System and method for transporting a compressed video and data bit stream over a communication channel

• US 20020159457A1
• Filed: 12/19/2000
• Published: 10/31/2002
• Est. Priority Date: 06/26/1997
• Status: Active Grant

• Current Assignee: Fang Wu, Ji Zhang, Wen H. Chen
• Original Assignee: Fang Wu, Ji Zhang, Wen H. Chen
• Inventors: Wu, Fang, Zhang, Ji, Chen, Wen H.
• Granted Patent: US 6,891,854 B2
• Time in Patent Office: Days
• US Class Current: 370/391
• CPC Class Codes: H04L 2012/5636 Monitoring or policing, e.g. compliance with allocated rate, corrective actions
• CPC Class Codes: H04L 2012/5664 Support of Video, e.g. MPEG
• CPC Class Codes: H04L 2012/5671 Support of voice
• CPC Class Codes: H04L 2012/5672 Multiplexing, e.g. coding, scrambling
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data
• 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 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• 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 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/6373 for rate control , e.g. request to the server to modify its transmission rate flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/6377 directed to server one-way streaming services wherein the source is controlled by the destination H04L65/613
• CPC Class Codes: H04N 21/6379 directed to encoder , e.g. for requesting a lower encoding rate
• CPC Class Codes: H04N 21/658 Transmission by the client directed to the server
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

Digitally compressed video/audio bit streams, when transmitted over digital communication channels such as digital subscriber loop (DSL) access networks, ATM networks, satellite, or wireless digital transmission facilities, can be corrupted due to lack of sufficient channel bandwidth. This invention describes schemes to ensure lossless transmission of bit streams containing pre-compressed video signals within the communication channels. The schemes herein comprises a rate conversion system that converts the bit rate of a pre-compressed video bit stream from one bit rate to another, and that is integrated with a digital communication channel, and a means to convey the maximum channel transmission rate to the rate conversion system to allow satisfactory transmission of the bit stream from the input of the rate converter through the transmission facility.

Claims

1. An apparatus for providing compressed video data onto a network, the apparatus comprising:

a bit rate converter having an input, a control input and an output, the input coupled to receive a first bitstream having a first bit rate, the bit rate converter configured to convert the first bitstream to a second bitstream having a second bit rate, different from the first bit rate, the second bitstream being provided at the output of the bit rate converter;

a rate controller coupled to the control input of the bit rate controller and configured to provide the second bit rate; and

a transmitter coupled to receive the second bitstream having the second bit rate and transmit the second bitstream onto the network.

2. The apparatus of claim 1 wherein the rate controller is coupled to a line that receives a control signal indicating one of the second bit rate and an amount of bit rate conversion for the first bitstream.

3. The apparatus of claim 2 wherein the rate controller is external to the apparatus and the line receives the second bit rate from an ATM network.

4. The apparatus of claim 2 wherein the transmitter is a RADSL transmitter and wherein the line is coupled to the RADSL transmitter and receives the second bit rate from the RADSL transmitter.

5. The apparatus of claim 1 wherein the bit rate converter comprises a set of modification units.

6. The apparatus of claim 5 wherein the modification units includes at least one of:

a modification unit capable of reducing the number of bits needed for discrete cosine transform coefficients, a modification unit capable of reducing the number of bits needed for motion vectors, and a modification unit capable of reducing the number of bits needed for auxiliary information.

7. The apparatus of claim 5 wherein the rate controller provides a bit rate control signal to each of the modification units.

8. The apparatus of claim 7 wherein the bit rate control signal specifies the amount of modifying each of the modifications units performs to achieve the second bit rate for the second bitstream.

9. The apparatus of claim 1 further including a multiplexer and wherein the rate controller controls the bit rate at which the multiplexer outputs data.

10. The apparatus of claim 1 wherein the rate controller controls the bit usage of each video frame in the second bitstream.

11. The apparatus of claim 1, wherein the transmitter is an xDSL transmitter and wherein the channel is a twisted copper wire.

12. The apparatus of claim 1, wherein the transmitter includes an ATM cell converter, the network includes an ATM network, and the second bit rate is about equal to an available connection capacity within the ATM network.

13. The apparatus of claim 1 further comprising a receiver coupled to a physical medium included in a channel.

14. The apparatus of claim 13 wherein the receiver is an RADSL receiver having an input and an output, the input of the RADSL receiver coupled to the physical medium.

15. The apparatus of claim 1 wherein the second bitstream comprises MPEG compressed video data.

16. The apparatus of claim 1 wherein the second bit rate is less than the first bit rate.

19. The apparatus of claim 18 wherein the means for outputting the second bitstream is an xDSL transmitter means for allowing reliable transmission of the second bitstream and wherein the channel is a twisted copper wire.

20. The apparatus of claim 19 wherein the xDSL transmitter means is a RADSL transmitter means that includes a multiplexer and synchronization control, an interleaver, a constellation encoder, and a DAC and analog signal processor coupled in series.

21. The apparatus of claim 18 wherein the means for transmitting the second bitstream transmits a compressed bitstream compressed according to one of an MPEG-x standard and a H.xxx standard.

17. A computer readable medium including instructions for a method of providing compressed video data onto a network, the instructions comprising

instructions for determining the bandwidth of the channel;

instructions for receiving a bitstream;

instructions for converting the bitstream to have a bit rate less than or equal to the bandwidth of the channel, wherein converting the bitstream includes changing data in the bitstream; and

instructions for transmitting the converted bitstream over the channel.

18. An apparatus for modifying a bit rate of a bitstream to use an available bandwidth of a channel, the apparatus comprising:

(a) means for converting a first bitstream at a first bit rate to a second bitstream at a second bit rate, different from the first bit rate, said means for converting comprising;

(i) means for receiving the first bitstream at the first bit rate,

(ii) means for receiving a control signal indicating a value for the second bit rate, and

(iii) means for outputting the second bitstream; and

(b) means for transmitting the second bitstream over a channel, the means for transmitting comprising;

(i) means to receive the second bitstream, the means to receive the second bitstream coupled to the means for outputting the second bitstream,

(ii) means coupled to the control input means of the bit rate converter to send a control signal indicating a value for the second bit rate, and

(iii) means for outputting the second bitstream from the means for transmitting to the channel.

22. An apparatus for providing compressed video data onto a network, the apparatus comprising:

(a) means for converting a first bitstream including the video data at a first bit rate to a second bitstream including the video data at a second bit rate, different from the first bit rate, said means for converting comprising;

(i) means for receiving the first bitstream at the first bit rate,

(ii) means for receiving a control signal indicating a value for the second bit rate, and

(iii) means for outputting the second bitstream;

(b) means for providing the control signal indicating the value for the second bit rate to the control input means of the bit rate controller; and

(c) means for transmitting the second bitstream over a channel, the means for transmitting comprising;

(i) means coupled to the means to receive the second bitstream having the second bit rate, and

(ii) means for outputting the second bitstream including the video data onto the network.

23. The apparatus of claim 22 wherein the means for providing the control signal is external to the apparatus and receives the second bit rate from an ATM network.

24. The apparatus of claim 22 further including a multiplexer means for multiplexing multiple bitstreams and outputting the second bitstream and wherein the means for providing the control signal controls the bit rate at which the multiplexer means outputs data.