Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1997-12-24
2001-06-26
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240260
Reexamination Certificate
active
06252907
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a demultiplexer and transport decoder employing the demultiplexer.
2. Discussion of Related Art
There have been proposed a lot of methods for transmission/reception format for digital processed picture and audio data between media. One of them is MPEG
2
system part proposed by MPEG
2
, which makes picture-compressed and audio-compressed data in a format which can be easily used, to transmit and receive the data between media. In the transmission and reception of video data and audio data, the video data and audio data are encoded, compressed, and multiplexed by MPEG transport encoder, to be transmitted. The multiplexed stream is received, and demultiplexed by MPEG transport decoder, and the video data and audio data are decoded by MPEG video decoder and audio decoder respectively, to be supplied to a user.
FIG. 1A
is a block diagram of a conventional MPEG decoder. The configuration and operation of the conventional MPEG decoder is explained with reference to FIG.
1
A. The MPEG encoder includes; first and second encoders
10
and
11
for encoding input video data and audio data, to output video bit stream and audio bit stream, respectively, first and second packetizers
12
and
13
for packetizing the video bit stream and audio bit stream sent from first and second encoders
10
and
11
; and a multiplexer
14
for multiplexing the packetized bit streams, to make one bit stream, and store or transmit it.
When video data is received, first encoder
10
compresses/codes the video data, to convert is into MPEG video bit stream. When audio data is received, second encoder
11
compresses/codes the audio data, to convert it into MPEG audio bit stream. The MPEG video bit stream converted by first encoder
10
is sent to first packetizer
12
, to be packetized in a proper length and output to multiplexer
14
. The audio bit stream compressed by second encoder
11
is sent to second packetizer
13
, to be packetized in a proper length and output to multiplexer
14
.
The video and audio streams are multiplexed by multiplexer,
14
, to be converted into one bit stream, and stored or transmitted through a channel. Multiplexer
14
, the transport multiplexer, not only receives MPEG video bit stream and audio bit stream but multiplexed compressed/coded video stored or transmitted through a channel. Multiplexer
14
, the transport multiplexer, not only receives MPEG video bit stream and audio bit stream but multiplexes compressed/coded video stream and audio stream other than the MPEG video and audio bit streams, to store them as one bit stream and transmit it through a channel. To decode a program consisting of video data and audio data and provide a user with it, a desired bit stream must be selected. For this, it is required that a specific identification (ID) is given to each bit stream, and information on the ID is additionally provided. Accordingly, the additional data is sent to the transport stream by multiplexer
14
, to be stored or transmitted. The configuration of the transport bit stream is shown in FIG.
1
B. In
FIG. 1B
, reference numeral H represents headers of the transport bit stream, P
1
A and P
2
A represent audio signal sections, P
1
V and P
2
V represent video signal sections, and hatched portion represents headers of packetized element stream (PEG).
FIG. 2A
illustrates a conventional typical MPEG transport decoder. The streams stored in multiplexer
14
shown in
FIG. 1A
or transmitted through a channel, that is, the streams transmitted through the airwaves, or stored is a CD-ROM and then reproduced, are applied to a first decoder
20
shown in FIG.
2
A. First decoder
20
tunes and demodulates a signal input and audio stream, and outputs them to second and third decoders
23
and
24
, respectively.
Second decoder
23
decodes the video stream, to reproduce a video signal according to an output timing signal supplied from a clock controller
22
. Third decoder
24
decodes the audio stream, to reproduce an audio signal according to the output timing control signal applied from clock controller
22
. The video and audio signals output from second and third decoders
23
and
24
are MPEG signals which do not include the above-described headers as shown in FIG.
2
C. These signals are not used for recording but used for displaying. In other words, demultiplexer
21
outputs the audio data and video data having no headers, decodes and displays them. Thus, when the data having no header is stored in a recording medium, it is impossible to reproduce the data from the medium.
That is, data is output from demultiplexer
21
in the form of packet, and multiple packets are divided into audio packet and video packet depending on their header information. Accordingly, because the conventional transport decoders output only audio data and video data which do not include header information, when the data is recorded in a recording medium, and then reproduced, it is impossible to confirm if the reproduced data is the audio packet or video packet. Thus, correct decoding cannot be performed. To enable the transport decoder to output both audio and video data for display as shown in FIG.
2
C and audio video data including headers for recording as shown in
FIG. 2B
, it requires two transport decoders
31
and
32
shown in FIG.
2
D.
First transport decoder
31
outputs the data for displaying, and second transport decoder
32
outputs the data including headers for recording. The data for displaying is displayed through a display
33
, and data for recording is recorded in a recording medium
34
. Here, clock controller
22
controls timing between second decoder
23
, third decoder
24
, demultiplexer
21
, to adjust lip sync or decoding rate between video data and audio data. Due to the broad and complicated transport stream of the conventional transport decoder, there are developing lots of program type transport demultiplexers. However, these demultiplexers can be variously applied according to programs, but their operation speed is deteriorated. Furthermore, the demultiplexers require additional cores other than necessary logics, increasing their sizes.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a demultiplexer and transport employing the same that substantially obviates one or more of the problems due to limitations and disadvantages or the related art.
An object of the present invention is to provide a transport demultiplexer which outputs recording data including headers, and simultaneously, outputs displaying data including no deader.
Another object of the present invention is to provide a hard-wired transport demultiplexer having smaller size and faster speed.
Still another object of the present invention is to provide a transport decoder which employing the aforementioned transport demultiplexer.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or maybe learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the demultiplexer, includes: a buffer for temporarily storing and outputting a transport stream, the transport stream consisting of header portion and payload portion, the header portion including a transport header and PES/PSI header; a controller for receiving the transport stream output from the buffer, and being operated according a mode signal applied thereto, to output the header portion and payload portion of the transport stream without any changes, a PES/PSI decoder for receiving the transport stream output from the buffer, and being operated according to the mode signal applied thereto, to decode only PES/PSI he
LG Electronics Inc.
Rao Andy
LandOfFree
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