As in the example shown in FIG. 9, a conventional high-efficiency coded data reproducing apparatus may take two or more frames to perform frame extraction, and data before frame extraction becomes possible. Since the others are discarded, the valid data that can be decrypted is reduced.

It is an object of the present invention to realize a recording / reproducing apparatus for high-efficiency coded data of a variable frame length, which can easily perform forward or backward fast-forward reproduction due to interlaced data.

[0023]

According to the method of recording and reproducing variable frame length high efficiency encoded data of claim 1, the variable frame length high efficiency encoded data is divided into blocks of fixed data length and recorded and reproduced. In doing so, in the block, high-efficiency coded data and frame position information indicating the frame start position of the first frame of the high-efficiency coded data in the block are recorded, and the high-efficiency is recorded using the frame position information. It is characterized in that the encoded data is reproduced in frame units.

According to the variable frame length high efficiency coded data recording / reproducing method of the second aspect, when the variable frame length high efficiency coded data is divided into blocks of fixed data length and recorded and reproduced, the blocks are recorded in the blocks. Recording high-efficiency coded data and frame position information indicating frame start positions of the first frame and the last frame of the high-efficiency coded data in the block, and using the frame position information to record the high-efficiency code. It is characterized in that the encoded data is reproduced in frame units.

According to the variable frame length high efficiency coded data recording / reproducing method of the third aspect, the variable frame length high efficiency coded data is divided into blocks having a fixed data length to be recorded and reproduced. In, high-efficiency coded data, frame position information representing the frame start position of all the frames of the high-efficiency coded data in the block is recorded, the high-efficiency coded data using the frame position information. It is characterized by reproducing in frame units.

[0026]

According to the structure of the first aspect, at the time of reproduction, the frame position information indicating the frame start position of the first frame in the block is used to perform frame extraction of the high efficiency coded data and to extract the data in block units. Playback from the middle of the program by skipping over and fast-forward playback can be easily performed.

According to the structure of claim 2, at the time of reproduction, the frame position information representing the first frame and the last frame start position in the block is used to extract the frame of the high-efficiency coded data, and at the same time, to extract the frame in the block. By indicating the effective data of the high-efficiency encoded data in units of frames, the fast-forward reproduction can be performed more easily by skipping the data in units of blocks.

According to the structure of claim 3, at the time of reproduction, by using the frame position information indicating the frame start positions of all the frames of the high-efficiency coded data in the block, any of the high-efficiency coded data in the block is selected. By performing frame extraction of frames, it is possible to easily perform fast-forward reproduction in the forward direction and the reverse direction by skipping data in block units.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for recording / reproducing variable frame length high efficiency coded data according to the present invention will be described below with reference to specific embodiments.

FIG. 1 shows the structure of a recording apparatus used for implementing the present invention. This recording device includes an encoding unit 11, a block synchronization signal generation unit 12, a frame position information calculation unit 13, and a multiplexer 14. 2 (a)-
(D) shows the timing of the same apparatus, (a) is high-efficiency coded data, (b) is a header position signal, (c) is a block synchronization signal, and (d) is recording block data.

When data is input to the encoding unit 11, the encoding unit 11 generates and outputs highly efficient encoded data of variable frame length. In this embodiment, as in the conventional example, the data input to the encoding unit 11 is an audio signal, and the output high efficiency encoded data is MPEG1 layer 1 high efficiency encoded data.

The block sync signal generator 12 generates a block sync signal having a fixed data length. The period in which the block synchronization signal is '1' corresponds to the data length of the frame position information to be inserted into the block data later.

As shown by the shaded area in FIG. 2A, the coding unit 11 does not output the high-efficiency coded data while the block sync signal is "1". The encoding unit 11 outputs high-efficiency encoded data having a variable frame length and outputs a header position signal indicating the position of the header at the beginning of the frame of the high-efficiency encoded data, as shown in (b) of FIG. .

The frame position information calculation unit 13 uses the header synchronization signal and the block synchronization signal to determine the frame position information indicating the start position of the block and the frame start position of the i-th frame of the high-efficiency coded data in the block (for example, the block The number of data in units of 8 bits from the beginning) is output. In the first embodiment, the frame position of the first frame of the high efficiency coded data in the block is output as the frame position information.

The multiplexer 14 switches the frame position information and the high-efficiency coded data by using the block synchronization signal to generate and output the recording block data shown in FIG. 2D.

FIG. 3 shows a data recording / reproducing format used in the recording / reproducing apparatus for variable frame length high efficiency encoded data in the embodiment of the present invention. FIG. 3A shows the entire structure of the data recording / reproducing format. At the top is program control information such as the start address of the program for controlling the reproduction of each program and the reproduction time, and subsequently, a plurality (L in this figure) of program data is recorded.

FIG. 3B is a diagram showing the structure of each program, and each program is composed of fixed data length blocks of a fixed number of data so that recording and reproducing processes can be easily performed. M representing the number of blocks that make up each program
The value of depends on the program.

FIG. 3 (c) is a diagram showing the structure of each block, which has N variable data lengths (N is the number of frames in which at least the beginning data of the frame is recorded).
High-efficiency coded data composed of frames is recorded. The head of the block is the frame position information described above, and a frame extending from the previous block to the next. Below, (N-1) complete frame data is recorded in this block.
The last Nth frame is recorded over the next block. The value of N depends on the block.

The block data having the fixed data length thus recorded is reproduced by the reproducing apparatus shown in FIG.
This reproducing apparatus includes a frame position information extracting section 41, a header extracting section 42, and a decoding section 43. 5A to 5D show the timing of the device,
(A) is reproduction block data, (b) is a reproduction block synchronization signal, (c) is a header position signal, and (d) is a data valid flag.

When the reproduction block data and the reproduction block synchronization signal corresponding to the reproduction block data are input, the frame position information extracting section 41 extracts the frame position information. The frame position information extraction unit 41 sets a valid data flag (high efficiency coded data is valid during the period of “1”) indicating a valid data position as high efficiency coded data in the reproduction block data excluding frame position information. It is output (see (d) of FIG. 5).

The header extraction unit 42 outputs a header position signal indicating the header position at the frame head of the i-th frame of the high-efficiency coded data in the block from the reproduced block synchronization signal and the frame position information. In the recording apparatus of the first embodiment, only the frame head position of the first frame is recorded, and the header extraction unit 42 extracts the header from the effective data of the high efficiency encoded data indicated by the effective data flag. Then, the frame length of a frame having a header is calculated, and the header position of the next frame is output as a header position signal. Thereafter, this process is repeated to generate and output signals representing all header positions in the block (see (b) in FIG. 2).

The decoding unit 43 decodes the high efficiency coded data using the valid data of the high efficiency coded data indicated by the valid data flag and the header position signal, and outputs the decoded data.

As described above, according to the first embodiment, the head position of the first frame of the high-efficiency coded data in the block is recorded as frame position information, and the high-efficiency code is used by using the frame position information during reproduction. By extracting the frame of the encoded data, it is possible to easily perform the reproduction from the middle of the program or the fast-forward reproduction by skipping the data of the block unit.

In the first embodiment, the frame position information indicating the frame start position of the first frame of the high-efficiency coded data in the block is recorded as the frame position information and used for reproduction. The same effect can be expected in the second embodiment in which the contents of is changed as follows.

In the second embodiment, the frame position information indicating the frame start positions of the first frame and the last frame of the high efficiency coded data in the block is recorded, and the high efficiency is recorded by using the frame position information. By extracting the frame of the coded data and indicating the effective data range of the high efficiency coded data in the block by using the frame position information of the last frame of the high efficiency coded data in the block, Fast-forward playback by skipping over can be performed more easily.

The same effect can be expected in the third embodiment in which the contents of the frame position information are changed as follows.
In the third embodiment, the frame head positions of all the high-efficiency coded data in the block are recorded as frame position information, and the frame position information is used at the time of reproduction to determine an arbitrary high-efficiency coded data in the block. By performing frame extraction of frames, it is possible to easily perform fast-forward reproduction in the forward direction and the reverse direction by skipping data in block units.

[0047]

According to the variable frame length high efficiency coded data recording / reproducing method of the present invention, the frame position information indicating the start position of the first frame of the high efficiency coded data in the block is recorded and reproduced. By performing frame extraction of the high-efficiency coded data by using the frame position information, it is possible to easily perform reproduction from the middle of the program or fast-forward reproduction by skipping data in block units.

According to the variable frame length high efficiency coded data recording / reproducing method of the second aspect, the frame position information indicating the head positions of the first and last frames of the high efficiency coded data in the block is recorded and reproduced. At the same time, the frame position information is used to extract the frame of the high-efficiency encoded data, and the effective data range of the high-efficiency encoded data in the block is controlled in the frame unit, so that the fast-forward reproduction by the interlacing of the data in the block unit is performed. Can be done more easily.

According to the variable frame length high efficiency coded data recording / reproducing method of the third aspect, the frame position information indicating the frame head position of all the high efficiency coded data in the block is recorded and the frame is reproduced at the time of reproducing. By performing frame extraction of an arbitrary frame of high-efficiency coded data data in a block using the position information, it is possible to easily perform fast-forward reproduction in the forward direction and the backward direction by skipping data in block units.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a recording device used for recording in a recording / reproducing method of variable frame length high efficiency encoded data of the present invention.

FIG. 2 is a timing diagram illustrating the configuration of the recording apparatus according to the embodiment.

FIG. 3 is an explanatory diagram showing a data recording / reproducing format of the embodiment.

FIG. 4 is a configuration diagram of a playback device used for playback of the embodiment.

FIG. 5 is a timing chart for explaining the operation of the reproducing apparatus of the embodiment.

FIG. 6 is a configuration diagram of a frame-wise bit stream of high-efficiency encoded data.

FIG. 7 is an explanatory diagram of a data recording / reproducing method used in a conventional variable frame length high efficiency encoded data recording / reproducing apparatus.

FIG. 8 is a configuration diagram of a conventional variable frame length highly efficient encoded data reproducing apparatus.

FIG. 9 is a timing chart for explaining problems in the operation of the conventional reproducing apparatus for variable frame length high efficiency encoded data.

[Explanation of symbols]

 11 Encoding Unit 12 Block Synchronization Signal Generation Unit 13 Frame Position Information Calculation Unit 14 Multiplexer 41 Frame Position Information Extraction Unit 42 Header Extraction Unit 43 Decoding Unit

Claims (6)

[Claims] 1. When dividing variable frame length high-efficiency encoded data into blocks of fixed data length and recording and reproducing the blocks, the high-efficiency encoded data and the first high-efficiency encoded data in the block are recorded in the block. And a frame position information indicating a frame head position of the frame, and using the frame position information, the high-efficiency encoded data is reproduced on a frame-by-frame basis. 2. When the variable frame length high efficiency coded data is divided into blocks of fixed data length and recorded and reproduced, the high efficiency coded data and the high efficiency coded data in the block are recorded in the block. Recording of frame position information indicating the frame start position of the first frame and the last frame, and recording of variable frame length high efficiency coded data for reproducing the high efficiency coded data in frame units using the frame position information. How to play. 3. The variable frame length high-efficiency coded data is divided into blocks of fixed data length, recorded and reproduced, and the high-efficiency coded data in the block and the high-efficiency coded data in the block are recorded. And the frame position information indicating the frame start positions of all the frames, and reproducing and recording the high-efficiency coded data in frame units using the frame position information. 4. When reproducing variable frame length high-efficiency encoded data divided into fixed data length blocks and recorded, the high-efficiency encoded data recorded in the block and the high-efficiency encoding in the block are reproduced. A reproducing method of variable frame length high efficiency coded data, wherein the high efficiency coded data is reproduced in frame units by using frame position information indicating a frame head position of a first frame of data. 5. When reproducing variable frame length high efficiency encoded data divided into fixed data length blocks and recorded, the high efficiency encoded data recorded in the blocks and the high efficiency encoded data recorded in the blocks are reproduced. A variable frame length high-efficiency coded data for reproducing the high-efficiency coded data on a frame-by-frame basis using frame position information indicating the frame start position of the first frame and the last frame of the high-efficiency coded data How to play. 6. The high-efficiency encoded data recorded in the block and the high-efficiency encoded in the block when reproducing the variable frame length high-efficiency encoded data divided into blocks of fixed data length and recorded. A method for reproducing variable frame length high efficiency coded data, which reproduces the high efficiency coded data in frame units using frame position information indicating the frame head positions of all the frames of data.