Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1997-05-30
2001-03-06
Tran, Thai (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06198876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data recording/reproducing apparatus in which plural disc-shaped recording/reproducing means are run in parallel for increasing redundancy and reliability for assuring high processing speed and a large storage capacity.
2. Description of the Related Art
Recently, in an AV editing system configured for editing audio and video (AV) data and sending out the edited AV data, a disc array device, comprised of parallel connection of plural disc-shaped recording/reproducing means, such as magneto-optical disc drive or hard disc drive, has come into use for improving the recording capacity for recording the AV data and for improving the data transfer rate.
The disc array device uses plural disc-shaped recording/reproducing means, such as magneto-optical disc drive or hard disc drive, for improving the redundancy and reliability. In addition, the data transfer rate is increased for recording/reproducing digital data, such as video or audio data.
The disc array device is classified into five levels of RAID (Redundant Arrays of Inexpensive Discs)
1
to RAID
5
, depending on characteristics, such as accommodation to reliability, interleaving, storage of error correction code and management.
In general, the digital data, such as video or audio data, is larger than computer data in size of data accessible at a time. Thus, for the disc array device handling the AV data, the RAID
3
type is used, in which AV data are striped on the bit or byte basis for reading or writing from or to plural hard disc drives in unison and in which a hard disc for reading or writing data is fixed.
FIG. 1
shows the constitution of a disc array device
60
handling such AV data. This disc array device
60
can handle plural disc drives (HDDs) as if these disc drives were a sole recording/reproducing means. For example, the AV data, divided into 16 portions (0, 1, 2, . . . , 15) are assorted and recorded via a disc array controller
62
in HDDs
611
,
612
, . . . ,
618
, at the same time as the AV data portions are coupled to a HDD
61
P configured for recording only parity P
1
, P
2
, . . . calculated from these AV data. This raises the redundancy while assuring the reliability. Since a parity HDD
61
P is associated with eight HDDs for data HDD
611
, HDD
612
, . . . , HDD
618
, the transfer rate is ideally 192 Mbps if the transfer rate per each HDD is 24 Mbps.
It is assumed that an AV editing system as shown in
FIG. 2
is constituted using such disc array device
60
. If an AV editing controller
65
for editing AV data and the disc array device
60
are connected to each other by small computer system interfaces (SCSIs)
66
,
67
, which are customary interfaces, for constituting an AV editing system, the minimum unit of data accessible at a time, that is the size of the write/readout unit (sector unit) of the disc array device
60
, is as shown in FIG.
3
. If the 512×8=4096 bytes. If the write/readout unit (sector unit) per HDD is 512 bytes, as an example, the size of the write/readout unit of the disc array device is 512×8=4096 bytes.
Assuming that data handled is the AV data of the D
2
standard, video data is made up of two frames compressed to approximately {fraction (1/7)}, and four channels of audio data are appended. Thus the transfer format is made up of 163840 bytes of video data followed by four channels each comprised of 8192 bytes of audio data, as shown in FIG.
4
.
In such transfer format, the size of the video data and that of the audio data are multiples of the size of the write/readout unit of 4096 bytes, indicated as blocks as shown in FIG.
5
. Thus the interruptions between the video data and the audio data or the interruptions between the audio data coincide with the interruptions of the write-readout units in the inside of the disc array device
60
.
Therefore, even in case of an editing operation of rewriting only image data or individually accessing audio data of each channel for data interchanging, data readout/writing is possible without any inconvenience, so that these functions can be realized without lowering the performance.
Recently, with improved performance of the HDD, it has become possible to maintain or improve the overall transfer rate or capacity even if the number of HDDs used for data in the inside of a sole disc array device is reduced.
On the other hand, if the number of HDDs in the inside of the disc array device is changed, the size of the writing/readout unit in the disc array device of the RAID
3
configuration is changed. If, for example, the number of the HDDs of the disc array device
60
shown in
FIG. 1
is reduced by one and a sole HDD for parity is allocated to the seven HDDs, the size of the write/readout unit of the disc array device is 512×7=3584 bytes, as shown in FIG.
6
.
Meanwhile, if an AV editing system shown in
FIG. 2
is constituted by the disc array device employing seven HDDs for data, the size of the write/readout unit of 3584 bytes of the disc array device is not al aliquot part of the AV data size of the transfer format, as a result of which the interruption of video data or audio data is not coincident with the interruption of the write/readout unit of 3584 bytes of the disc array device (shown as a block), as shown in FIG.
7
.
Thus, if video and audio data are contiguously recorded by the data transfer format shown in
FIG. 4
, but if video and audio data are desired to be reproduced or edited beginning from the interruption point of the video or audio data, it becomes necessary to invoke the entire blocks (write/readout units) containing the data interruption points and to reproduce only required portions or partially interchange recording data before proceeding to calculation of parity data for recording. In
FIG. 7
, blocks 46, 48, 50, 52 and 54 represent blocks containing data interruption points.
That is, for data reproduction, superfluous data not desired to be reproduced is read out during data reproduction. These superfluous data, thus read out, are not reproduced and hence need to be removed. For data recording, if the interruption point of video or audio data is not coincident with the junction point of the block (write/readout unit) of the disc array device, it becomes necessary to read out data of the entire block also containing unchanged data portions. In addition, although data only of the recording portion has been changed, parity data are updated along with unchanged data portions.
These operations lower the average transfer rate during editing or variable speed reproduction of the disc array device. The result is that an additional circuit is required for assuring data continuity essential for video and audio data or the apparatus is complicated in its entirety thus raising the cost. In addition, the editing system apparatus in its entirety cannot exhibit performance so that it cannot cope with multi-channel processing.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a data recording/reproducing apparatus whereby the transfer rate is prohibited from being lowered and the size of the input/output data can be matched to the data write/readout size while avoiding increased cost.
In one aspect, the present invention provides a data recording/reproducing apparatus including a plurality of disc-shaped recording/reproducing means in which the data size that can be accessed at a time can be controlled by changing the number of the recording/reproducing means loaded in position during data recording, and data adjustment means for appending padding data so that, if the volume of data for recording is not equal to a multiple of the data size accessed at a time, the volume of data for recording with the padding data appended thereto will equal to the multiple.
When data recorded with the padding data appended thereto are reproduced, the data adjustment means preferably manages control so that the padding data will not be reproduced.
Preferably, the recording data are
Iwasaki Yasuo
Ogura Makoto
Suzuki Shogo
Frommer William S.
Frommer Lawrence & Haug LLP.
Smid Dennis M.
Sony Corporation
Tran Thai
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