JPH0486180A - Digital recording and reproducing method - Google Patents

Abstract

PURPOSE:To most suitably reproduce a picture in accordance with data included in read-out synchronizing blocks at the time of high-speed reproducing by decoding decodable data out of data included in read-out synchronizing blocks to reproduce the picture at the time of high-speed reproducing. CONSTITUTION:Encoded information of (m) blocks and DC components of respective blocks are inserted to a synchronizing block (x). Next, (i) encoded data out of encoded data of AC components of respective blocks are inserted to an area 22 in order from the first data, and (i+1)th and succeeding encoded data or respective blocks are inserted to areas 23, 24, and 25 in order from the first block. When encoded information and encoded data of DC components and low band AC components are read out, the picture is reproduced; but otherwise, the picture is not reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital recording and reproducing method that performs recording and reproducing using a sync plotter as one unit.

2. Description of the Related Art First, a digital VTR will be described as an example of a generally known digital recording/reproducing device. FIG. 5 is a schematic block diagram of the recording and reproducing system of a digital VTR. In FIG. 5, 51 is an input terminal, 52 is an A/D converter that converts an analog signal into a digital signal, and 53
54 is an error correction encoder that adds an error correction code; 54 is an interleave memory that rearranges input signals;
55 is a recording processing circuit that performs processing necessary for recording;
56 is a recording head. Next, 57 is a playback head, and 58 is a playback processing circuit that performs processing necessary for playback.
59 is a deinterleave memory for restoring the data rearranged by the interleave memory 54; 60 is an error correction decoder that performs error correction and error detection of recurrent signals; and 61 is a decoder for correcting error samples based on error flags. The error correction circuit 62 is a D/A converter.

To briefly explain the operation, first, in the recording systems 51 to 56, the input signal is digitized by the A/D converter 2, and the error correction encoder performs error correction encoding. Since many errors (errors) occur, the input signals are rearranged using an interleave memory 54. Finally, the synchronization pattern (
SYNC), address information, and other identification information (rD) are added, and a recording processing circuit performs the necessary processing for recording and records it on the tape. FIG. 6 shows the configuration of the sync block. In the figure, 1 is 5YNC12 is ID, and 3 is encoded data.

Next, in the reciprocating system, the playback head 57 reads the data recorded in units of sync plotters, passes through the playback processing circuit 58, returns the rearranged data in the deinterleave memory 59, and returns the rearranged data to the error correction decoder 60. Error correction and error detection are performed based on the error correction check symbol added during recording, and errors that cannot be corrected by the error correction decoder 60 are processed by the error correction circuit 61.
The correction is made based on the error flag in the D/A
The signal is converted into an analog signal by the converter 62 and output from the output terminal 63.

Next, readout of recorded data and re-transmission of read data will be described using examples of normal re-transmission and high-speed reproduction. Regarding reading of a sync block, it is assumed that when the trajectory of the center of the head passes over one sync block, the corresponding sync block can be read.

First, during normal playback, as shown in Figure 7(a), the data is scanned on the same locus that was scanned during recording, so the data in sync block units is read out as is, and the processing is reversed to that during recording. The image data is restored.

Next, during high-speed playback, the tape feed speed is faster than during normal playback, so the trajectory of the head scans over a plurality of tracks, as shown in FIG.

Therefore, it is impossible to read out all the sync blocks on one track, and only the sync plotter data shown in the shaded area shown in FIG. 7(b) is read out and reproduced.

Problems to be Solved by the Invention However, the digital recording and reproducing method described above has the following problems.

In general, image signals have a very large amount of information, so reducing the amount of information by compression encoding is an effective method. When introduced into a digital recording and reproducing device,
For example, encoded data obtained by compressing and encoding m blocks is inserted into n sync blocks and recorded. If only some sync plotters of n sync blocks are read out during high-speed playback, it is impossible to decode them if they do not contain encoding information. , if the data corresponding to the low-frequency components of the original image signal is not included, sufficient image quality cannot be obtained even if the image is decoded and reproduced. Furthermore, variable-length coding is often used to improve coding efficiency, but if variable-length coding is continuous with n zinc blocks, decoding the variable-length code requires one step. Because it is necessary to detect the break between two codes and one code, it is difficult to decode from encoded data in the middle, and it is difficult to decode correctly using only the encoded data of a part of the sync plotter. It is difficult.

In view of the problems of the prior art, an object of the present invention is to provide a digital recording and reproducing method that can perform optimal screen reproduction according to the data contained in the read sync plotter during high-speed reproduction. shall be.

Means for Solving the Problems The present invention blocks an input image signal, divides and inserts data obtained by compressing and encoding the m blocks into n sync blocks, and records the data. This digital recording and reproducing method is characterized in that when i sync plotters of a block are able to read data, decodable data in the data included in the one sync block is decoded to reproduce an image.

Effect of the present invention With the above-described configuration, even if an unreadable zinc block occurs among n sync blocks during high-speed playback, if the data contained in the read sync block is decodable, the data is decoded. The image is reproduced using only the data of the read sync block.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a method of inserting data after orthogonal transform encoding into a sync block in a digital recording and reproducing method according to an embodiment of the present invention.
blocks are encoded and the data is inserted into three sync blocks x, y, and z. Here 2. Figure 1 (a
) is a diagram showing the arrangement of data after orthogonal transform encoding of m blocks, 10, IL 12 is the DC component of each block, 13.14.15 is the AC component of each block is variable encoded. This is the encoded data. Also, Figure 1 (1
)) is a diagram showing the configuration of the sink block, where 1 is 5
YNV, 2X, 2y, 2Z are IDs, 20 is m blocks o
21 is the DC component of each block, and 22, 23, 24, 25 is the encoded data of the AC component of each block. Here, the data after orthogonal transformation is in the form shown in Figure 2, and the order of encoding the AC components is as shown in Figure 3, by scanning in order from the low frequency component and starting from the first block. It will be encoded. As a method of inserting encoded data into a zinc block, first, the encoding information of m blocks and the DC component of each block are inserted into the syntax block X. Next, the encoding of the AC component of each block is inserted. One piece of encoded data from the beginning of the data is inserted into 22, and (i
+1) Insert the encoded data of the 1st block in order from the 1st block to 23.24.25. Here, if A
When the C component is small and the AC component is encoded, the number of codes is 1
If less than 1 block is generated, a code indicating the end of the block (EOB) is inserted into 22 in FIG. (Figure 1).

Next, high-speed playback when recording is performed with sync blocks configured as described above will be explained.

Figure 4 shows the trajectory of the center of the head during high-speed playback and the sync blocks (shaded areas) that are played back, and (a)
, (b), and (C) are given as examples. Fourth
From the figure, the sync blocks that are read, the sync blocks that are not read, and the data that can be decoded and the data that are difficult to decode in the three cases can be summarized as shown in Table 1. In the case of , encoded information and DC
Since the AC component can be read out and the encoded data of the AC component included in the sync block X can be decoded,
The image is reproduced using the data of sync block X. Next, in the case of FIG. 4(b), the encoded information and the DC component can be read out as in the case of FIG. 4(a), and the code of the AC component included in the sync blocks x and y can be read out. Since the encoded data can be decoded, the image is reproduced using the data of the sync blocks x and y. Finally, in the case of FIG. 4(C), the encoded information and the DC component cannot be read out, and the encoded data of the AC component included in the sync blocks y and z is also difficult to decode. will not be played. In other words, the encoded information, the DC component, and the low-frequency A
If the encoded data of the C component is read out, the image is reproduced; otherwise, the image is not reproduced.

As explained above, according to this embodiment, optimal screen reproduction is performed depending on whether or not the sync plotter read out during high-speed reproduction contains information regarding encoding and low-frequency components of the original image. can be done.

Note that the number of blocks to be encoded and the corresponding sync blocks or the relationship thereof is only one example taken up in this embodiment, and can be set freely.

Furthermore, in this embodiment, the DC components are inserted all together into the first of the three sync plotters, but the DC components and AC components are inserted in each block in order starting from the first block.
The encoded data of the components may be inserted alternately.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, even if a sync block that cannot be read occurs during high-speed playback, optimal screen playback can be performed according to the read data in the sync plotter. The practical effects of this are significant.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the arrangement of encoded data and the structure of a sync block in a digital recording and reproducing method according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing components after orthogonal transformation, and FIG. The figure is an explanatory diagram showing an example of the coding order of AC components after orthogonal transformation, Figure 4 is an explanatory diagram showing the trajectory of the center of the head during high-speed reproduction and the sync plotter being reproduced, and Figure 5 is an explanatory diagram showing an example of the coding order of AC components after orthogonal transformation. A block diagram of a generally known digital recording and reproducing device, Fig. 6 is an explanatory diagram showing the configuration of a sync plotter, and Fig. 7 shows the trajectory of the center of the head and reproduced data during normal playback and high-speed playback. FIG. 1...5YNC, 2χ, 2y, 2z・
...ID. 10.11.12...DC component, 13, I4,
Engineering 5: AC component, 20: Encoded information, 21: DC component, 22.23.24.2
5... AC component. Name of agent: Patent attorney Shigetaka Awano Haka1 person first DCC domain chart (l Kamo L-----Ichicho) horizontal chart horizontal (cL) +f+fill (b) chart (C) Figure (α) Number of playback tapes (h phrase)

Claims (4)

[Claims] (1) The input image signal is divided into blocks, the m blocks are compressed and encoded, and the data is divided into n sync blocks and recorded. During high-speed playback, i sync blocks out of the n sync blocks are If it can be read, the i
A digital recording and reproducing method characterized in that an image is reproduced by decoding decodable data in data included in each sync block. (2) The digital recording and reproducing method according to claim (1), wherein orthogonal exchange is used for the compression encoding. (3) When the i sync blocks include information necessary for decoding, decoding decodable data among the data included in the i sync blocks to reproduce an image. A digital recording/reproducing method according to claim (1) or (2). (4) When the i sync blocks include data corresponding to low frequency components of the m blocks of the input signal, the data included in the i sync blocks 4. The digital recording and reproducing method according to claim 1, wherein the decodable data is decoded to reproduce the image.