Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-08-26
2002-09-24
Tran, Thai (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C375S240260, C370S394000, C370S517000
Reexamination Certificate
active
06456782
ABSTRACT:
TECHNICAL FIELD
The present invention relates a data processing apparatus and method and is suitably applied to a transmitter of a digital video broadcast (DVB) system, for example.
BACKGROUND ART
Heretofore, there is a MPEG2 (Moving Picture Experts Group Phase 2) as a method of compression-encoding video data and audio data. This MPEG2 scheme is standardized (for example, recommendation, H.222.0) by an association such as ITU-T (International Telecommunication Union-Telecommunication Standardization Sector), to compression-encode, multiplex, store, and transmit video data and audio data.
In actual, in this MPEG2 scheme, a data form referred to a program stream (PS) and a data form referred to a transport stream (TS) are standardized as a data form for multiplexing compression-encoded video data and compression-encoded audio data. In this connection, the PS data form is applied to the case of storing multiplexed video data and audio data in a predetermined digital storing medium, and the TS data form is applied to the case of transmitting multiplexed video data and audio data.
Here, for example, the TS data form is so standardized that compression-encoded video data and audio data are converted into packets (hereinafter this is referred to TS (transport stream) packets) every predetermined unit (for example, every 188-byte data), and each of the resultant TS packets is subjected to time division multiplexing to form a TS packet stream (that is, a transport stream).
Note that, as shown in
FIG. 17
, the TS packet
1
is composed of a header part and a data part, in which the header part stores a synchronization byte, a packet identification (hereinafter, this is referred to as a PID (packet identification)) and other kinds of packet control data and the data part stores compression-encoded video data or audio data. In this connection, the synchronization byte is data showing the beginning of the TS packet
1
, and the PID is data showing the content of information stored in the TS packet
1
.
However, in recent years, a digital video broadcast system has been considered to compression-encode and multiplex video data and audio data with the MPEG
2
scheme described above and then broadcast using a ground wave, a satellite wave, a cable, or the like. Such digital video broadcast system has been considered to be capable of broadcasting a plurality of television programs with one circuit by converting compression-encoded video data and audio data into TS packets and multiplexing them, as described above.
In actual, in a transmitter, for example, a transport stream is formed by forming TS packets at different timings with each encoder, and is supplied to a multiplexer. Thereby the multiplexer sequentially reads a plurality of TS packets included in the transport stream in an arrival order without overlap and moreover transmits them in the same order to perform multiplexing processing.
That is, normally, the multiplexer is composed of an input unit of being supplied with a transport stream from each encoder and a multiplexing unit for sequentially reading each transport stream from the input unit in a unit of TS packet included in the transport stream. For example, as shown in
FIG. 18
, the first TS packet corresponding to a television program for the first channel CH
1
is supplied so as to arrive at the input unit at timing of time “n” when the TS packet is formed (FIG.
18
A), and the second TS packet corresponding to a television program for the second channel CH
2
is supplied so as to arrive at the input unit at timing of time “n+c” when the second TS packet is formed, with keeping a packet interval Sets (FIG.
18
B).
Therefore, in the transmitter, the order in which the TS packet arrives at the multiplexing unit is the same as the order of TS packets included in the transport stream TS
1
formed by performing multiplexing with the multiplexing unit. In this connection, each of the TS packets included in the transport stream TS formed in the multiplexing unit delays by a processing time d required to the multiplexing processing of the multiplexing unit (FIG.
18
C).
In this way, the digital video broadcast system has been considered, in which TS packets corresponding to a desired channel out of the TS packets included in the transport stream TS
1
received as a transmission signal from a receiver are sequentially decoded in the receiving order, thereby making it possible to accurately reproduce video data and audio data corresponding to the TS packets.
However, in each encoder of the aforementioned digital video broadcast system, the processing time required to encoding processing and packetizing processing is varied depending on the amount of supplied video data and the amount of supplied audio data, and it takes a long time after the multiplexing unit reads a TS packet which arrives first until a TS packet which arrives next is supplied to the multiplexing unit. As a result, a delay time required to the multiplexing processing may not be fixed in the TS packets.
That is, in the multiplexer, such a case may occur that, as shown in
FIG. 19
, while the multiplexing unit reads the first TS packet P
1
corresponding to the first channel CH
1
which arrives at the input unit first (FIG.
19
A), the second TS packet P
2
corresponding to the second channel CH
2
to be read next does not arrive yet (FIG.
19
B), and the second TS packet P
2
arrives at “c” time after finishing to read of the first TS packet P
1
(FIG.
19
C).
Therefore, a gap g is generated between the first TS packet P
1
and the second TS packet P
2
out of the TS packets included in the transport stream TS
2
formed in the multiplexing unit (FIG.
19
). This case has been considered to cause a problem that, if the receiver decodes and reproduces the first TS packet P
1
and the second TS packet P
2
, a picture and voice are interrupted by the gap g generated between the first TS packet P
1
and the second TS packet P
2
.
Here, assuming that the number of channels to be input to the multiplexer is n and channels are represented as the channel
1
, channel
2
, channel
3
, . . . , channel n, a delay time due to the multiplexing for the channel
1
to the channel n will be explained. In this case, it is assumed that input rates for the channel
1
to channel n are R
1
, R
2
, R
3
, . . . , Rn [bits/sec] respectively, and that the number of bits buffered in memories (FIFO) for the channel
1
to the channel n are V
1
, V
2
, V
3
, . . . , Vn [bits] respectively. In addition, it is assumed that an output rate of outputting each multiplexed TS packet from the multiplexer is R [bits/sec]. Firstly, with respect to each TS packet to be input to the multiplexer, each encoder of a former stage performs such statistics multiplexing processing that the sum (R
1
+R
2
+R
3
+ . . . +Rn [bit/sec]) of input rates for the channel
1
to the channel n is equal to the output rate R [bits/sec]. In the statistics multiplexing processing, the input rates for the channel
1
to the channel n are varied. In this case, the sum (R
1
+R
2
+R
3
+ . . . +Rn [bit/sec]) of the input rates is obtained by the following equation (1) to be equal to the output rate R [bits/sec];
R=R
1
+
R
2
+
R
3
+ . . . +
Rn
[bits/sec] (1)
Since the transmission capacity for output is generally decided in advance, it can be assumed that the output rate R [bits/sec]) is fixed. Assuming that the total number of bits buffered in the memories for the channel
1
to the channel n is V [bits], the total V [bits] is obtained by the following equation (2);
V=V
1
+
V
2
+
V
3
+ . . . +
Vn
[bits] (2)
In this case, since the sum of the input rates (R
1
+R
2
+R
3
+ . . . +Rn [bits/sec]) is the output rate R [bits/sec], the total number V [bits] of bits is always fixed.
Here, the delay tim
Kubota Tatsuya
Matsumura Youichi
Frommer William S.
Frommer & Lawrence & Haug LLP
Onuaku Christopher
Sony Corporation
Tran Thai
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