Multiplex transmission method for motion picture signals and apparatus therefor

• US 5,534,926 A
• Filed: 03/16/1994
• Issued: 07/09/1996
• Est. Priority Date: 03/17/1993
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Koga, Toshio, Ohki, Junichi
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US08/213,588
• Time in Patent Office: 846 Days
• Field of Search: 348/385, 348/388, 348/469, 348/465, 348/487
• US Class Current: 375/240.25
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/2385 Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/242 Synchronization processes, e.g. processing of PCR [Program Clock References] arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer

Abstract

A multiplex transmission method and apparatus for motion picture signals. A transmission line constituted by transmission channels having different carrier frequencies is prepared. One of the transmission channels has a transmission rate almost equal to the long-term average of information generation speeds in encoding an arbitrary motion picture signal. The input motion picture signal is encoded by using inter-frame and intra-frame correlations, and encoded information is output for each image channel. The image channels are related in one-to-one correspondence with the transmission channels having the different carrier frequencies. When an image channel of interest, of the image channels, exhibits a large generated information amount representing the encoded information generation speed within a time interval determined by a predetermined transmission rate of the transmission line in advance, adaptive multiplexing is performed by dividing and distributing the encoded information of the image channel of interest to the transmission channels including the transmission channel of the image channel of interest. The encoded information divided/distributed by the adaptive multiplexing is transmitted for each allocated transmission channel.

Claims

1. A multiplex transmission method for motion picture signals, comprising the steps of:

preparing a transmission line constituted by a plurality of transmission channels having different carrier frequencies, one of the transmission channels having a transmission rate substantially equal to a long-term average of information generation speeds in encoding an arbitrary motion picture signal;

encoding the input motion picture signal by using inter-frame and intra-frame correlations;

relating the image channels in one-to-one correspondence with the transmission channels having the different carrier frequencies;

outputting encoded information for each image channel and a generated information amount representing a generation speed of the encoded information;

when an image channel of interest of the image channels exhibits a generated information amount, which represents the encoded information generation speed within a time interval, exceeding a predetermined transmission rate of said transmission line, performing adaptive multiplexing by designating output rates of the encoded information, supplying read clocks corresponding to the output rates, forming cells consisting of a plurality of bit strings of the encoded information, adding identification information indicating a relationship with the image channel to said cells, and, when at least one image channel of interest exhibits the generated information amount exceeding the predetermined transmission rate, dividing and distributing the cells of the image channel of interest to the transmission channels including the transmission channel of the image channel of interest; and

transmitting the cells divided/distributed by the adaptive multiplexing for each allocated transmission channel.

2. A method according to claim 1, wherein the transmission channels allocated by the adaptive multiplexing are selected such that carrier frequencies are adjacent to the image channel of interest.

3. A method according to claim 1, wherein when the image channel of interest has a lowest carrier frequency, the adaptive multiplexing is performed with respect to the transmission channel having an adjacent carrier frequency on a higher frequency side.

4. A method according to claim 1, wherein when the image channel of interest has a highest carrier frequency, the adaptive multiplexing is performed with respect to the transmission channel having an adjacent carrier frequency on a lower frequency side.

5. A method according to claim 1, wherein a maximum allowable number of image channels of interest is set in advance, and the encoded information is distributed to the image channels of interest within the set maximum allowable number.

6. A method according to claim 1, wherein at least one of the image channels is set in advance as the image channel of interest, and the encoded information is distributed to only the set image channel.

7. A method according to claim 1, wherein said transmission line is constituted by m (m:

an integer larger than

     3) transmission channels, and the encoded information is distributed to n (m≧

n≧

2) transmission channels by the adaptive multiplexing.

8. A method according to claim 1, wherein the generated information amount is an occupation amount of a memory in which the encoded information is temporarily stored upon encoding.

9. A method according to claim 1, wherein the transmission rate of the transmission channel is the number of cells of the encoded information which are transmitted per unit time.

10. A method according to claim 1, further comprising the steps of:

selecting transmission channels so that they are in one-to-one correspondence with a plurality of receiving means;

removing information other than the information of the image channel of interest;

arranging/supplying only the information corresponding to the image channel of interest;

decoding the information corresponding to the image channel of interest.

14. An apparatus according to claim 10, further comprising:

a plurality of receiving means for respectively receiving and decoding outputs from said transmitting means;

an image channel selection signal supplied to said plurality of receiving means for instructing each of said receiving means to select a respective transmission channel;

variable rate separating means for receiving outputs from said receiving means, removing information other than the information of the image channel of interest, arranging/supplying only the encoded information corresponding to the image channel of interest; and

a decoding means for decoding the output from the variable rate separating means into the motion picture signal by using a predetermined decoding scheme.

11. A multiplex transmission apparatus for motion picture signals, comprising:

a transmission line constituted by a plurality of transmission channels having different carrier frequencies, one of the transmission channels having a transmission rate substantially equal to a long-term average of information generation speeds in encoding an arbitrary motion picture signal;

a plurality of encoding means, arranged for the respective image channels, for encoding the input motion picture signal by using inter-frame and intra-frame correlations and outputting encoded information, each of said encoding means having a buffer memory for interfacing with said transmission line to temporarily store the encoded information and output at a designated rate, and outputting a generated information amount representing a generation speed of the encoded information;

variable rate multiplex means for designating an output rate of the encoded information with respect to each of said encoding means in accordance with the generated information amount output from said encoding means, supplying read clocks corresponding to the output rates to the encoding means, forming cells consisting of a plurality of bit strings of the encoded information, adding identification information indicating a relationship with the image channel to said cells output from each of said encoding means, and for, when at least one image channel of interest exhibits the generated information amount exceeding the predetermined transmission rate, dividing and distributing the cells of the image channel of interest to at least two transmission channels of the transmission channels, and outputting the cells for each transmission channel; and

a plurality of transmitting means for receiving the cells of the respective transmission channels from said variable rate multiplex means and outputting, at said designated output rate, signals caused to correspond to the respective transmission channels by using a predetermined modulation scheme.

12. An apparatus according to claim 11, further comprising:

a plurality of receiving means for respectively receiving and decoding outputs from said transmitting means;

variable rate separating means for receiving outputs from said receiving means, separating/grouping the outputs in units of the encoded information having the same identification information, and outputting the encoded information for the respective image channels at allocated rates; and

a plurality of decoding means for temporarily storing the encoded information output from said variable rate separating means for the respective image channels in rate matching buffer memories at respective allocated rates, and decoding outputs from the buffer memories into the motion picture signals by using a predetermined decoding scheme.

13. An apparatus according to claim 12, wherein when the generated information amount of the image channel of interest exceeds the predetermined transmission rate, said variable rate multiplexing means distributes the encoded information of the image channel of interest to a pre-designated specific transmission channel of the transmission channels, and outputs the information for each transmission channel, and said receiving means is arranged in correspondence with only the specific transmission channel to receive an output from said transmitting means in the specific transmission channel.

15. A multiplex transmission apparatus for motion picture signals, comprising:

a transmission line constituted by a plurality of transmission channels having different carrier frequencies, one of the transmission channels having a transmission rate substantially equal to a long-term average of information generation speeds in encoding an arbitrary motion picture signal;

a plurality of encoding means, arranged for the respective image channels, for encoding the input motion picture signal by using inter-frame and intra-frame correlations and outputting encoded information, each of said encoding means having a buffer memory for interfacing with said transmission line to temporarily store the encoded information and output at a designated rate, and outputting a generated information amount representing a generation speed of the encoded information;

variable rate multiplex means for designating an output rate of the encoded information with respect to each of said encoding means in accordance with the generated information amount output from said encoding means, adding identification information indicating a relationship with the image channel to an output from each of said encoding means, and for, when at least one image channel of interest exhibits the generated information amount exceeding the predetermined transmission rate, distributing the encoded information of the image channel of interest to at least two transmission channels of the transmission channels and outputting the information for each transmission channel;

a plurality of transmitting means for receiving pieces of information of the respective transmission channels from said variable rate multiplex means and outputting, at said designated output rate, signals caused to correspond to the respective transmission channels by using a predetermined modulation scheme;

a plurality of receiving means for respectively receiving and decoding outputs from said transmitting means;

variable rate separating means for receiving outputs from said receiving means, separating/grouping the outputs in units of the encoded information having the same identification information, and outputting the encoded information for the respective image channels at allocated rates; and

a plurality of decoding means for temporarily storing the encoded information output from said variable rate separating means for the respective image channels in rate matching buffer memories at respective allocated rates, and decoding outputs from the buffer memories into the motion picture signals by using a predetermined decoding scheme;

wherein when the generated information amount of the image channel of interest exceed the predetermined transmission rate, said variable rate multiplexing means distributes the encoded information of the image channel of interest to a pre-designated specific transmission channel of the transmission channels, and outputs the information for each transmission channel, and said receiving means is arranged in correspondence with only the specific transmission channel to receive an output from said transmitting means in the specific transmission channel.