Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1999-01-22
2002-07-02
Patel, Ajit (Department: 2662)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S503000, C370S537000
Reexamination Certificate
active
06414970
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a signal multiplexing method and apparatus for multiplexing digital picture or speech signals to generate degree-one multiplexed television-program-based streams, degree-two multiplexing these plural degree-one multiplexed streams to generate a degree-two multiplexed stream to transmit or record the generated degree-two multiplexed stream, a digital signal transmission method and apparatus, a digital signal recording method and apparatus, and to a recording medium having the multiplexed data recorded thereon.
2. Description of the Related Art
In ISO13818-1, there is prescribed a transport stream for multiplexing plural programs, such as television broadcast programs, into a sole multiplexed stream, and transmitting the multiplexed stream. Up to now, there is known a multiplexing system for generating this transport stream.
FIG. 1
shows a structure of a broadcast system transmitting this transport stream using, for example, a digital broadcasting satellite.
To a transmitting device
101
, base band video or audio data, associated with plural programs Pa to Pn, are sent from a server or a video camera. These video or audio data are sent to video encoders
102
a
to
102
n
and to audio encoders
103
a
to
103
n
, associated with the programs Pa to Pn, respectively, so as to be encoded to compressed data streams (elementary streams) conforming to, for example, MPEG (ISO/IEC11172, ISO133818).
The encoded elementary streams are sent to degree-one multiplexers
104
a
to
104
n
, associated with the programs Pa to Pn, respectively. The degree-one multiplexers
104
a
to
104
n
time-divisionally multiplex elementary streams, supplied on the program basis, in terms of the transport packets prescribed by ISO13818-1as unit, to generate degree-one multiplexed streams associated with the respective programs Pa to Pn.
The degree-one multiplexed streams, generated by the degree-one multiplexers
104
a
to
104
n
, are sent to a degree one multiplexer
105
which then time-divisionally multiplexes the degree-one multiplexed streams on the packet basis to generate a sole degree-two multiplexed stream.
This degree one multiplexer
105
sends the generated degree two multiplexed stream via the transmission medium to a reception device
111
.
The degree-one multiplexed streams, generated by the degree-one multiplexers
104
a
to
104
n
, are sent to a degree-two multiplexer
105
, which then time-divisionally multiplexes the respective degree-one multiplexed streams on the transport packet basis to generate a sole degree-two multiplexed stream.
The degree-two multiplexer
105
sends the generated degree-two multiplexed stream via a transmission medium
110
to a reception device
111
.
The degree-one multiplexed streams and the degree-two multiplexed stream, obtained on multiplexing by the degree-one multiplexers
104
a
to
104
n
and the degree-two multiplexer
105
, respectively, conform to the transport stream prescribed in ISO13818-1.
The transmission device
101
thus encodes the base-band video or audio data, associated with the programs Pa to Pn, to generate a sole degree-two multiplexed stream, which is sent to the reception device
111
via transmission medium
110
.
The degree-two multiplexed stream is transmitted via the transmission medium
110
to the reception device
111
. Specifically, the degree-two multiplexed stream is sent to a separator
112
. The separator
112
separates only the elementary stream associated with the program specified by the viewer from the degree-two multiplexed stream to send the separated elementary stream to a decoder. That is, the separator
112
sends the video elementary stream of the specified program to a video decoder
113
, while sending the audio elementary stream of the specified program to an audio decoder
114
.
The video decoder
113
and the audio decoder
114
expand or decode the compressed or encoded data to generate baseband video and audio data which are sent to an external equipment, not shown.
The reception device
111
thus receives the supplied degree-two multiplexed stream to select the predetermined program from the plural programs contained in the degree-two multiplexed stream by way of decoding.
FIG. 2
shows data structures of the degree-one multiplexed streams and the degree-two multiplexed stream, as the transport stream prescribed by the ISO13818-1.
The video elementary streams, encoded by the video encoders
102
a
to
102
n
, and audio elementary streams, encoded by the audio encoders
103
a
to
103
n
, are split into packets termed PES packets. The associated degree-one multiplexers
104
a
to
104
n
split the elementary streams into fixed-length transport packets, each being of
188
bytes, and time-divisionally degree-one multiplex the elementary streams on the transport packet basis to generate degree-one multiplexed streams. The degree-two multiplexer
105
time-divisionally degree-two multiplexes the respective degree-one multiplexed streams on the transport packet basis to generate the degree-two multiplexed stream.
FIG. 3
shows a decoder model of the reception device
111
in case the transport stream prescribed by the above-mentioned ISO13818-1 is supplied thereto.
A splitter
112
selects only the transport packets associated with the program and which have been selected by the viewer from the degree-two multiplexed stream to distribute the selected packets to transport buffers
116
to
118
. These transport buffers
116
to
118
transiently store the transport packets of the associated data. Specifically, the transport buffer
116
stores the transport packet of video data of the selected program, the transport buffer
117
stores the transport packet of audio data of the selected program and the transport buffer
118
stores the transport packet of program control data of the selected program. Although the transport buffer for title data etc is not shown, transport packets of title data, for example, if contained in the selected program, are stored in the associated transport buffers.
Each of the transport buffers
116
to
118
has a capacity of, for example,
512
bytes, and proceeds to leak the PES packets at a prescribed rate as long as data are stored therein.
The video data leaked from the transport buffer
116
is sent to a multiplexing buffer
119
. The audio data and the program control data, leaked from the transport buffers
117
,
118
, are sent to associated elementary buffers
121
,
122
, respectively.
From the multiplexing buffer
119
, only the elementary stream is leaked at a prescribed bitrate so as to be sent to the elementary buffer
120
.
At each decoding time point, decoders
123
to
125
extract elementary streams from the associated elementary buffers
120
,
121
,
122
, every decoding unit (termed an accessing unit) or every picture unit if the data is video data, in order to carry out decoding. The video data is decoded, using a re-order buffer
126
, for chronologically displaying pictures. The base-band video and audio data and control data, thus decoded, are sent to an external equipment or to a system controller.
By the above-described model, the reception device
111
decodes the transport stream prescribed by the above-mentioned ISO13818-1.
In the above-described broadcast system, employing digital satellite broadcast, it is possible to transmit transport streams, obtained on multiplexing data compressed every plural programs by the transmitting device
101
, and to demultiplex and decode the data by the reception device
111
.
Meanwhile, the total size of the multiplexing buffer
119
and the elementary buffer
120
(
121
,
122
) is the sum of the buffer size of the video buffering verifier (VBV) for controlling the amount of the generated codes and a size uniquely determined by the profile and the level prescribed in ISO13818-2. This sum is referred to hereinafter as a decoder buffer. Thus, each encoder of the transmitting device
101
controls the amount of the generated codes so as
Negishi Shinji
Tahara Katsumi
Yasuda Mikita
Frommer William S.
Frommer & Lawrence & Haug LLP
Patel Ajit
Sony Corporation
Tsegaye Saba
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