JPH0530454A - Recording medium and search method therefor - Google Patents

Abstract

(57) [Summary] [Purpose] To search intra pictures at any speed. [Structure] The position of the sequence start code of the sequence immediately before and immediately after is recorded in the sequence header. Also, the GOP start code immediately before or immediately after is recorded in the GOP header. Furthermore, the position of the picture start code of the immediately preceding or following intra picture is recorded in the picture header.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium suitable for use in a case where a moving image is compressed and recorded on a recording medium such as a disk and is searched, and a search method therefor.

[0002]

2. Description of the Related Art When a moving image is compressed and recorded on a disc, in order to reduce redundancy between frames, there is a case where a prediction is performed from a preceding frame, a succeeding frame or a preceding frame and then a coding process. In this way, a picture (P picture) predicted from a temporally previous frame and a picture (B picture) predicted from a subsequent frame or a previous frame and a subsequent frame are:
If the reference frame is not decoded, the current frame cannot be constructed. Therefore, intra pictures (I pictures) that are encoded only within a frame are arranged at predetermined intervals.

That is, as shown in FIG. 5, intra pictures (intra-frame coded pictures) are arranged at predetermined intervals, the next P picture is predicted using this intra picture as a reference frame, and the next P picture is further predicted. A picture is predicted from a P picture or an intra picture that is previous in time. In addition, the B picture is predicted from the P picture that is temporally preceding and the intra picture that is temporally posterior in this embodiment.

[0004]

By the way, the disk on which the intra-frame coded picture (I picture) and the inter-frame coded picture (P picture, B picture) are recorded is searched (high speed reproduction). In this case, it is necessary to search for intra-frame coded pictures (intra pictures) and reproduce them sequentially. However, the conventional apparatus has a problem that it is difficult to perform the search at a desired speed because the position of the intra picture is unknown.

The present invention has been made in view of such a situation, and enables a search at a desired speed.

[0006]

According to a first aspect of the present invention, a start code of a preceding or following intra picture is recorded in a header of a picture, or a start of a previous or next group of picture is recorded in a header of a group of pictures. A code is recorded, or start codes of preceding and following sequences are recorded in the sequence header.

Further, in the recording medium search method according to the second aspect, an intra picture that is close to any of the start code of the intra picture, the start code of the group of pictures, or the start code of the sequence is searched for corresponding to the search speed. To be done.

[0008]

In the recording medium according to the first aspect of the present invention, the start code of the intra picture located before and after the picture is recorded in the header of the picture. Alternatively, the start code of the groove of picture before and after the group of picture is recorded in the header of the group of picture. Furthermore, start codes of the sequences before and after the sequence are recorded in the sequence header. Therefore,
The position of the intra picture to be read next can be detected from these start codes. As a result, high speed search becomes possible.

Further, in the recording medium search method according to the second aspect, for example, when the search speed is fast, an intra picture close to the start code of the preceding or succeeding sequence is searched, and when the search speed is slow, before or after. An intra picture close to the start code of the intra picture is searched. In the case of an intermediate speed, an intra picture close to the start code of the preceding or following group of pictures is searched. Therefore, the search can be executed at an arbitrary speed.

[0010]

2 is a block diagram showing the construction of an embodiment of a recording medium of the present invention and a reproducing apparatus therefor. A disc 1 as a recording medium is mounted in a drive 2 so that a recording signal can be reproduced. When the search command or the search speed is input, the controller 3 supplies an operation command corresponding to the input to the drive 2.
The drive 2 reproduces the information on the disc 1 and supplies the information on the current position (reproduction position) to the current position register 4 of the controller 3. Further, the image information is supplied to the inverse VLC and the multiplexing decoder 6. The multiplexing decoder 6 is the drive 2
The supplied data is decoded, the intra picture access information is supplied to the intra picture position register 5 of the controller 3, and the inverse quantization step size and the coefficient are output to the inverse quantization circuit 7. Further, the address generator 1
Supply motion vector to 1.

The output of the inverse quantization circuit 7 is the inverse DCT circuit 8
Is supplied to. The output of the inverse DCT circuit 8 is supplied to the frame memory 10 via the adder 9. Frame memory 1
The data read from 0 is output to a circuit (not shown), and the reference frame data is supplied to the adder 9. The address generator 11 is the frame memory 1
Generating an address of 0.

FIG. 3 shows the recording format of the disc 1. As shown in the figure, a picture start code and a picture header are added to the head of picture data of one frame (or field) to form one recording unit. A plurality of recording units are collected to form a group of pictures (GOP). GOP start code at the beginning of the group of pictures,
A GOP header is added. A plurality of group of pictures are collected to form one sequence. At the beginning of this sequence, a sequence start code and a sequence header are added.

A sequence is defined by a sequence start code at its start and a sequence end code at its end. An arbitrary number of sequence start codes can be arranged between the sequence start code and the sequence end code.

In each group of pictures, the leading picture is an I picture. Other pictures of the group of pictures are I pictures, P pictures or B pictures. Various information is recorded in the sequence header, GOP header and picture header. For example, the size of the moving image frame, the picture rate, the quantization weight matrix, and the like are recorded in the sequence header. It is prohibited to change the parameters in the sequence header except for the quantization weight matrix. Further, each header is provided with a user area so that each user can record arbitrary information therein.
In this embodiment, the front and rear position information is recorded in this user area.

That is, as shown in FIG. 4, the position of the sequence start code of the immediately preceding sequence and the position of the sequence start code of the immediately following sequence are recorded in the sequence header. Further, the position of the start code of the immediately preceding GOP and the position of the start code of the immediately following GOP are recorded in the GOP header. Furthermore, the position of the picture start code of the immediately preceding I picture and the position of the picture start code of the immediately following I picture are recorded in the picture header. These location information is
The address may be recorded, or the distance to the position (for example, the number of bytes) may be recorded.

Next, the operation of the recording medium reproducing apparatus shown in FIG. 2 will be described. The controller 3 outputs an operation command to the drive 2 when a normal reproduction command is issued from a circuit (not shown),
Play the disc 1. The drive 2 reproduces the disc 1, and reproduces the reproduced data by the inverse VLC and the multiplexing decoder 6
Supply to. The multiplexing decoder 6 performs inverse VLC (Inverse Variable Length Coding) processing on the input data. The multiplexing decoder 6 supplies the quantization step size data and coefficient data to the inverse quantization circuit 7 from the data obtained by decoding. The dequantization circuit 7 dequantizes the data supplied from the multiplexing decoder 6 with the input step size.

The data inversely quantized by the inverse quantization circuit 7 is supplied to the inverse DCT circuit 8 and subjected to inverse DCT (discrete or cosine transform). The output data of the inverse DCT circuit 8 is supplied to the frame memory 10 via the adder 9 and stored therein. When the data stored in the frame memory 10 is the data of the reference frame, the data is supplied to the adder 9 and added with the data supplied from the inverse DCT circuit 8. As a result, P picture data or B picture data is decoded. At this time, the address generator 11 generates an address corresponding to the motion vector supplied from the multiplexing decoder 6 and supplies it to the frame memory 10. The decoded picture is stored in the frame memory 10 in this manner, sequentially read out, and output to a circuit (not shown).

On the other hand, the drive 2 supplies the controller 3 with data concerning the reproduction position of the disc 1. The controller 3 stores this data in the current position register 4.
Further, the multiplexing decoder 6 reproduces the information stored in each of the above-mentioned headers, and supplies the intra picture access information among the information stored in the headers to the intra picture position register 5 for storage.

Next, when the search command and the speed of the search are commanded, the controller 3 executes the search operation according to the flow chart shown in FIG. That is, first, in step S1, the presence or absence of the search command is determined. When it is determined that the search command is input, the process proceeds to step S2, and the search speed and the search direction are read. Further, the process proceeds to step S3, and the current position register 4
The current position of the head is read from.

Next, in step S4, the target access point is calculated from the search speed, the search direction, and the current head position read in steps S2 and S3. Next, in step S5, an intra picture closest to the target access point calculated in step S4 is searched for from the intra picture position, register 5. The intra-picture position and register 5 stores the intra-picture position from the reproduction start position to the current position when the disc 1 is sequentially reproduced from the inner circumference to the outer circumference. Also, the position of the start code of the sequence next to the sequence containing the current position, the position of the start code of the group of picture next to the group of pictures containing the current position, and the position of the start code of the intra picture immediately after the current position. Is remembered. The controller 3 searches these data for the accessible intra picture closest to the target access point.

For example, when the commanded search speed is high, the sequence start code position immediately before or immediately after is searched. Also, if the commanded speed is slow,
The position of the start code of the immediately preceding or immediately following intra picture is searched. When the speed is an intermediate speed, the position of the start code of the GOP immediately before or immediately after is searched.

When the intra picture to be searched for is thus determined, the process proceeds to step S6, and the head is moved to that position. Steps S6 to S
It returns to 1 and the subsequent processing is repeatedly executed.

When the intra picture selected in step S5 is accessed, the position of the next intra picture is recorded therein. Therefore, it is possible to sequentially search intra pictures.

[0024]

As described above, according to the recording medium of the present invention, the start position of the preceding and following intra-frame coded pictures and the preceding and following groups are added to the picture header, the group of picture header or the sequence header. Since the information of the start position of the of picture or the information of the start position of the preceding and succeeding sequences is recorded respectively, the search can be executed at an arbitrary speed.

Further, according to the recording medium search method of the present invention, a frame close to either the start position of the intra-frame coded picture, the start position of the group of pictures, or the start position of the sequence corresponding to the search speed. Since the intra-coded picture is searched, the intra-coded picture can be searched quickly and reliably at a desired speed.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining the operation in the embodiment of FIG.

FIG. 2 is a block diagram showing the configuration of an embodiment of an apparatus to which the recording medium search method of the present invention is applied.

FIG. 3 is a diagram illustrating a recording format of the disc 1 of FIG.

FIG. 4 is a diagram illustrating a positional relationship between a sequence start code, a GOP start code, and an intra picture.

FIG. 5 is a diagram illustrating a relationship between an intra picture, a P picture, and a P picture.

[Explanation of symbols]

1 disc (recording medium) 2 drive 3 controller 4 Current position register 5 Intra picture position register 6 Multiplexing decoder 7 Inverse quantization circuit 8 Inverse DCT circuit 9 adder 10 frame memory 11 Address generator

Claims (2)

[Claims] 1. A recording medium in which an intra-frame coded picture and an inter-frame coded picture are recorded in a format having a group of pictures composed of a plurality of pictures and a sequence composed of a plurality of groups of pictures. In the header, the header of the group of pictures, or the header of the sequence, record the start position information of the preceding and following intra-frame coded pictures, the start position information of the preceding and following group of pictures, or the start position information of the preceding and following sequences. A recording medium characterized by the above. 2. An intra-frame coded picture and an inter-frame coded picture are recorded in a format having a group of pictures composed of a plurality of pictures and a sequence composed of a plurality of groups of pictures, and a header of the picture. , A record of the start position information of the preceding and following intra-frame coded pictures, the start position information of the preceding and following group of pictures, or the start position information of the preceding and following sequences in the header of the group of pictures or the header of the sequence In a recording medium search method for searching a medium, an intra-frame coded picture close to either the start position of the intra-frame coded picture, the start position of the group of pictures, or the start position of the sequence corresponding to the search speed. Search for Recording medium search method characterized by and.