Variable length code multiplexer and variable length code demultiplexer

• US 20030043859A1
• Filed: 08/19/2002
• Published: 03/06/2003
• Est. Priority Date: 09/04/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tasaki, Hirohisa
• Granted Patent: US 7,420,993 B2
• Time in Patent Office: Days
• US Class Current: 370/537
• CPC Class Codes: H04J 3/1688 the demands of the users being taken into account after redundancy removal, e.g. by predictive coding, by variable sampling reducing bandwidth of signals in general H04B1/66; in PCM-systems H04B14/046; removal of redundancy in telegraph communication H03M7/30
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/69 involving reversible variable length codes [RVLC]
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 7/52 Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434

Abstract

A variable length code multiplexer multiplexes a plurality of input codes (102) including a variable length code into a multiplexed code (121) and outputs the multiplexed code (121). The multiplexer includes a forward direction multiplexing unit (22) for multiplexing the plurality of input codes (102) one by one so that they are running in a forward direction from a head of the multiplexed code (121) to a tail of the multiplexed code (121), a backward direction multiplexing unit (23) for multiplexing the plurality of input codes (102) one by one so that they are running in a backward direction from the tail of the multiplexed code (121) to the head of the multiplexed code (121), and a selection unit (25) for selecting either the forward direction multiplexing unit (22) or the backward direction multiplexing unit (23) for each of the plurality of input codes (102).

Claims

1. A variable length code multiplexer that multiplexes a plurality of input codes including a variable length code into a multiplexed code and outputs the multiplexed code, said multiplexer comprising:

a forward direction multiplexing means for multiplexing the plurality of input codes one by one so that they are running in a forward direction from a head of the multiplexed code to a tail of the multiplexed code;

a backward direction multiplexing means for multiplexing the plurality of input codes one by one so that they are running in a backward direction from the tail of the multiplexed code to the head of the multiplexed code; and

a selection means for selecting either said forward direction multiplexing means or said backward direction multiplexing means for each of the plurality of input codes.

2. The variable length code multiplexer according to claim 1, wherein the tail of the multiplexed code is fixed.

3. The variable length code multiplexer according to claim 1, further comprising a code length calculation means for determining a total code length of the plurality of input codes, wherein said backward direction multiplexing means determines the tail of the multiplexed code based on the total code length determined by said code length calculation means.

4. The variable length code multiplexer according to claim 1, wherein said selection means alternately selects either said forward direction multiplexing means or said back ward direction multiplexing means for each of the plurality of input codes.

5. The variable length code multiplexer according to claim 1, wherein said forward direction multiplexing means outputs a length of input codes which have already been multiplexed into the multiplexed code as an already-multiplexed code length, and said selection means selects either said forward direction multiplexing means or said backward direction multiplexing means based on the already-multiplexed code length from said forward direction multiplexing means.

6. The variable length code multiplexer according to claim 5, wherein when the already-multiplexed code length from said forward direction multiplexing means is less than a predetermined value, said selection means selects said forward direction multiplexing means.

7. A variable length code demultiplexer that demultiplexes a multiplexed code into a plurality of output codes including a variable length code and outputs the plurality of output codes, said demultiplexer comprising:

a forward direction demultiplexing means for demultiplexing the multiplexed code into the plurality of output codes one by one so that they are separated from respective areas of the multiplexed code running in a forward direction from a head of the multiplexed code to a tail of the multiplexed code;

a backward direction demultiplexing means for demultiplexing the multiplexed code into the plurality of output codes one by one so that they are separated from respective areas of the multiplexed code running in a backward direction from the tail of the multiplexed code to the head of the multiplexed code; and

a selection means for selecting either said forward direction demultiplexing means or said backward direction demultiplexing means for each of the plurality of output codes.

8. The variable length code demultiplexer according to claim 7, wherein the tail of the multiplexed code is fixed.

9. The variable length code demultiplexer according to claim 7, further comprising a code length decoding means for determining a total code length of the multiplexed code, wherein said backward direction demultiplexing means determines the tail of the multiplexed code based on the total code length determined by said code length decoding means.

10. The variable length code demultiplexer according to claim 7, further comprising a means for determining a total code length of the multiplexed code based on an identification signal identifying boundaries of the multiplexed code for each frame, wherein said backward direction demultiplexing means determines the tail of the multiplexed code based on the total code length of the multiplexed code.

11. The variable length code demultiplexer according to claim 7, wherein said selection means alternately selects either said forward direction demultiplexing means or said backward direction demultiplexing means for each of the plurality of output codes.

12. The variable length code demultiplexer according to claim 7, wherein said forward direction demultiplexing means outputs a length of codes which have already been separated from the multiplexed code as an already-demultiplexed code length, and said selection means selects either said forward direction demultiplexing means or said backward direction demultiplexing means based on the already-demultiplexed code length from said forward direction demultiplexing means.

13. The variable length code demultiplexer according to claim 12, wherein when the already-demultiplexed code length from said forward direction demultiplexing means is less than a predetermined value, said selection means selects said forward direction demultiplexing means.