Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-03-31
2001-09-25
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06295409
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a video disk apparatus for writing/reading digital continuous data and specifically, digital video data and, more particularly, to a disk apparatus having the function of time-divisionally and alternately writing and reading digital video images on a plurality of channels.
A video disk apparatus for writing/reading digital video data on/from a storage medium such as an optical disk by using a digital video compression technique represented by MPEG is under development.
According to a conventional video disk apparatus using an optical disk, the digital video data compressed by an MPEG encoder serving as a digital video compressor or digital video data transmitted from a broadcast station, a CATV (cable TV), or the like is temporarily stored in a buffer memory at a predetermined bit rate. This buffer memory is used for adjusting the difference between the bit rate of input digital video data (the number of bits transmitted per second) and the write/read speed of an optical disk (the number of bits which can be written/read per second). In general, the bit rate of input digital video data is lower than the write/read speed of the optical disk.
Digital video data is written in the optical disk as follows. The digital video data is read out from the buffer memory at the write speed of the optical disk first. The data is then modulated into a signal suited for a write by a modulator/demodulator section. The signal is input to the optical head. The digital video data is written in the optical disk by this optical head.
Digital video data is read from the optical disk as follows. The optical head is moved to a radial position, on the optical disk, in which the digital video data of a desired video image is written. The digital video data is then read from the optical disk by the optical head. The read digital video data undergoes demodulation which is a reverse process to that in the write operation. The resultant data is input to the buffer memory. The data is sent from this buffer memory to an MPEG decoder serving as a digital video decompressor at the bit rate of the digital video data to be decompressed. The decompressed video data is input to a monitor to be displayed as a video image.
As, for example, the number of channels to be distributed increases, demands have arisen for the use of such a video disk apparatus, as one of usage patterns, in writing video images on a plurality of channels in the same time zone. The above conventional video disk apparatus, however, can write only one-channel digital video data at once. To write digital video data on a plurality of channels at once, a plurality of video disk apparatuses must be prepared. As a result, the user must bear a high cost and ensure an installation space.
Analog video recording/reproduction apparatuses capable of writing two-channel video images at once are commercially available. In such a conventional analog video recording/reproduction apparatus, however, the recording band per video image must be reduced, and hence a deterioration in image quality is inevitable.
As described above, according to the conventional techniques, a plurality of video disk apparatuses must be prepared to write video,images on a plurality of. channels in the same time zone. As a result, the user must bear a high cost and ensure a large installation space. When two-channel video images are to be written at once by an analog video recording/reproduction apparatus, since the recording band per video image is reduced, the image quality deteriorates.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a single disk apparatus which can simultaneously write digital video data such as digital video images on a plurality of channels without any deterioration in image quality.
According to the present invention, there is provided a disk apparatus for alternately and time-divisionally writing digital video data on a plurality of channels in a plurality of recording areas at different radial positions on a disk-like recording medium such as an optical disk through a buffer memory by using the difference between the write speed of the recording medium and the bit rate of continuous data such as digital video data.
According to the present invention, there is provided a disk apparatus comprising a head unit for writing digital continuous data on a disk-like recording medium, a buffer memory for temporarily storing a plurality of input digital continuous data, and a control section for performing control to time-divisionally write the plurality of digital continuous data in a plurality of different recording areas at different radial positions on the recording medium, wherein the control section writes, while one type of data of the digital continuous data is written and the head unit is accessing between the recording areas, another type of input data of the digital continuous data in the buffer memory, writes, in the buffer memory, one type of data of the digital continuous data input while another type of data of the digital continuous data is written and the head unit is accessing between the recording areas, reads out digital continuous data from the buffer memory and writes the data in a corresponding one of the recording areas at a write speed not less than two times an average bit rate of the input digital continuous data while another type of data of the digital continuous data is written, and reads out digital continuous data from the buffer memory at a write speed not less than two times an average bit rate of the input digital continuous data and writes the data in a corresponding one of the recording areas while one type of data of the digital continuous data is written in the recording area.
According to the present invention, a video disk apparatus for writing/reading digital continuous data such as digital video data on/from a disk-like recording medium by using a write/read head includes first and second buffer memories for temporarily storing first and second input digital continuous data, respectively, and a control section for time-divisionally and alternately writing the first and second digital continuous data in first and second recording areas at different radial positions on the recording medium, respectively.
In this case, the control section performs the following control:
(a) writing, in the first buffer memory, the first digital continuous data which is input while the second digital continuous data is written and the write/read head is accessing between the first and second recording areas;
(b) writing, in the second buffer memory, the second digital continuous data which is input while the first digital continuous data is written and the write/read head is accessing between the first and second recording areas;
(c) reading out, in writing the first digital continuous data, the digital continuous data stored in the first buffer memory at a write speed two times or more the average bit rate of the first input digital continuous data, and writing the data in the first recording area; and
(d) reading out, in writing the second digital continuous data, the digital continuous data stored in the second buffer memory at a write speed two times or more the average bit rate of the second input digital continuous data, and writing the data in the second recording area.
The write speed for the first digital continuous data is set to (T1+T2+2S)*A/T1 bps or more, and the write speed for the second digital continuous data is set to (T1+T2+2S)*A/T2 bps or more when the average write time per write of the first digital continuous data is T1 sec in time-divisionally and alternately writing the first and second digital continuous data in the first and second recording areas, the average write time per write of the second digital continuous data is T2 sec, the maximum access time (a time obtained by adding the time required for one revolution of the recording medium to the seek time required for the head unit to move from the innermos
Chevalier Robert
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
LandOfFree
Disk apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disk apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disk apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541698