Video system with selectable bit rate reduction

• US 6,097,435 A
• Filed: 01/31/1997
• Issued: 08/01/2000
• Est. Priority Date: 01/31/1997
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Inventors: Stanger, Leon, Plummer, Robert H., Yang, Chao-Kung
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US08/792,589
• Time in Patent Office: 1,278 Days
• Field of Search: 348/387, 348/390, 348/7, 370/468, 370/477
• US Class Current: 375/240.03
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 21/233 Processing of audio elementary streams monitoring, identification or recognition of audio in broadcast systems H04H60/58
• CPC Class Codes: H04N 21/2343 involving reformatting operations of video signals for distribution or compliance with end-user requests or end-user device requirements video transcoding H04N19/40; media packet handling at the source H04L65/762
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/23655 Statistical multiplexing, e.g. by controlling the encoder to alter its bitrate to optimize the bandwidth utilization
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams

Abstract

A video broadcast system is provided with an apparatus for processing a plurality of program signals corresponding to, for example, movies or other prerecorded programs, to selectively reduce the bandwidth required to transmit or broadcast the program signals. The signal processing apparatus includes a rate controller for generating a rate reduction factor based upon the data rates of the first and second program signals, a first channel processor coupled to receive the first program signal, and a second channel processor coupled to receive the second program signal. Each of the channel processors includes a data path for selectively reducing the bit rate of the program signals based upon the rate reduction factor.

Claims

1. An apparatus for processing a plurality of program signals including a first program signal having a first data rate and a second program signal having a second data rate, said apparatus comprising:

a rate controller for generating a rate reduction factor based upon said data rates of said first and second program signals;

a first channel processor coupled to receive said first program signal, said first program signal including a first audio signal and a first video signal, said first channel processor comprising;

a first data path providing a first bit reduction rate;

a second data path providing a second bit reduction rate which is greater than said first bit reduction rate; and

a channel controller for selectively causing said first video signal to pass through one of said first and second data paths without passing through the other of said first and second data paths in response to said rate reduction factor generated by said rate controller;

a second channel processor coupled to receive said second program signal, said second program signal including a second audio signal and a second video signal, said second channel processor comprising;

a first data path providing a first bit reduction rate;

a second data path providing a second bit reduction rate which is greater than said first bit reduction rate of said first data path of said second channel processor; and

a channel controller for selectively causing said second video signal to pass through one of said first and second data paths of said second channel processor without passing through the other of said first and second data paths of said second channel processor in response to said rate reduction factor generated by said rate controller.

2. An apparatus as defined in claim 1 wherein said rate controller comprises:

means for determining the combined data rate of said first and second program signals; and

means for determining said rate reduction factor based on said combined data rate.

3. An apparatus as defined in claim 1 wherein one of said channel processors additionally comprises:

an input buffer;

an inverse quantizer;

a quantizer;

an output buffer;

switch means for causing one of said program signals to pass through said input buffer and said output buffer without passing through said quantizer or said inverse quantizer; and

switch means for causing one of said program signals to pass through said input buffer, said output buffer, said quantizer, and said inverse quantizer.

4. An apparatus as defined in claim 3 wherein said first channel processor additionally comprises:

a demultiplexer for demultiplexing said first program signal into said first video signal and said first audio signal;

a delay buffer coupled to receive said first audio signal, said delay buffer providing an adjustable time delay of said first audio signal; and

a multiplexer for multiplexing said first audio signal together with said first video signal.

5. An apparatus as defined in claim 1 wherein said first data path of said first channel processor comprises means for passing said first video signal through said first channel processor without decompressing or recompressing said first video signal and wherein said second data path of said first channel processor comprises:

means for decompressing said first video signal;

means for recompressing said first video signal; and

means for providing said first video signal from said decompressing means to said recompressing means.

6. An apparatus as defined in claim 1 wherein said first data path provides no bit reduction and wherein said channel controller of said first channel processor comprises:

means for comparing said rate reduction factor with a predetermined threshold; and

means for causing said first video signal to pass through said first data path of said first channel processor if said reduction factor is not less than said predetermined threshold and for causing said first video signal to pass through said second data path of said first channel processor if said reduction factor is less than said predetermined threshold.

7. An apparatus as defined in claim 1,

wherein said first channel processor additionally comprises a third data path providing a third bit reduction rate which is greater than said second bit reduction rate,

wherein said channel controller of said first channel processor selectively causes said first video signal to pass through only one of said first, second and third data paths in response to said rate reduction factor generated by said rate controller,

wherein said second channel processor additionally comprises a third data path providing a third bit reduction rate which is greater than said second bit reduction rate of said second data path of said second channel processor, and

wherein said channel controller of said second channel processor selectively causes said second video signal to pass through only one of said first, second and third data paths of said second channel processor in response to said rate reduction factor generated by said rate controller.

8. An apparatus for processing a plurality of program signals including a first program signal having a first data rate and a second program signal having a second data rate, said apparatus comprising:

a rate controller for generating a rate reduction factor based upon said data rates of said first and second program signals;

a first channel processor coupled to receive said first program signal, said first program signal including a first audio signal and a first video signal, said first channel processor comprising;

a first data path providing a first bit reduction rate;

a second data path providing a second bit reduction rate which is greater than said first bit reduction rate;

a channel controller for selectively causing the bit rate of said first video signal to be reduced by said first bit rate reduction or said second bit rate reduction in response to said rate reduction factor generated by said rate controller;

a second channel processor coupled to receive said second program signal, said second program signal including a second audio signal and a second video signal, said second channel processor comprising;

a first data path providing a first bit reduction rate;

a second data path providing a second bit reduction rate which is greater than said first bit reduction rate of said first data path of said second channel processor; and

a channel controller for selectively causing the bit rate of said second video signal to be reduced by said first bit reduction rate or said second bit reduction rate in response to said rate reduction factor generated by said rate controller.

9. An apparatus as defined in claim 8 wherein said rate controller comprises:

means for determining the combined data rate of said first and second program signals; and

means for determining said rate reduction factor based on said combined data rate.

10. An apparatus as defined in claim 8 wherein said first channel processor additionally comprises:

a demultiplexer for demultiplexing said first program signal into said first video signal and said first audio signal;

a delay buffer coupled to receive said first audio signal, said delay buffer providing an adjustable time delay of said first audio signal; and

a multiplexer for multiplexing said first audio signal together with said first video signal.

11. An apparatus as defined in claim 8,

wherein said first data path of said first channel processor comprises means for passing said first video signal through said first channel processor without decompressing or recompressing said first video signal, and

wherein said second data path of said first channel processor comprises:

first means for decompressing said first video signal;

first means for recompressing said first video signal; and

means for providing said first video signal from said first decompressing means to said first recompressing means.

12. An apparatus for processing a plurality of program signals including a first program signal having a first data rate and a second program signal having a second data rate, said apparatus comprising:

a rate controller for generating a rate reduction factor based upon said data rates of said first and second program signals;

a first channel processor coupled to receive said first program signal, said first program signal including a first video signal, said first channel processor comprising;

a signal decompression circuit through which said first video signal passes;

a signal compression circuit through which said first video signal passes, said signal compression circuit providing a variable amount of bit rate reduction; and

a channel controller for controlling the amount of bit rate reduction provided to said first video signal by said signal compression circuit processor based upon said rate reduction factor generated by said rate controller;

a second channel processor coupled to receive said second program signal, said second program signal including a second video signal, said second channel processor comprising;

a signal decompression circuit through which said second video signal passes;

a signal compression circuit through which said second video signal passes, said signal compression circuit of said second channel processor providing a variable amount of bit rate reduction; and

a channel controller for controlling the amount of bit rate reduction provided to said second video signal by said signal compression circuit of said second channel processor based upon said rate reduction factor generated by said rate controller.

13. An apparatus as defined in claim 12 wherein one of said signal decompression circuits comprises an inverse quantizer and wherein one of said signal compression circuits comprises a quantizer.

14. An apparatus as defined in claim 13 wherein one of said channel processors additionally comprises:

an inverse VLE circuit through which one of said video signals passes;

a VLE circuit through which one of said video signals passes.

15. An apparatus as defined in claim 12 additionally comprising:

a multiplexer coupled to receive said first and second program signals from said first and second channel processors; and

means coupled to said multiplexer for receiving said first and second program signals from said multiplexer and broadcasting said program signals to a plurality of locations remote from said multiplexer.

16. A system as defined in claim 15 wherein said broadcasting means comprises:

a transmitter coupled to receive said first and second program signals from said multiplexer;

a satellite coupled to receive said first and second program signals from said transmitter;

a receiver for receiving program signals from said satellite; and

a decoder connected to receive program signals from said receiver.

17. A method of processing a program signal which includes a video signal, said method comprising the steps of:

(a) comparing a factor relating to the complexity of said video signal to a threshold;

(b) reducing the bit rate of said video signal by a first amount depending on whether said factor is greater than or less than said threshold; and

(c) reducing the bit rate of said video signal by a second amount depending on whether said factor is greater than or less than said threshold.

18. A method as defined in claim 17 additionally comprising the steps of:

(d) comparing said complexity factor to a second threshold;

(e) reducing the bit rate of said video signal by a third amount depending on whether said factor is greater than or less than said second threshold.

19. A method as defined in claim 17 additionally comprising the steps of:

(d) multiplexing said video signal with a plurality of other video signals at a broadcast location to form a multiplexed signal; and

(e) broadcasting said multiplexed signal to a plurality of locations remote from said broadcast location.

20. A method as defined in claim 17 wherein said step (c) comprises the step of routing said video signal through a data path having a quantization circuit and an inverse quantization circuit.