Technique for communicating variable bit rate data over a constant bit rate link

• US 20030235219A1
• Filed: 06/19/2002
• Published: 12/25/2003
• Est. Priority Date: 06/19/2002
• Status: Active Grant

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Atlinks USA Incorporated (Verdoso Investmentssa)
• Inventors: Majumdar, Jayanta, Zhang, James Zhiming, Kapadia, Maneck Behram
• Granted Patent: US 6,956,875 B2
• Time in Patent Office: Days
• US Class Current: 370/535
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56

Abstract

Variable bit rate information is transmitted across a transmission link (20) at a constant bit rate by multiplexing individual variable bit rate elementary data streams (16₁ and 16₂) into a composite data stream (18) having a constant bit rate. A receiving device (22) receives the constant bit rate stream but delays processing thereof by an interval typically a fraction of the transmission interval. Following the delay interval, the receiving device processes the data at a rate that is independent of, but typically not greater than, the constant bit rate.

Claims

1. A method for communicating variable bit rate information, comprising the steps of:

receiving at a receiving device a composite data stream transmitted across a link at a constant bit rate not less than a highest peak rate of a set of variable bit rate elementary data streams that comprise composite data rate;

delaying processing at the receiving device of the composite data stream by a delay interval less than a total transmission time for the composite data stream; and

processing the composite data stream at the receiving device after said delay interval, the processing occurring at a rate independent of the constant bit rate.

2. The method according to claim 1 wherein the processing rate of the receiving device does not exceed the constant bit rate.

3. The method according to claim 1 wherein the delay interval is increased if there exists a period during which the constant bit rate does not exceed a peak receiving device processing rate.

4. The method according to claim 1 wherein the receiving step includes the sub-steps of:

storing successive bytes of the composite data stream in a buffer;

checking whether a prescribed number of bytes have been stored; and

ceasing the storage of bytes once a prescribed number of bytes have been received.

5. The method according to claim 1 wherein the processing step includes the sub-steps of:

recovering from the composite data stream clock references;

de-multiplexing the composite data stream into constituent elementary data streams;

determining if any elementary data stream has a packet with a time stamp matching a current system time, and if so,

determining whether the packet has a packet decode stamp matching the current system time, and if so, then decoding/uncompressing the packet;

determining if the packet has a presentation time stamp matching the current time, and if so,

rendering the packet.

6. The method according to claim 5 wherein the step of rendering the packet includes displaying the packet.

7. The method according to claim 5 wherein the step of rendering the packet includes further processing the packet via a CODEC.

8. A method for communicating variable bit rate information, comprising the steps of:

transmitting a composite data stream across a link at a constant bit rate not less than a highest peak rate of a set of variable bit rate elementary data streams that comprise composite data rate;

receiving the composite data stream at a receiving device;

delay interval less than a total transmission time for the composite data stream; and

processing the composite data stream at the receiving device after said delay interval, the processing occurring at a rate independent of the constant bit rate at which the composite data stream is transmitted.

9. The method according to claim 8 wherein the step of transmitting the composite data stream includes the step of multiplexing a plurality of elementary data streams to yield the composite data stream.

10. The method according to claim 8 wherein the processing rate of the receiving device does not exceed the constant bit rate at which the composite data stream is transmitted.

11. The method according to claim 8 wherein the delay interval is increased if there exists a period during which the constant bit rate does not exceed a peak receiving device processing rate.

12. The method according to claim 8 wherein the receiving step includes the sub-steps of:

storing successive bytes of the composite data stream in a buffer;

checking whether a prescribed number of bytes have been stored; and

ceasing the storage of bytes once a prescribed number of bytes have been received.

13. The method according to claim 8 wherein the processing step includes the sub-steps of:

recovering from the composite data stream clock references;

de-multiplexing the composite data stream into constituent elementary data streams;

determining if any elementary data stream has a packet with a time stamp matching a current system time, and if so,

determining whether the packet has a packet decode stamp matching the current system time, and if so, then decoding/uncompressing the packet;

determining if the packet has a presentation time stamp matching the current time, and if so,

rendering the packet.

14. The method according to claim 13 wherein the step of rendering the packet includes displaying the packet.

15. The method according to claim 13 wherein the step of rendering the packet includes further processing the packet via a CODEC.

16. Apparatus for receiving variable bit rate information, comprising:

a receiving device that receives composite data stream transmitted across a link at a constant bit rate not less than a highest peak rate of a set of elementary data streams that comprise composite data rate;

the receiving device having a buffer for storing at least a portion of the composite data stream; and

the receiving device delaying processing the composite data stream by a delay interval less than a total transmission time for the composite data stream; and

following the delay interval, the receiving device processing the composite data stream at a rate independent of the constant bit rate.

17. A communications system, comprising:

a transmitter for transmitting a composite data stream across a link at a constant bit rate not less than a highest peak rate of a set of variable bit rate elementary data streams that comprise composite data rate;

a receiving device that receives composite data stream transmitted across a link at a constant bit rate not less than a highest peak rate of a set of elementary data streams that comprise composite data rate;

the receiving device having a buffer for storing at least a portion of the composite data stream; and

the receiving device delaying processing the composite data stream by a delay interval less than a total transmission time for the composite data stream; and

stream at a rate independent of the constant bit rate.