Dynamic information storage or retrieval – Storage medium structure – Optical track structure
Reexamination Certificate
1998-10-14
2001-07-17
Edun, Muhammad (Department: 2753)
Dynamic information storage or retrieval
Storage medium structure
Optical track structure
C369S053130, C369S059160
Reexamination Certificate
active
06262965
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical disk in which data are recorded by using a file structure which is hierarchized like frames, packets, and packs and, more particularly, to that capable of reducing the burden on hardware.
BACKGROUND OF THE INVENTION
As optical disks for recording and reproduction of music information including speech or video information and reproduction apparatus, a CD (Compact Disk) and an LD (Laser Disk) are well known.
A CD is an optical disk having a diameter of 12 cm, in which music information is digitally recorded using a coding technique called “linear PCM”, and it has been used as an application recording medium for music. An LD is an optical disk having a diameter of 30 cm, in which video information with audio is recorded as analog signals, and it has been used as an application recording medium for video like a movie.
In recent years, in order to secure long-time recording and sufficient quality, there has been proposed an optical disk of about 12 cm in diameter, in which one or both of music information including speech and video information is/are digitally compressed and recorded with efficiency and, furthermore, having a file structure which facilitates data exchange with computers or communications.
FIGS.
5
(
a
) to
5
(
c
) are diagrams schematically illustrating the standard of a format when MPEG (Motion Picture Expert Group) data are recorded in a DVD (Digital Video Disk) which has been examined for practical use under the circumstances described above. In this format, data are recorded in units of packets as shown in FIG.
5
(
c
), and some of the packets are managed together using information called a pack header.
Further, each of the packets is composed of information called a packet header which indicates the attribute of the packet, and data composed of plural frames. In the packet header, identification information such as “videoe” or “audio”, control information, etc. are recorded.
When the medium (DVD) in which data are recorded as described above is reproduced using a reproduction apparatus, the reproduction apparatus is constructed so that an optical head irradiates the disk with a light beam and reads the recorded data as a change in reflectance of a light spot.
A description is given of a method for storing data in the medium having the structure described above.
As shown in FIG.
5
(
b
), each pack comprises a plurality of packets, and generally the same contents (e.g., video data or audio data) are assigned to each packet. Now, the case of audio using a coding method called MPEG is considered. As shown in FIG.
5
(
b
), when two packs which are adjacent each other with respect to the same contents (in this case, audio using the MPEG coding) are extracted, there arises a case where one packet is recorded over the two packs. In this case, it is necessary to divide the packet into two packets and insert a pack header or a packet header between the two packets, and this results in complicated authoring. Further, when retrieval or jumping has been carried out, data cannot be always reproduced from the beginning of the pack.
As shown in FIG.
5
(
a
), when the packs are recorded by one-to-one correspondence with sectors which are physical units for data management in the recording medium and include address information at their beginnings, access is facilitated in an application such as a DVD. However, this feature cannot be satisfactorily utilized because of the above-described problem.
As described above, in the conventional optical disk, there arises a case where data of one packet to be recorded is stored over adjacent two packs. On the other hand, with respect to such a multimedia optical disk, the following demands are made: to retrieve object audio information or video information as quickly and easily as possible; to secure synchronization between audio information and video information relating to the audio information; and to facilitate authoring when data above is interleaved on one track of the optical disk using the pack and packet structure.
In the optical disk having the above-described data structure, however, the following process steps are required for data reproduction: searching for a packet header for identifying frames, analyzing the information described in the packet header, searching for a frame synchronization signal (hereinafter referred to as a frame sync signal), and detecting it. These process steps make the speedy data search and simple authoring difficult. Further, when the reproduction apparatus is not provided with a data decoding function, it is general that data are output to the digital interface in frame units for decoding in an external decoder (e.g., IEC958 standard). In this case, each frame is output by detecting a frame sync signal which corresponds to the deepest layer in the hierarchical structure, and this causes the burden to the hardware.
SUMMARY OF THE INVENTION
The present invention is made to solve the above-described problems and to provide an optical disk having the capability of performing speedy accessing, securing synchronization between audio information and video information, and realizing simple authoring and easy extraction of data in a reproduction apparatus.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.
According to a first aspect of the present invention, there is provided an optical disk in which data are recorded by using a hierarchical file structure in which a frame is composed of digitized data, a packet is composed of at least one frame, and a pack is composed of at least one packet. In this optical disk, the pack is composed of an integral number of packets, each packet being completed, and each of the packets is composed of an integral number of frames, each frame being completed. Therefore, there is no possibility that one frame is assigned over two or more different packets and one packet is assigned over two or more different packs. Since an integral number of frames are assigned in each packet, when a packet header is detected, reproduction of data can be carried out from the beginning of each packet.
According to a second aspect of the present invention, in the above-described optical disk, each of the packets comprises one of the frames. As time information for synchronization is always given at the beginning of each frame in the packet, synchronization is easily made when data is reproduced, and highly precise synchronization is secured.
According to a third aspect of the present invention, in the above-described optical disk, the pack comprises one of the packets. Since only one packet header is included in each pack when data is reproduced, the redundancy is decreased as compared with the case where a plurality of packets are included in each pack.
According to a fourth aspect of the present invention, in the optical disk according to the second aspect, when the pack includes a plurality of packets, the data sizes of the packets, each including data of video information or audio information to be reproduced and a header of the packet, are made uniform by equally dividing a data area of the pack excluding the header area of the pack. Since the packet data size is fixed and known in advance, authoring is easily carried out, and the burden on a reproduction apparatus is reduced.
According to a fifth aspect of the present invention, in the optical disk according to the third aspect, when the packet includes a plurality of frames, the frame data sizes of all the frames, each including a frame sync signal, are made uniform by equally dividing the data area of the packet excluding the header areas of the pack and the packet. Since the frame data size is fixed and known in advance, authoring is easily carried out, and t
Kawamura Akihisa
Mori Yoshihiro
Shimbo Masatoshi
Suzuki Ryoji
Burr & Brown
Edun Muhammad
Matsushita Electric - Industrial Co., Ltd.
LandOfFree
Optical disk does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical disk, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical disk will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2524605