JP3084811B2 - Recording medium search method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art When a moving image is compressed and recorded on a disk, in order to reduce redundancy between frames, there is a case where prediction is performed from a preceding, succeeding, or preceding or succeeding frame, and encoding is performed. 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 preceding and following frame are:
If the reference frame is not decoded, the current frame cannot be formed. Therefore, at predetermined intervals, intra pictures (I pictures) for which encoding is completed only within a frame are arranged.

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 temporally previous P picture or intra picture. Also, the B picture is predicted from the temporally preceding P picture and the temporally succeeding intra picture in this example .

[0004]

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

[0005] The present invention has been made in view of such circumstances, and enables a search at a desired speed.

[0006]

According to a first aspect of the present invention, there is provided a recording medium search method, comprising: a search speed, a search direction, and a head;
Calculation point to calculate the target access point from the current position of
Step and the target account calculated by the process of the calculation step.
Closest to the access point, the start position of the intra-frame coded picture, to search for a starting position, or the start position of the sequence of groups of pictures Sir
And a multi- step.

According to a second aspect of the present invention, there is provided a recording medium search apparatus.
Search speed, search direction and current position of the head
Calculating means for calculating the target access point;
The most closer to the calculated target access point, the start position of the intra-frame coded picture, the start position of the group of pictures, or the start position of the sequence
Characterized in that it comprises a search means for searching a location.

[0008]

In the recording medium search method according to the first aspect and the recording medium search apparatus according to the second aspect, a search is performed.
From the speed, search direction and current position of the head,
Access points are calculated and the calculated target access points
The start position of the intra-coded picture, the start position of the group of pictures, or the start position of the sequence, which is closest to the event, is searched.

[0009]

[0010]

FIG. 2 is a block diagram showing the configuration of an embodiment of a recording medium according to the present invention and a reproducing apparatus therefor. A disk 1 as a recording medium is mounted on a drive 2 so that a recording signal is reproduced. When a search command or a search speed is input, the controller 3 supplies an operation command corresponding to the input to the drive 2.
The drive 2 reproduces information on the disk 1 and supplies 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 multiplex decoder 6 is the drive 2
It decodes the supplied data, supplies the intra picture access information to the intra picture position register 5 of the controller 3, and outputs the inverse quantization step size and the coefficient to the inverse quantization circuit 7. Further, the address generator 1
1 is supplied with the motion vector.

The output of the inverse quantization circuit 7 is supplied to an inverse DCT circuit 8
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 data of the reference frame is supplied to the adder 9. The address generator 11 stores the frame memory 1
0 address is generated.

FIG. 3 shows a recording format of the disk 1. As shown in the drawing, a picture start code and a picture header are added to the head of the 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). The GOP start code is also at the top of the group of pictures,
A GOP header is added. A plurality of groups of pictures are collected to form one sequence. A sequence start code and a sequence header are also added to the head of this sequence.

The sequence is defined by a sequence start code at the beginning and a sequence end code at the 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, the GOP header, and the picture header. For example, the size of a picture frame of a moving image, a picture rate, a weight matrix for quantization, and the like are recorded in the sequence header. It is prohibited to change parameters in the sequence header other than the weight matrix for quantization. Also, each header is provided with a user area, in which each user can record arbitrary information.
In this embodiment, position information before and after 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. In the GOP header, 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. Further, in the picture header, the position of the picture start code of the immediately preceding I picture and the position of the picture start code of the immediately succeeding I picture are recorded. These location information
It may be recorded as an address, or may be recorded as a distance to the position (for example, the number of bytes).

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 normal reproduction is commanded from a circuit (not shown),
The disc 1 is played. The drive 2 reproduces the disk 1 and converts the reproduced data to the inverse VLC and the multiplex decoder 6.
To supply. The multiplex decoder 6 performs an inverse VLC (inverse variable length encoding) process on the input data. The multiplexing decoder 6 supplies quantization step size data and coefficient data from the data obtained by decoding to the inverse quantization circuit 7. The inverse quantization circuit 7 inversely quantizes the data supplied from the multiplex decoder 6 with the input step size.

The data inversely quantized by the inverse quantization circuit 7 is supplied to an inverse DCT circuit 8 and subjected to inverse DCT (discrete, cosine transform). Output data of the inverse DCT circuit 8 is supplied to the frame memory 10 via the adder 9 and stored. If the data stored in the frame memory 10 is reference frame data, the data is supplied to the adder 9 and added to the data supplied from the inverse DCT circuit 8. As a result, the data of the P picture or the B picture is decoded. At this time, the address generator 11 generates an address corresponding to the motion vector supplied from the multiplex decoder 6 and supplies the address to the frame memory 10. The decoded pictures are 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 data relating to the reproduction position of the disk 1 to the controller 3. The controller 3 stores this data in the current position register 4.
The multiplexing decoder 6 reproduces the information stored in each of the headers described above, and supplies the intra-picture access information among the information stored in the header to the intra-picture position register 5 and stores the same.

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

Next, the process proceeds to step S4, where a target access point is calculated from the search speed, the search direction and the current position of the head read in steps S2 and S3. Next, the process proceeds to step S5, and the intra picture closest to the target access point calculated in step S4 is searched from the intra picture position register 5 .
For example, when the disc 1 is sequentially reproduced from the inner periphery to the outer periphery, the position of the intra picture from the reproduction start position to the current position is stored in the intra picture position register 5 . Also, the position of the start code of the next sequence of the sequence including the current position, the position of the start code of the next group of picture after the group of picture including the current position, and the position of the start code of the intra picture immediately after the current position Is stored. The controller 3 searches these data for an accessible intra picture closest to the target access point.

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

When the intra picture to be searched is determined in this way, the process proceeds to step S6, and the head is moved to that position. Step S6 to Step S
The process returns to 1 and the subsequent processes are repeatedly executed.

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

[0024]

As described above, according to the recording medium search method according to the first aspect and the recording medium search apparatus according to the second aspect, the search speed, the search direction, and the current state of the head are determined.
The target access point is calculated from the position, and the calculated
The start position of the intra-coded picture, the start position of the group of pictures, or the start position of the sequence, which is closest to the target access point, so that the intra-coded pictures can be quickly and reliably obtained at a desired speed. You can search.

[0025]

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the operation in the embodiment of FIG. 2;

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 view for explaining a recording format of the disc 1 of FIG. 2;

FIG. 4 is a view for explaining a positional relationship among a sequence start code, a GOP start code, and an intra picture.

FIG. 5 is a view for explaining the relationship between an intra picture, a P picture, and a P picture;

[Explanation of symbols]

 Reference Signs List 1 disc (recording medium) 2 drive 3 controller 4 current position register 5 intra picture position register 6 multiplex decoder 7 inverse quantization circuit 8 inverse DCT circuit 9 adder 10 frame memory 11 address generator

Claims (2)

(57) [Claims] An intra-coded picture and an inter-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 is recorded. , Group of picture headers,
Alternatively, a recording for searching for a recording medium in which information of the start position of the preceding and following intra-frame coded pictures, information of the start position of the preceding and succeeding group of pictures, or information of the starting position of the preceding and succeeding sequences is recorded in the header of the sequence. In the medium search method, the search speed, the search direction, and the head
A calculating step of calculating a target access point; and the target access point calculated by the processing of the calculating step.
Closest to Seth point Sir searching the start position, the start position of the group of pictures, or the start position of the sequence of intra-frame coded picture
Recording medium search method which comprises the Chisuteppu. 2. An intra-frame coded picture and an inter-frame coded picture are recorded in a format having a group of pictures including a plurality of pictures and a sequence including a plurality of groups of pictures, and a header of the picture. , Group of picture headers,
Alternatively, a recording for searching for a recording medium in which information of the start position of the preceding and following intra-frame coded pictures, information of the start position of the preceding and succeeding group of pictures, or information of the starting position of the preceding and succeeding sequences is recorded in the header of the sequence. In the medium search device, the search speed, search direction and current position of the head
Calculating means for calculating a target access point, the target access point calculated by the calculating means
Closest to preparative, the start position of the intra-frame coded picture, a recording medium search apparatus characterized by comprising a search means for searching a start position, or the start position of the sequence of the group of pictures.