Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1998-01-28
2001-07-31
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C348S423100
Reexamination Certificate
active
06269107
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to an MPEG-2 (Moving Picture Experts Group; An international standard 2 for moving picture compression in a media integrated system, hereinafter called ‘MPEG-2’) which multiplexes multimedia, and more particularly, to device and method for demultiplexing a transport stream (TS), which is suitable for fast processing and transmission of transport stream packets of TV signal by a fixed length transport packet unit.
2. Discussion of the Related Art
In general, the multiplexing by packets is, for example, in case of multiplexing of video and audio, is a system in which video and audio are respectively divided into appropriate lengths of bit streams called as ‘packets’, additional information, such as header, is attached thereto, and time-division transmitted. This time-division transmission system is applied to data compression of communication and digital DBS (Direct Broadcasting System) receiver. In a broadcasting station, a TV signal is converted into a digital TV signal, compressed, and transmitted to a satellite, the satellite receives the TV signal, amplifies, and transmits the signal trough a relay again, and the TV signal relayed through the communication satellite is received at a receiver or decoder and demodulated, thereby a program broadcasted from a broadcasting station can be watched. In this case, in the broadcasting station, video, audio and data signal are converted into digital signals, compressed, and formed into a packet stream, to provide one TV signal stream. Plural digital TV signal streams are multiplexed in a transport multiplexer into transport stream packets and provided to a channel encoder. The transport stream packets has a size of 188 byte unit and a data rate RU of approx. 40~45 Mbps.
FIG. 1
illustrates a block diagram of a background art device for demultiplexing a transport stream, showing CL9110 transport layer demultiplexer of C-Cube Co. Ltd. as an example.
Referring to
FIG. 1
, the background art device for demultiplexing a transport stream
10
, integrated into one chip, is provided with a packet framer
11
for receiving an MPEG-2 data and re-framing into transport stream packet units, a first FIFO buffer
12
for temporary storage of the transport stream packets from the packet framer
11
in byte units, a RISC (Reduced Instruction Set Computer) engine
13
for making the packets stored in the first FIFO buffer
12
responsive to demands from devices there around, such as a program/data RAM
23
or a descrambler interface
14
, a second FIFO buffer
15
for temporary storage of the packets interfaced in the RISC engine
13
, and a memory controller
16
for making the packets stored in the second FIFO buffer
15
to exchange information with local DRAM (not shown) and controlling transmission of parsed bit streams to a video interface
24
, audio interface
25
and high speed interface
17
. There are a PCR recovery
18
for providing PCR (Program Clock Reference) information so that the packet framer
11
sets an STC (System Time Clock; reference synchronization information) as desired, a voltage control oscillator
19
for providing the STC to the PCR recovery
18
, and a RC filter
20
for linear filtering the STC from the PCR recovery
18
into an oscillating signal and providing the PCR recovery
18
and the packet framer
11
through a bus line. The packet framer
11
is connected to interfaces, such as an I
2
C interface
21
, an host interface
22
, a program/data RAM
23
, a video interface
24
, an audio interface
25
, and a high speed interface
17
through a common bus line.
When an MPEG-2 transport data is reached to the packet framer
11
, the aforementioned background art device for demultiplexing a transport stream
10
has a PCR information set through the voltage control oscillator
19
and the RC filter
20
matched to timing of bytes of a bit stream carrying a PCR. And, the packet framer
11
picks up information suitable for composing a transport stream packet through bus line communication with the I
2
C interface
21
, the host interface
22
, the program/data RAM
23
, the video interface
24
, the audio interface
25
and the memory controller
16
, which are connected with peripheral devices. The packet framer
11
then reframes MPEG-2 transport data received in bit units successively into transport stream packets to meet the requirements of the information. The reframed transport stream packet is temporarily stored in the first FIFO buffer
12
, determined of its scrambling by partial decoding of the transport stream packet in the RISC engine
13
, and decoded in response to a control signal from the program/data RAM
23
. Then, the decoded data (video or audio information) is temporarily stored in the second FIFO buffer
15
through the RISC engine
13
and stored in the external local DRAM through the memory controller
16
. The data, temporarily stored in the second FIFO buffer
15
, is provided to the video interface
24
and the audio interface
25
through the bus line under the control of the memory controller
16
and presented as a video stream and a audio stream. When there are external demands for data on the transport stream packet, the transport packets composed in the packet framer
11
is provided to an external device through the high speed interface
17
.
The aforementioned background art device for demultiplexing a transport stream has an advantage of enabling a program conversion due to the use of the program/data RAM, but has disadvantage in the large sized hardware with a difficulty of cost down due to provision of the FIFO buffers at input/output terminals of the RISC engine to cope with the irregular data processing rate of the RISC engine.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to device and method for demultiplexing a transport stream that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide device and method for demultiplexing a transport stream which allows a real-time decoding of the transport stream.
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 may be 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 device for demultiplexing a transport stream includes a synchronization and fetch controller for checking a synchronization byte of a received transport stream, a first subdecoder for comparing a packet identification number of the transport stream to an individual bit stream of the packet under the control of the synchronization and fetch controller, for filtering designated packets only, a second subdecoder for extracting a program clock reference information of the transport stream under the control of the first subdecoder, a descrambler for recovering a scramble signal from payload information in the transport stream under the control of the first subdecoder or the second subdecoder, a multiplexer for multiplexing the transport stream or descrambled signal under the control of the first subdecoder and the second subdecoder, and a third subdecoder for extracting a presentation time information of the transport stream or a stream from the multiplexer and providing a control signal to the multiplexer and the descrambler.
In another aspect of the present invention, there is provided a method for demultiplexing a transport stream including the steps of (1) comparing a packet identification number of a transport stream to an individual bit stream of the packet after checking a synchronization byte of the received transport stream, for
Fleshner & Kim LLP
LG Electronics Inc.
Marcelo Melvin
LandOfFree
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