Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-03-18
2001-12-18
Tran, Thai (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06332058
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to an information reproduction apparatus and an information reproduction method for reading out an information material having a plurality of clips and reproducing the clips of the information material consecutively.
2. Prior Art
In recent years, the techniques of compression-coding image information and audio information with minimum deterioration and then decoding the compressed-coded information material with a reproducing means have been developed. For example, the MPEG (Motion Picture Experts Group) system standard has been proposed as a scheme for compression-coding and then decoding (expanding) image information and audio information. An audio-video material or the like that has been compressed and multiplexed according to the MPEG system standard consists of a plurality of clips as shown in FIG.
12
. Each clip consists of a plurality of clusters, four clusters in the example of
FIG. 12. A
“cluster” is a unit that is an integral multiple of a unit (for instance, 512 bytes) that is formed on a hard disk (HDD) and generally called a sector. The example of
FIG. 12
shows two clips, i.e., a certain clip CP
2
and a preceding clip CP
1
.
In the conventional example of
FIG. 12
, an information material (MPEG stream)
2
having clips CP
1
, CP
2
, etc. is recorded on a hard disk (HDD)
1
. The information material
2
recorded on the hard disk
1
is to be decoded by a decoder. However, direct access to the information material
2
cannot be effected between the hard disk
1
and the decoder
2
. This is because the MPEG stream is recorded on the hard disk
1
so as to be divided into certain units (for example, 4-byte units; hereinafter referred to as cells
1
a
) and a DMA buffer
3
needs to be used as a buffer for absorbing a size difference between the cell
1
a
of the hard disk
1
and the cluster CT. That is, in accessing the hard disk
1
, the information material
2
needs to be temporarily stored in a buffer
3
A or a buffer
3
B.
To decode the clusters of the clips CP
1
and CP
2
, for instance, by sending those to decoders
4
a
and
4
b
consecutively, a switcher
5
is used as shown in FIG.
12
. The first cluster CT
1
of the preceding clip CP
1
is stored in the buffer
3
A and reproduced by a decoder
4
a
, and the next cluster CT
2
is stored in the buffer
3
B and decoded by the decoder
4
b
. The switcher
5
sequentially outputs the clusters CT as a video signal, an audio signal, or the like by switching between the decoders
4
a
and
4
b
. As the switcher
5
switches between the decoders
4
a
and
4
b
, the clusters CT of the preceding clip CP
1
and the clusters CT of the (ensuing) clip CP
2
are reproduced consecutively.
However, the above method requires two channels, i.e., a channel CH
1
consisting of one buffer
3
A and one decoder
4
a
and a channel CH
2
consisting of another set, i.e., the buffer
3
B and the decoder
4
b
. That is, the decoders
4
a
and
4
b
of two channels need to be prepared.
There may be conceived a somewhat improved scheme in which a decoder of one channel is prepared and the transfer of the information material
2
from the hard disk
1
is given the ability of two channels. However, in either scheme, the transfer ability resources of two channels are necessarily required for the reproduction of the information material
2
on the hard disk of one channel, resulting in a cost increase.
In view of the above, there has been proposed a scheme for consecutively reproducing a plurality of clips CP
1
and CP
2
as shown in
FIG. 12
by using resources of less than two channels. This scheme is disclosed in Japanese Unexamined Patent Publication No. Hei. 8-289255. The technique disclosed in this publication employs a scheme in which in a state that there exist a certain clip CP
2
and the preceding clip CP
1
as shown in
FIG. 12
, their sizes are adjusted so as to be equal to an integral multiple of the cluster size.
For example, where there exists invalid data DD (called dust data) as at least part of the fourth, i.e., last, cluster CT
4
of the clip CP
1
, the following problem arises. For example, when the decoder
4
b
decodes the last cluster CT
4
including the invalid data DD coming from the buffer
3
B, only effective data t excluding the invalid data DD is actually readout. If the time necessary to readout the effective data t is, for instance, 0.1 second, an operation of sending the cluster CT
4
of the clip CP
1
from the buffer
3
B to the decoder
4
b
is performed for 0.1 second. At the same time that the cluster CT
4
is being read from the buffer
3
B, an operation of reading out the head cluster CT
1
of the clip CP
2
from the hard disk
1
and supplying it to the buffer
3
A is performed. At this time, the time required for reading out the last cluster CT
4
and supplying it to the decoder
4
b
is equal to the 0.1 second that it takes to readout the effective data t and supply it to the decoder
4
b
, and hence information, corresponding to only 0.1 second, of the head cluster CT
1
of the clip CP
2
can actually be readout. Therefore, if the time necessary to readout the head cluster CT
1
of the clip CP
2
and supply it to the buffer
3
A is 1 second, only part of the information material
2
, corresponding to only 0.1 second, can be readout from the hard disk
1
and supplied to the buffer
3
A.
To avoid the above inconvenience, a special, dedicated encoder is necessary which codes a certain clip CP
2
and the preceding clip CP
1
so as to produce data having completely the same size even if there exists invalid data DD.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and an object of the invention is therefore to provide an information reproduction apparatus and an information reproduction method which can consecutively reproduce a plurality of clips of an information material without the need for preparing resources of two channels and without using a special, dedicated encoder.
According to the invention, the above object is attained by an information reproduction apparatus for reading out an information material having a plurality of clips and consecutively reproducing the clips of the information material, comprising a recording medium on which an information material having a plurality of clips is recorded, information material storing means, including temporary buffer means, for reading out, upon request and in sequence, a first clip and a second clip of the information material that each consist of a plurality of clusters from the recording medium, and writing the readout clips to the temporary buffer means, write finish flag generating means for setting a write finish flag at a time point when writing of a cluster of the second clip from the recording medium to the temporary buffer means by the information material storing means is finished, information material reproducing means for reproducing the first clip from the temporary buffer means at the same time that the second clip is being written in the temporary buffer means by the information material storing means, and including means for detecting the setting of the write finish flag and pausing reproduction of the first clip until the write finish flag is detected as having been set, so that even in a case where at least part of a last cluster of the first clip is invalid data all of the second clip will be written to the temporary buffer means.
With the above configuration, even if at least part of or all of the last cluster of the preceding clip is invalid data, the information material reproducing means can continue to reproduce the last cluster including the invalid data until setting of the write finish flag. As a result, the time taken to readout a cluster of a certain clip from the recording media and supply it to the information material storing means can be equalized to the time taken to reproduce a cluster of the preceding clip from the information material storing means to the information
Crosby, Heafey Roach & May
Shaw Philip M.
Sony Corporation
Tran Thai
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