Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-02-26
2002-02-19
Britton, Howard (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C348S718000, C375S240250, C725S094000
Reexamination Certificate
active
06349115
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital signal encoding apparatus, a digital signal decoding apparatus, a digital signal transmitting apparatus and its method, and more specifically, is applicable to a digital satellite broadcasting.
2. Description of the Related Art
A digital satellite broadcasting system using stationary satellite has been started to be used. In
FIG. 1
, numeral
600
denotes a digital satellite broadcasting system as a whole. A transmission signal S
200
transmitted from a transmission antenna
200
is received and amplified by a satellite
300
to be output as a transmission signal S
300
. The transmission signal S
300
is received by a reception antennas
400
. Thereby, a broadcasting system having a wide service area which has little reception interference due to obstacles on the ground can be realized. The digital satellite broadcasting system uses an image compressive encoding method called moving picture experts groups (MPEG2) to multiplex a plurality of channels on one transport stream and transmit it.
In the digital satellite broadcasting system
600
shown in
FIG. 2
, video signals S
201
A to S
201
D and audio signals S
202
A to S
202
D are supplied from the exterior to an encoding transmitting apparatus
210
. In the encoding transmitting apparatus
210
, four encoding parts
220
A to
220
D which have the same construction are connected to a multiplexing part
250
, and the video signals S
201
A to S
201
D and the audio signals S
202
A to S
202
D are input to corresponding encoding parts
220
A to
220
D.
A video encoding part
221
and an audio encoding part
222
included in the encoding part
220
A respectively encode the video signal S
201
A and the audio signal S
202
A by using the MPEG2 method, and they are output to a transmission buffer
230
as video encoded data S
221
and audio encoded data S
222
respectively. The transmission buffer
230
temporarily stores the video encoded data S
221
and the audio encoded data S
222
, and then reads out them at a predetermined timing to output them to a multiplexing part
240
. The video encoding part
221
constantly checks the content by the amount of the video encoded data S
221
in the transmission buffer
230
as content information S
230
, and controls the amount of codes to be generated of the video encoded data S
221
based on the content information S
230
.
The multiplexing part
240
multiplexes the video encoded data S
221
and the audio encoded data S
222
and outputs the resultant to a multiplexing part
250
as multiplexed data S
220
A. The multiplexing part
250
multiplexes the multiplexed data S
220
A and the multiplexed data S
220
B to S
220
D respectively output from the encoding parts
220
B to
220
D, and outputs the resultant to a modulating part
260
as a transport stream S
250
. The modulating part
260
performs a predetermined modulation on the transport stream S
250
and transmits the resultant via the transmission antenna
200
as a transmission signal S
200
.
The satellite
300
receives and amplifies the transmission signal S
200
, and transmits the resultant as a transmission signal S
300
. In a decoding receiving apparatus
410
, the transmission signal S
300
is received by the reception antenna
400
to be demodulated at a demodulating part
420
, and is output to a separating part
430
as a transport stream S
240
. The separating part
430
selects one of the video encoded data and one of the audio encoded data among from the encoded data multiplexed on the transport stream S
420
in accordance with selection signal S
460
output from a remote controller
460
, and outputs these data to a reception buffer
440
as video encoded data S
431
and audio encoded data S
432
.
The video encoded data S
431
and the audio encoded data S
432
are temporarily stored in the reception buffer
440
and then they are read out at a predetermined timing to be decoded by a video decoding part
451
and an audio decoding part
452
. Thereafter, they are output to a television receiver (not shown) as a video signal S
451
and an audio signal S
452
.
Here, in the MPEG2 method, the amount of codes to be generated by an encoding processing changes depending on the pattern of each picture of image to be encoded. In short, when the pattern is complicated, the amount of codes to be generated increases, and when the pattern in simple, the amount of codes to be generated decreases. However, the transmission signals S
200
and S
300
are transmitted at a fixed rate, so that the transmission buffer
230
and the reception buffer
440
are provided to absorb the fluctuation of the rate.
In the digital satellite broadcasting system, so-called speckled broadcasting for broadcasting alternately a plurality of standard definition television (SDTV) channels and one high definition television (HDTV) channel in one transponder has been studied.
FIG. 3
shows an example of the speckled broadcasting. In one transponder, one channel of HDTV is broadcasted in one time slot, and four channels of SDTV are broadcasted in another time slot. In this way, the SDTV and the HDTV are broadcasted changeably, so that a broadcasting using the definition depending on the program contents can be performed.
The video encoding and video decoding of the HDTV are performed by a plurality of processors for SDTV which are combined.
FIG. 4
shows the decoding processing of HDTV image in a video decoding part
225
for HDTV. The HDTV screen area is divided into four areas to be parallel-processed by four decoding processors
225
A to
225
D so as to perform the decoding processing of HDTV which has larger data size than that of SDTV.
The video decoding part
225
consists of four decoding processors
225
A to
225
D for SDTV, so that it has an ability to decode four channels of SDTV at the same time. Thereby, as shown in
FIG. 4
, a parallel multichannel reception for decoding a plurality of SDTV at the same time by using the video decoding part
225
can be considered.
However, to perform the parallel multichannel reception in a receiving apparatus, the number of buffers equal to the number of channels of SDTV to be displayed is required. More specifically, as shown in
FIG. 5
, four reception buffers are required to perform the parallel multichannel reception for decoding four channels of SDTV at the same time. Thus, this case has a problem that the construction becomes complicated and the price raises.
SUMMARY OF THE INVENTION
In view of the foregoing, and object of this invention is to provide a digital signal encoding apparatus, digital signal decoding apparatus, digital signal transmitting apparatus and its method which can perform the parallel multichannel reception of SDTV with a simple construction.
The foregoing object and other objects of the invention have been achieved by the provision of a digital signal encoding apparatus, digital signal decoding apparatus, digital signal transmitting apparatus and its method, in which a transmission buffer and a reception buffer are each used as a single buffer when the first video signal is encoded and decoded. When the number N of second video signals which have the picture elements less than that of the first video signal are encoded and decoded, the transmission buffer and the reception buffer are divided into the number of the second video signals to use them as a plurality of divided transmission buffers and a plurality of divided reception buffers.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.
REFERENCES:
patent: 5068650 (1991-11-01), Fernandez et al.
patent: 5583562 (1996-12-01), Birch et al.
patent: 5604682 (1997-02-01), McLaughlin et al.
patent: 5610841 (1997-03-01), Tanaka et al.
patent: 5623311 (1997-04-01), Phillips et al.
patent: 5640210 (1997-06-01), Knee et al.
patent: 5646959 (1997-07-01), Kamis
Koyanagi Hideki
Tahara Katsumi
Britton Howard
Frommer William S.
Frommer & Lawrence & Haug LLP
Sony Corporation
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