HK1022979B - Method of reproducing image data - Google Patents

Description

Image data reproducing method

Technical Field

The present invention relates to an optical disc on which compressed data of an image is recorded, and to an optical disc reproducing apparatus for reproducing image data from an optical disc.

Background

The so-called "CD-ROM" is a typical example of those systems that use optical discs for the playback of digital data. The CD-ROM records data for a computer on an optical disk having the same physical format as a CD for audio use, the data format of which is described below. The data string recorded on the optical disc is composed of minimum units called "frames", each of which contains digital data such as sync data, subcodes, main information, and error correction codes.

In addition, CD-ROMs employ a sector structure. Where 98 frames (2, 352 bytes) are grouped in a sector, each sector including 12 bytes of synchronization data, 4 bytes of header data indicating an address and a pattern, 2,048 bytes of digital data, and 288 bytes of error detection/correction codes.

On the other hand, a system including a combination of inter-frame prediction and orthogonal transformation, quantization, and variable length coding is called a coding system of moving pictures, and the MPEG system of ISO (international organization for standardization) is also based on such a system. In the case of MPEG2, for example, a bitstream of encoded image data is divided into six layers, i.e., a sequence layer, a GOP (group of pictures) layer, a picture layer, a slice layer, a macroblock layer, and a block layer. Among these layers, the GOP layer contains three types of data, i.e., I pictures like those encoded based on information without using inter prediction, P pictures generated by prediction based on I pictures or P pictures, and B pictures generated by bi-directional prediction. The progressive layers include a GOP containing picture data obtained by grouping I pictures, P pictures, and B pictures into a group from the beginning of the I picture, and SH (progressive header) added to the leading part of the GOP.

When converting moving images into compressed image data by efficient coding, a system is known for coding a signal by reducing the compression ratio, in other words at a high transmission rate, for scenes with active motion, and increasing the compression ratio, in other words at a low transmission rate, for scenes with little motion. The variable transfer rate compressed image data thus encoded can reduce the deterioration of the image due to compression as compared with the fixed transfer rate compressed image data obtained at the average fixed compression ratio.

There has been announced an apparatus for recording and reproducing compressed image data having a variable transfer rate or a fixed transfer rate onto an optical disk such as a CD-ROM.

The above-mentioned prior art does not specifically consider so-called "trick play" (trick play) such as n-speed variable speed playback or reverse playback with respect to the normal speed playback of the picture data recorded on the optical disc. In reproducing image data, in addition to continuous reproduction at a standard speed, for example, variable speed reproduction at n-times speed or reverse reproduction is generally required, and a reproducing apparatus satisfying these requirements is necessary. The retrieval operation also requires high-speed retrieval.

Disclosure of Invention

An object of the present invention is to provide an optical disk and an optical disk reproducing apparatus which are capable of performing various kinds of trick play operations on an optical disk on which compressed image data is recorded and capable of performing a high-speed search operation.

To accomplish the above object, an optical disc according to the present invention records specific information required for trick play in an arbitrary area of the optical disc, such as a TOC (table of contents) or a leading sector (sector 0), and adds a sector address to each sector.

An optical disk reproducing apparatus according to the present invention includes means for extracting and reproducing I pictures, P pictures, and B pictures contained in GOP layers within a bit stream of compressed picture data by referring to a trick play table.

After the optical disc is loaded into the optical disc reproducing apparatus, the system microcomputer first reads the trick play table recorded on the optical disc and stores it in the work area. When trick replay is performed, the address of a sector to be read out is determined by referring to a necessary trick play table, and the address is retrieved on the optical disk to reproduce a picture.

Since the address of the sector to be read out is determined by referring to the trick play table during trick play other than normal playback, trick play can be performed easily and retrieval playback images can be obtained quickly in the retrieval operation.

Drawings

Fig. 1 is a schematic diagram showing a first embodiment of an optical disc according to the present invention;

fig. 2 is a schematic diagram showing a second embodiment of an optical disc according to the present invention;

fig. 3 is a schematic diagram showing a third embodiment of an optical disc according to the present invention;

fig. 4 is a schematic diagram showing a fourth embodiment of an optical disc according to the present invention;

fig. 5 is a schematic view showing an optical disc according to a fifth embodiment of the optical disc of the present invention;

fig. 6A and 6B are each a schematic diagram showing an optical disc according to a sixth embodiment of the present invention;

fig. 7 is a simplified diagram illustrating a data format of an optical disc according to a seventh embodiment of the present invention;

fig. 8 is a simplified diagram illustrating a data format of an optical disc according to an eighth embodiment of the present invention;

fig. 9 is a simplified diagram illustrating a data format of an optical disc according to a ninth embodiment of the present invention;

fig. 10 is a simplified diagram showing tracks on an optical disc according to the present invention: and

fig. 11 is a flowchart of the operation at the time of trick play.

Detailed Description

Some preferred embodiments of the invention are described below with reference to the accompanying drawings. The embodiment shown in figure 1 will first be described,

fig. 1 shows an optical disc according to a first embodiment of the present invention. This figure shows a trick play table on an optical disc. This trick play table records, for example, segment numbers (indexes) of motion and music and corresponding sector addresses of all segments of motion and music recorded on the optical disc. Sector addresses are added to the sectors of the disc, and this trick play table is recorded in an area of the disc such as the TOC (table of contents) or the leading sector (sector 0).

When the optical disk is loaded into the optical disk reproducing apparatus, the system microcomputer first reads out the trick play table and stores it in the work area. When trick play is performed, the address of a sector to be read out is determined by referring to this trick play table, and then the address of the sector is retrieved on the optical disk to play back the picture.

Since the address of the sector to be read out is determined by referring to the trick play table, high-speed detection is possible.

Fig. 2 shows an optical disc according to a second embodiment of the invention, this figure showing a trick play table on the optical disc. The trick play table records the sector address of the recorded data on the optical disc and the corresponding time code. This trick play table is recorded in an area of the optical disc such as the TOC (table of contents) or the leading sector (sector 0).

When the optical disk is loaded into the optical disk reproducing apparatus, the system microcomputer first reads out the trick play table and stores it in the work area. When trick play is performed, the address of the sector is read out by referring to the sheet and the trick play surface, and the address is retrieved on the optical disk to reproduce the picture.

Since the address of the sector to be read out is determined by referring to the trick play table during trick play other than normal playback, trick play can be performed easily and retrieval can be performed at high speed.

When compressed image data of variable transfer rate is reproduced, since there is no proportional relationship between the sector address and the time code, the sector address cannot be determined from the time code, and a correct search cannot be made. However, by referring to the trick play table of this embodiment, the corresponding sector address can be obtained, and the retrieval can be performed correctly.

Fig. 3 shows an optical disc according to a third embodiment of the present invention. This figure shows a trick play table on an optical disc. The trick play table records the addresses of all sectors of data recorded on the optical disc and the contents thereof. This trick play table is recorded in an area of the optical disc such as the TOC (target) or the leading sector (sector 0).

When an optical disk is loaded into an optical disk reproducing apparatus, a system microcomputer first reads out a trick play table and stores it in a work area, and when a search is made, an address of a sector to be read out is determined by referring to the trick play table, and this address is searched on the optical disk to reproduce an image.

Since the address of the sector to be read out is determined by referring to the trick play table during trick play other than normal playback, trick play can be performed easily and retrieval can be performed at high speed.

Fig. 4 shows an optical disc according to a fourth embodiment of the present invention. This figure shows a trick play table on an optical disc. The trick play table records SH (sequential header) and its sector address added to the leading part of the GOP recorded on the optical disc. This trick play table is recorded in an area such as the TOC (table of contents) or the leading sector (sector 0) of the optical disc.

When the optical disk is loaded into the optical disk reproducing apparatus, the system microcomputer first reads out the trick play table and stores it in the work area. When retrieval is performed, the address of the sector to be read out is determined by referring to the trick play table, and this address is retrieved on the optical disk to reproduce the picture.

Since the address of the sector to be read out is determined by referring to the trick play table during trick play other than normal playback, trick play can be performed easily and high-speed retrieval can be performed.

Fig. 5 shows an optical disc according to a fifth embodiment of the invention, which figure shows a trick play table on the optical disc. The trick play table records the addresses of sectors where the I picture recorded on the optical disc starts and ends. This trick play table is recorded in an area of the optical disc such as the TOC (table of contents) or the leading sector (sector 0).

When the optical disk is loaded into the optical disk reproducing apparatus, the system microcomputer first reads out the trick play table and stores it in the work area. When retrieval is performed, the address of the sector to be read out is determined by referring to the trick play table, and this address is retrieved on the optical disk to reproduce the picture.

Since the sector address of the I picture is determined by referring to the trick play table during trick play other than normal playback, trick play is performed by extracting only the I picture. The sector addresses of B picture and P picture can be recorded in the trick play table and the trick play can be smoothly performed.

Fig. 6A and 6B show an optical disc according to a sixth embodiment of the present invention. Fig. 6A schematically shows tracks on an optical disc. Fig. 6B schematically shows a plurality of trick play tables 1, 2, 3 and their identification codes T1, T2, T3 recorded on the track. When the optical disk is loaded into the optical disk reproducing apparatus, the system microcomputer reads out the trick play tables recorded on the optical disk and stores them in the work area. In this case, the system microcomputer can identify each trick play table by using the identification code, and can store the trick play table to a predetermined address of the work area. Therefore, even when any type of trick play table exists, the system microcomputer can recognize each trick play table and can store it in the work area. In other words, the system microcomputer can determine the sector address by referring to the necessary trick play table during the trick play, and can easily perform the trick play while performing the high-speed search.

Fig. 7 shows an optical disc according to a seventh embodiment of the present invention. Fig. 7 schematically shows a data format recorded on a track of an optical disc. Each sector is divided into blocks. These blocks contain synchronization signals (Sync), Sector Addresses (SA), Block Addresses (BA), parity (P), digital Data (Data) and Error Correction Codes (ECC). The same address is recorded for each block of sector addresses.

Fig. 8 shows an optical disc according to an eighth embodiment of the present invention. Fig. 8 schematically shows a data format recorded on a track of an optical disc. Each sector is further divided into blocks. These blocks contain synchronization signals (S0, S1), Sector Addresses (SA), Block Addresses (BA), parity (P), digital Data (Data), and Error Correction Codes (ECC). Sector addresses are recorded in two blocks, and SA1 and SA2 together represent one address. Therefore, compared with the seventh embodiment in which the same address is written for each block, the sector address can be written in every two blocks, the redundancy of the address is small, and the address area can be made smaller than that in the seventh embodiment.

Fig. 9 shows an optical disc according to a ninth embodiment of the present invention. Fig. 9 schematically shows a data format recorded on a track of an optical disc. Each sector is further divided into blocks. These blocks include synchronization signals (S0, S1, S2), Sector Addresses (SA), Block Addresses (BA), parity (P), digital Data (Data), and Error Correction Codes (ECC). Sector addresses are recorded in two blocks, and SA1, S2, and SA3 together represent one address. Therefore, the same address can be written in every two blocks. Accordingly, the address redundancy is small and the address area can be made smaller than in the seventh and eighth embodiments.

Fig. 10 schematically shows tracks on an optical disc, on which spiral tracks are formed. Symbols (X-1), X, (X +1) … …, (X + n), and (X + n +1) respectively denote sectors, and data is played back in this order during normal playback.

The trick play operation will be explained below as an operation when playing back at n times the playback speed. Assuming that a command for n-speed reproduction is input while sector X in fig. 10 is being reproduced, first, after reading out the data of sector X, the next target sector (X + n) is retrieved by track transfer or the like. The distance n from the start position to the target sector is calculated by the system microcomputer according to which multiple speed the playback is to be performed. After the search is performed in this way, the data of the sector (x + n) is read out, and the next sector (x +2n) is searched. This operation is repeated.

When an optical disk is loaded on an optical disk reproducing apparatus, a system microcomputer first reads out a trick play table recorded on the optical disk and stores it in a work area. When trick play is performed, the address of the sector to be read out is determined by referring to a necessary trick play table. The address is retrieved on the optical disc to reproduce the image.

Fig. 11 shows a flowchart of an operation in the above-described n-speed playback process. Where the symbol m denotes the frame (field) time interval of an I picture. When an instruction for reproducing at n-times speed is input from an external input device such as a remote controller, it is first determined whether or not the relation m-n is satisfied. When m is n, only the I picture is searched by using the trick play table for reproduction, and when m is less than n, the I picture is searched and reproduced by using the trick play table. When the result is 2 m-n, 3 m-n, etc., only the I picture is retrieved and played back. When P pictures are retrieved and skipped over in addition to I pictures at this time, reproduction at various speeds can be smoothly performed, and when the result is m > n, P pictures are retrieved and reproduced skipped over using a trick play table in addition to I pictures. At this time, when B pictures are detected and skipped in addition to I pictures and P pictures, reproduction at various speeds can be smoothly performed. Thereafter, if the playback at n times the speed continues, the above operation is repeated.

Although the above description relates to n times speed playback operation, the invention can also be applied to reverse playback, where n in n times speed playback is negative (-). In addition, slow playback can be performed when | n | < 1.

As described above, when retrieval is made by referring to the trick play table, for example, GOP unit image playback can be easily performed in image data encoded by the MPEG system. Trick play operations such as slow playback, fast playback, reverse playback, and high-speed retrieval operations can be performed in addition to the normal-speed continuous playback operation.

The present invention is not particularly limited to the above-described embodiments, but may be changed and modified in various ways without departing from the scope thereof.

In the optical disc according to the present invention, information necessary for trick play is recorded in an arbitrary area of the optical disc such as the TOC (table of contents) or the leading sector (sector 0), each sector being added with a sector address. An optical disk reproducing apparatus refers to a trick play table, extracts and reproduces I pictures, P pictures and B pictures contained in a GOP layer in a bit stream of compressed picture data. Therefore, the present invention can easily perform trick play such as slow playback, high-speed playback, reverse playback, and retrieval operation. It is apparent that in the above description, the image data may be a moving image or a still image.

In addition, it is shown that the present invention can be applied equally to audio data and control data carried by image data.

Claims (1)

1. A method of reproducing picture data recorded on an optical disc, said picture data being recorded in a plurality of sectors arranged on said optical disc, sector addresses being recorded in respective corresponding sectors, said picture data being at least compressed picture data having a variable transfer rate, said optical disc having a trick play table containing information relating to said sector addresses and a presentation time of said compressed picture data, a relationship between said sector addresses and said presentation time being non-fixed, said method comprising the steps of:

reading the trick play list recorded on the optical disc and storing the trick play list in a working area;

detecting a sector address of desired image data to be read out in association with a desired presentation time by referring to said trick play table in association with said sector address and said presentation time; and

the detected address on the optical disc is retrieved to reproduce the image.