JP2000278631A - Image data recorder, recording method and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image data recorder that efficiently accesses specific image data in the case of reproduction of a disk at an N multiple speed on which compression coded image data are recorded, and to provide its recording and reproducing method. SOLUTION: In the case of dividedly recording image data to a disk in the access unit of the disk, the data are recorded while an index to access the access unit to which specific image data are recorded is added to the data. In the case of reproducing this disk at an N multiple speed, the index is read from the disk at an interval of a prescribed number of access units set in response to the number of double speeds, a recording address in the access unit on which the specific image data are recorded is detected on the basis of the read index and the recording data are read from the read access unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data recording apparatus, a recording method and a reproducing method for recording compression-encoded image data on a disk-shaped recording medium and reproducing the data at N (integer) times.

[0002]

2. Description of the Related Art As is well known, for example, MPEG (Moving)
Image data compressed and encoded in accordance with the Picture Image Coding Experts Group (HDD)
In the case of recording on a disk-shaped recording medium by an isk drive or the like and reproducing at N times speed, an intra-frame coded image, that is, an I (Intra) picture, is efficiently accessed from among the image data recorded on the disk Is required.

In order to efficiently access an I picture at the time of N-times speed reproduction as described above, for example, Japanese Patent Laid-Open No.
Various access means have been developed as disclosed in Japanese Patent Application Laid-Open No. 0-257439 and Japanese Patent Application Laid-Open No. 8-273296.

First, the access means disclosed in Japanese Patent Application Laid-Open No. H10-257439 is based on the assumption that data having a fixed frame size of compression-encoded image data is handled, and is set to a multiple of an access unit. By adding dummy data to the hard disk and recording it on the hard disk, the position on the hard disk of the frame to be accessed during N-times speed reproduction can be specified by a simple calculation.

In the access means disclosed in Japanese Patent Application Laid-Open No. 8-273296, an ID (Identifier) is added to each frame of compression-encoded image data, and the ID and the recording position of the frame on the recording medium are determined. By associating the relationship, the position on the recording medium of the frame to be accessed at the time of trick play can be easily specified.

However, the former access means cannot be applied at all when the frame size of the compression-encoded image data does not have a fixed length, and the latter access means uses a frame ID and frame recording. It was necessary to separately create a table for associating the position with the position.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and efficiently reproduces specific image data during N-times speed reproduction of a disk on which compression-encoded image data is recorded. It is an object of the present invention to provide an image data recording device, a recording method, and a reproducing method that enable access.

[0008]

SUMMARY OF THE INVENTION An image data recording apparatus and method according to the present invention is directed to a method for recording image data on a disk by dividing the image data for each access unit of the disk. Then, an index for accessing an access unit in which specific image data is recorded is added and recorded for each access unit.

[0009] The image data reproducing method according to the present invention is directed to a method for reproducing the above-mentioned disc at N times speed. Then, an index is read from the disc at every predetermined number of access units set according to the double speed, and each time the index is read, the recording position of the access unit at which specific image data is recorded based on the read index is read. Is detected, and the recorded data is read from the detected access unit.

According to the above-described configuration and method, when recording image data on a disk, an access unit in which specific image data is recorded is accessed from the access unit for each access unit. Is recorded, and at the time of N-times speed reproduction of the disc, an access unit in which specific image data is recorded is detected based on the index for each of the access units that are jump-reproduced according to the speed. Since the image data is read, only specific image data can be efficiently accessed without reading much useless data, which is sufficiently suitable for practical use.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 (a)
2 shows image data recorded on a hard disk by a hard disk drive HDD. This image data is compression-encoded in accordance with the MPEG standard, and one I picture is followed by one P (Predictive)
A picture and four B (Bidirectionally predictive) pictures are arranged in a predetermined order.
One GOP (Group of Picture).

[0012] This image data is divided into 255 bytes, and is sequentially recorded in each sector of the hard disk in 256 byte units with a 1-byte index added to each head. This sector is assigned a continuous sector number, and serves as an address for accessing image data from the hard disk. That is, the sector is an access unit of the image data. Further, the example shown in FIG. 1A shows a case where image data for 6 pictures is recorded in 8 sectors.

When this image data is recorded on the hard disk, "ff (hexadecimal)" is recorded in each sector as an index until an I picture is detected, and the sector in which the I picture starts is recorded in the sector. “00” is recorded as an index, and a value that is sequentially incremented as an index is recorded in each of the subsequent sectors.
Record until a picture is detected.

When the index becomes "ff" due to the increment, "ff" is continuously recorded in the subsequent sectors until the next I picture is detected as the index.

That is, the fact that the index is "ff" means that the sector where the I picture starts is 255 or more sectors before the sector or that the I picture does not exist before the sector. are doing.

By the above-described index recording operation,
In the example shown in FIG. 1A, "ff" is recorded in the index up to the sector of sector number 1, and the sector number 2
"00" is recorded as an index in the sector of sector No. 3, and the subsequent incremented values are recorded in the sectors of sector numbers 3 to 9 as the index, respectively. Is recorded.

FIG. 1 shows a case where a hard disk on which image data is recorded as described above is reproduced at 6 × speed.
This will be described with reference to FIG. As described above, since the data rate of the image data on the hard disk is 6 pictures / 8 sectors, when playing back at 6 × speed,
What is necessary is to search for the I picture in units of 8 sectors. That is, the start position of the I picture is detected every eight sectors,
The operation of reproducing the image data is repeated.

First, the data of the sector of sector number 0 is read from the hard disk, and the value of the index is detected. In this case, since the index is “ff” and the current sector is the first sector, it is known that no I picture exists before this sector.

Next, the data of the sector with the sector number 8 after 8 sectors is read, and the index value is detected. In this case, since the index is "06", data is read from a sector having a sector number of 2 which is a value obtained by subtracting the index value "06" from the current sector number 8, and the image data of the I picture is read here. Will be played back.

Thus, the end position of the I picture,
That is, when the data reading from the sector with the sector number 4 is completed, the data of the sector with the sector number 16 which is 8 sectors later than the sector with the sector number 8 is read, and the value of the index is detected. . In this case, since the index is “06”, the value 1 obtained by subtracting the index value “06” from the current sector number 16 is 1
Data is read from a sector having a sector number of 0, and the image data of the next I picture is read and reproduced. Then, the above operation is performed for sector number 2
By performing the above operations repeatedly on sectors 4, 32, 40,..., 6 × speed reproduction is performed.

If the hard disk is to be played back at triple speed, as shown in FIG. 1 (c), each of the sectors having sector numbers 0, 4, 8, 12,... The operation of sequentially calculating the number of the sector at which the picture starts and reproducing the image data of the I picture is repeated.

However, in the case where the same I picture is continuously reproduced due to a low double speed number [in the example shown in FIG. 1C, the sectors with sector numbers 2, 3 and 4 are reproduced twice. In this case, an unnecessary access operation can be reduced by sending an instruction to the control system (display system) to display the same image as the previous image.

According to the above-described embodiment, when recording the compressed and encoded image data on the hard disk, each sector is provided with an index capable of calculating the number of the sector at which the I picture starts from that sector. At the time of N-times speed reproduction of the hard disk, the number of the sector at which the I picture is started is calculated based on the index for each of the sectors that are jump-reproduced at a predetermined number according to the speed speed. Since the image data of the I picture is reproduced, only the I picture can be accessed efficiently without reading much useless data, which is sufficiently suitable for practical use.

When no index is recorded in each sector, as shown in FIG. 1D, all data is read in order from the first sector, and only the image data of the I picture is reproduced. Since I-pictures are simply searched from sectors that are skipped and reproduced every predetermined number in accordance with the double speed, the efficiency is low.

Next, another embodiment of the present invention will be described with reference to FIGS. First, in FIG. 2A, the compression-encoded image data is divided into access units having a fixed data amount and recorded on a disk-shaped recording medium. At the head of each access unit, an absolute address n of the access unit including the start position of the I picture is recorded as an index.

As described above, the absolute address n of the access unit including the start position of the I picture is recorded as an index added to each access unit.
By reading the index from the randomly accessed access unit, it becomes possible to quickly reproduce an I picture located at a position close to the access unit while minimizing useless reading.

In FIG. 2B, at the head of each access unit, a relative address indicating the order of the access unit including the start position of the I picture counted from its own access unit is used as an index. Has been recorded. In this case, the negative and positive signs of the relative address are
It indicates that the access unit including the start position of the I picture is located after and before the access unit in the absolute address order.

As described above, since the relative address of the access unit including the start position of the I picture is recorded as the index added to each access unit, the index is read from the randomly accessed access unit. It becomes possible to quickly reproduce an I picture located at a position close to the access unit while minimizing useless reading.

Further, in FIG. 2 (c), at the head of each access unit, a relative address indicating the order of the access unit including the start position of the I picture, counting from its own access unit, is used as an index. Has been recorded. In this case, as the relative address, only the access unit including the start position of the I picture, which exists before the access unit in the absolute address order, is shown.
This is substantially the same as the example described with reference to FIG.

As described above, since the relative address of the access unit including the start position of the I picture is recorded as the index added to each access unit, the index is read from the randomly accessed access unit. It becomes possible to quickly reproduce an I picture located at a position close to the access unit while minimizing useless reading.

Also, since only the access unit including the start position of the I picture which is present before the predetermined access unit in absolute address order is indicated as the relative address, it is easy to generate the index at the time of recording. Becomes That is, one counter is prepared and cleared to 0 when an access unit including the start position of an I-picture is detected, and thereafter, the counter is incremented each time data writing shifts to the next access unit. An index can be generated.

Next, still another embodiment of the present invention will be described with reference to FIGS. First, in FIG. 3A, compression-encoded image data is recorded on a hard disk by being divided into sector units, which are physical access units at the time of data access. At the head of each sector, the start address of the sector including the start position of the I picture is recorded as an index.

This is effective when a system that manages data recorded on a hard disk in physical access units searches for a sector including the start position of an I picture.

As shown in FIG. 3B, on the hard disk, a plurality of continuous (4 in FIG.
) Are grouped as a cluster unit, which is a logical access unit at the time of data access. At the head of the first sector constituting each cluster, an address for reaching the cluster including the start position of the I picture is recorded as an index.

This is effective when a system that manages data recorded on a hard disk in units of logical access searches for a cluster including the start position of an I picture.

Further, as shown in FIG. 3 (c), a first index indicating an address for arriving at the cluster including the start position of the I picture is provided at the head of the first sector constituting each cluster. A second indicating the start address of the sector including the start position of the I picture in the cluster
Index and can be recorded.

As shown in FIG. 3D, a first index indicating an address for arriving at the cluster including the start position of the I picture is provided at the head of the first sector constituting each cluster. A second index indicating the start address of the byte including the start position of the I picture in the cluster can be recorded.

Here, in each of the above embodiments, information indicating the start position of an I picture is recorded as an index. However, the present invention is not limited to this. For example, information indicating the start position of a sequence header may be used. Good thing.
In this way, since the data is reproduced from the sequence header at the time of random access, it is possible to cope with a stream in which the image format of the encoded data changes dynamically.

It should be noted that the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the scope of the invention.

[0040]

As described in detail above, according to the present invention,
N of the disk on which the compression-encoded image data is recorded
It is possible to provide an image data recording device, a recording method, and a reproduction method that enable specific image data to be efficiently accessed during double-speed reproduction.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of the present invention;

FIG. 2 is a view shown for explaining another embodiment of the present invention;

FIG. 3 is a view for explaining still another embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/92

Claims (8)

[Claims] 1. An image data recording apparatus which divides image data on a disk for each access unit of the disk and records the divided data, for accessing an access unit on which specific image data is recorded for each access unit. An image data recording apparatus comprising: recording means for adding and recording an index. 2. An image data recording method in which image data is divided and recorded on a disk for each access unit of the disk, wherein an access unit in which specific image data is recorded is accessed for each access unit. An image data recording method characterized by adding an index of (1) and recording. 3. The image data recording method according to claim 2, wherein the index indicates a recording start position of an access unit where specific image data is recorded, by an absolute address or a relative address. 4. The recording apparatus according to claim 1, wherein the index indicates, by a relative address, a recording start position of an access unit in which specific image data is recorded before the index in an absolute address order when viewed from a predetermined access unit. 3. The image data recording method according to claim 2, wherein: 5. The access unit includes a first access unit having a predetermined data amount, and a second access unit obtained by further dividing the first access unit into a plurality of units. The index includes a first index for accessing the first access unit, and a second index for accessing the first access unit.
3. The image data recording method according to claim 2, further comprising a second index for accessing said access unit. 6. The image data is data that is compression-encoded according to the MPEG standard, and the specific image data is data corresponding to an intra-frame encoded image or a sequence header. 6. The image data recording method according to claim 2, wherein: 7. An apparatus according to claim 1, wherein the image data is divided and recorded for each access unit. For each access unit, a disc on which an index for accessing an access unit in which specific image data is recorded is recorded. In the image data reproducing method for reproducing at N times speed, the index is read from the disc at every predetermined number of access units set according to the speed, and every time the index is read, the identification is performed based on the read index. Detecting a recording position of an access unit in which the image data is recorded, and reading the recorded data from the detected access unit. 8. An access unit detected by an index read from a predetermined access unit during N-times speed reproduction is the same as an access unit detected based on an index of an access unit read before the predetermined access unit. 8. The image data reproducing method according to claim 7, wherein information indicating that the image data is the same as the previous image data is output.