JPH0479681A - Digital recording method - Google Patents

Abstract

PURPOSE:To reproduce a wide area of picture by inserting encoding information into one or (i) pieces of consecutive sync. blocks for recording. CONSTITUTION:(m) pieces of orthogonally transformed blocks are encoded and encoded data are inserted into three pieces of sync. blocks (a), (b), and (c). Regarding the component after orthogonal transformation encoding, components in areas represented by the A, B, and C in the figure are inserted into each sync. block (a), (b), and (c). Encoding information and important information, such as low-band components, etc., are collectively inserted into part of sync. blocks for recording. Therefore, even when only part of the sync. blocks can be read out, a wider area of a picture can be reproduced while high-band components are erased when the sync. blocks containing the encoding information and low-band components can be read out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a digital recording method in which recording is performed using a sync block as one unit.

2. Description of the Related Art Image signals generally have a very large amount of information, so when recording on a digital recording/reproducing device such as a digital VTR, a method of reducing the amount of information by compression encoding is used as an effective means. Here, examples of compression encoding techniques include Hadamard transform and discrete cosine transform (DCT).
), which uses orthogonal transform encoding. Orthogonal transform encoding encodes each frequency component obtained by dividing the input image signal into blocks and decomposing the frequency in units of blocks.For high-frequency components that are less affected by visual characteristics, The information amount of the original image signal can be reduced by techniques such as reducing the amount of data to be allocated.

Next, a recording and reproducing method for recording a signal compressed and encoded using the above method on a digital VTR will be described.

The data reduced by orthogonal transform encoding is recorded on the tape, and is divided into synchronization blocks each having a certain amount of data as the minimum synchronization unit during playback. FIG. 5 shows the configuration of the sync block. In Fig. 5, 5YNC is a synchronization pattern, 2 is identification information (ID) consisting of address information to indicate the position of recorded data on the screen, and data 3 is compression-encoded image data. . The arrangement of the sync blocks configured as described above on the tape is shown in FIG. 6, and the sync blocks are arranged on the tracks.

Each track is not only the trajectory of the recording head during recording, but also the trajectory of the playback head during normal playback. That is, during normal reproduction, the image data in each sync block can be reproduced by scanning the reproducing head along the same locus that the recording head scanned during recording, as shown in FIG. 7(a).

Next, a method for reproducing recorded data in special reproduction will be explained.

Figure 7 and others) are diagrams showing the trajectory of the playback head during high-speed playback, which is one of the special playbacks.During high-speed playback, the tape feed speed is faster than during normal playback, so the trajectory of the playback head is multiple. This results in scanning across tracks. Therefore, it is impossible to read out all the sync blocks on one track, and only the data in the sync blocks shown in the shaded area in FIG. 7(b) are read out and reproduced.

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

When m blocks are compressed and encoded and encoded data is inserted into n sync blocks, some sync blocks may not be read out of the n sync blocks during high-speed playback. For example, if j sync blocks out of n sync blocks cannot be read, the encoded data contained in the j sync blocks cannot be decoded. Only the area will be regenerated.

In view of the problems of the prior art, the present invention makes it possible to reproduce a wider area on the screen using the data in the read sync blocks, even if a sync block that cannot be read occurs during high-speed playback. The purpose is to provide a digital recording method.

Means for Solving the Problems The present invention blocks an input image signal, compresses and encodes the m blocks, and divides and inserts encoded data into n sync blocks for recording. Data consisting of encoding information necessary for decoding encoded data of a block and information of low frequency components of the input image signal corresponding to the m blocks among the encoded data of the m blocks, This digital recording method is characterized in that recording is performed by inserting into one sync block among the n sync blocks or i consecutive sync blocks.

Operation According to the present invention, encoded information and important information such as low-frequency components are collectively inserted into some sync blocks and recorded.

Example An embodiment 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, in which m blocks that have been orthogonally transformed are encoded. , encoded data a, b, c
It is inserted into three sink blocks. First, in Figure 1, 1 is 5YNC12a, 2b, 2c are ID, 10
is the encoding information necessary to decode m blocks,
11 is each DC component of m blocks, 12a, 12b,
12c is encoded data that has been compressed and encoded, and is inserted into 12a, 12b, and 12c in order from the low frequency component. That is, as shown in FIG. 2, the components in the regions A, B, and C after orthogonal transform encoding are inserted into the sync blocks a, b, and c, respectively.

Here, FIG. 3 shows an example of a device for realizing the above processing, in which 20 is an input terminal for an image signal, 21 is an A/D converter that converts the input signal into a digital signal, and 22 is an A/D converter for converting the input signal into a digital signal.
23 is an orthogonal transformer, 24 is an encoder, and 25 is a rearrangement memory.

That is, the data encoded by the encoder 22 is rearranged and written into the memory 25, and read out in order from the low-frequency components.

Next, high-speed playback when sync blocks are configured and recorded as described above will be explained. Regarding reading of a sync block, it is assumed that when the trajectory of the center line of the head passes over one sync block, the corresponding sync block can be read.

First, during normal reproduction, the same trajectory as that scanned during recording is scanned as shown in FIG. 7(a), so sync blocks a, b, and c are read out and reproduced as they are. Next, during high-speed reproduction, since the head trajectory scans across a plurality of tracks, some sync blocks among sync blocks a, b, and c occur that cannot be read. For example, in FIG. 4(a), a.

All sync blocks b and c are read out, but in FIG. 4(b), only sync block a shown in the shaded area is read out.
In FIG. 4(C), only the sync bronches a and b shown in the shaded area are read out. Here, since the sync block a contains the information necessary for decoding and the lowest frequency component, it is possible to reproduce the image in the area of the m blocks using only the low frequency component. , and when even sync block b is read out, even higher frequency components can be reproduced. In other words, high-frequency components are lost, causing fine details to disappear and block distortion to occur, but a wide range on the screen can be reproduced.

As explained above, according to this embodiment, even if only some sync blocks can be read out during high-speed playback, if the sync block including encoded information and low-frequency components can be read out, the high-frequency components can be read out. Although it is lost, it is possible to reclaim a larger area on the screen.

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

In addition, in this embodiment, the information necessary for decoding and the lowest frequency component are inserted into the first sync block of the three sync blocks, but the trajectory of the center of the head and the position of the sync block during high-speed playback are The sink block to be inserted can be freely determined depending on the relationship.

Furthermore, although this embodiment deals with encoding using orthogonal transformation, other encoding methods that perform block by block may also be used.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, even if a sync block that cannot be read occurs during high-speed playback, a wider area on the screen can be reproduced using the data in the read sync block. The practical effect is great.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a sync block in a digital recording method according to an embodiment of the present invention, and FIG. 2 is an orthogonal transformation inserted into each sync block in a digital recording method according to an embodiment of the present invention. FIG. 3 is a block diagram showing a configuration for realizing an embodiment of the digital recording method according to the present invention. FIG. 4 is a trajectory of the center of the head during high-speed playback. Figure 5 is an explanatory diagram showing the configuration of the sync block, Figure 6 is an explanatory diagram showing the arrangement of the sync blocks on the tape, and Figure 7 is the diagram during normal playback. FIG. 2 is an explanatory diagram showing the locus of the center of the head and reproduced data during high-speed reproduction. 22... Block generator, 23... Orthogonal transformer, 24... Encoder, 25...
Sorting memory. Name of agent: Patent attorney Shigetaka Awano (1 person)

Claims (1)

[Claims] Necessary when decoding the encoded data of the m blocks when the input image signal is divided into blocks and the encoded data obtained by compressing and encoding the m blocks is divided and inserted into n sync blocks and recorded. encoded information and the m
Out of the coded data of the m blocks, data consisting of low frequency component information of the input image signal corresponding to the m blocks is transferred to one sync block among the n sync blocks or to consecutive i sync blocks. A digital recording method characterized by recording by inserting into individual sync blocks.