Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Patent
1997-04-10
1998-09-15
Chevalier, Robert
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
386125, H04N 5911, H04N 5781
Patent
active
058092064
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Field of the Industrial Application
The present invention relates to an information signal reproducing apparatus and an information signal reproducing method and is, in particular, suitably applied to an audio and/or video server system, for example.
2. Background Art
As an device for supplying video signal and audio signal to plural terminal devices respectively from one video and audio supplying source provided in the broadcasting station, an audio video server system (hereinafter referred to as an AV server system) has been proposed. For the construction of the AV server system, it is proposed that video signal and audio signal are stored in a media unit having plural built-in disk devices so as to transmit the selected video signal and audio signal from the media unit to terminal devices.
Such AV server systems, however, need to send out video signal continuously to each terminal device. The media unit of AV server system therefore reproduces video and audio signal from the disc recording medium in the disk device in order that the video signal having the fixed amount of data can be supplied constantly to each terminal device.
The disk device for reproducing video and audio signal from a disc recording medium will be described below. In this case a hard disk device is used as the disk device.
A hard disk device has such construction that a hard disk being a disc recording medium is rotated and the video and audio signal are recorded and reproduced on and from the hard disk by a recording and reproducing head. At this point, since normally there is only one recording and reproducing head, the recording and reproducing head accesses to the video and audio signal on the hard disk sequentially.
Furthermore, since the recording and reproducing head works mechanically, it takes longer access time when the access position of the recording and reproducing head is largely changed, i.e., in seek time, as compared with the case of accessing continuous positions. Moreover, after the recording and reproducing head moves, a certain time is required till the position where the selected video and audio signal are recorded reaches the position of the recording and reproducing head. It is called rotational latency time.
Here, constant supply of the fixed amount of data of video and audio signal to each terminal device, such as the above-mentioned disk device used in the AV server system, requires the capacity for continuous output of the video and audio signal with taking the total access time including seek time, rotational latency and output of data into account.
Moreover, the AV server system requires real time accessability because the data to be read out from the hard disk is video and audio signal. For example, if the reproduced video and audio signal is supplied continuously discontinued. Therefore, in order to supply the video and audio signal continuously to twelve terminal devices, it is necessary to reproduce hard disk.
Further, mechanical work of the hard disk device sometimes produces unexpected action even though the occurrence frequency is low. For example, when the video and audio signal is accessed by moving the head onto the fixed circular track of hard disk, there are cases where data cannot be read out correctly because of the head position shift caused by expansion and contraction of each member because of temperature and mechanical operation error. In this case, the hard disk device corrects the position of the recording and reproducing head and accesses again. Normally, in the course of repetition of these operations, the correct data can be read out.
Repeating these operations, however, makes rotational latency time specifically longer and access speed becomes low. Resultingly, at the time when the reproduction data is supplied to each channel, if a block of the fixed amount of data of video and audio signal that have to be read out in can cause problems with video and audio signal cut off because the block of the video and audio signal cannot catch up with the reproduction.
DIS
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Patterson, David A., Gibson, Garth, and Katz, Randy H., "A Case for Redundant Arrays of Inexpensive Disks (RAPID)", ACM SIGMOD Conference, Chicago, Illinois, Jun. 1-3, 1988, pp. 109-116.
Chevalier Robert
Frommer William S.
Sony Corporation
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