Rate generator in a video on demand system having multiple constant bit rate data

• US 7,142,567 B1
• Filed: 12/10/1999
• Issued: 11/28/2006
• Est. Priority Date: 04/01/1999
• Status: Expired due to Term

• Current Assignee: Comcast IP Holdings I LLC (Comcast Corporation)
• Original Assignee: Sedna Patent Services LLC
• Inventors: Zack, Steven, Caracciolo, Gerald T.
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): NG, CHRISTINE Y
• Application Number:
  US09/459,237
• Time in Patent Office: 2,545 Days
• Field of Search: 370/516, 370/517, 370/518, 725/87, 725/101
• US Class Current: 370/516
• CPC Class Codes: H04N 21/23439 for generating different versions
• 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 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A rate generator for generating a plurality of different frequencies that represent video requests in a video on demand (VOD) system. The rate generator comprises a plurality of parallel groups, each group comprising a phase accumulator module having a plurality of phase accumulators, a phase increment model having a plurality of phase increment registers, and an adder, coupled to the phase accumulator module and the phase increment module. The adder sums the phase increment value from the phase from the phase increment module and the output of the phase accumulator module and provides the value back to the phase accumulator module. When the sum reaches a pre-determined value, the adder resets and generates a pulse at a frequency dependent on the phase increment and the sampling frequency. In addition, a method for deriving the rate generator architecture is also provided.

Claims

1. A rate generator for generating a plurality of frequencies comprising:

an oscillator comprising;

a phase accumulator for storing an accumulated phase value;

a phase increment register for storing a phase increment value; and

an adder, coupled to said phase accumulator and said phase increment register, for summing said phase increment value and the accumulated phase value to provide a sum to said phase accumulator, said adder for generating a pulse at a frequency each time the sum reaches a pre-determined value; and

a controller, coupled to said oscillator, for time sharing said phase accumulator, said phase increment register and said adder to operate said oscillator as a plurality of oscillators to produce a plurality of frequencies forming control signals for a memory storing a plurality of identifiers associated with a respective plurality of users.

2. The rate generator of claim 1 further comprising a plurality of oscillators and controllers.

3. The rate generator of claim 1 wherein said phase accumulator is an accumulated phase value storage for storing a plurality of accumulated phase values, said phase increment register is a phase increment value storage for storing a plurality of phase increment values, and said controller is a memory address generator for addressing said phase accumulator value storage and said phase increment value storage to timely apply said values to said adder.

4. The rate generator of claim 3 wherein the accumulated phase value storage stores 64 accumulated phase values and said phase increment value storage stores 64 phase increment values.

5. The rate controller of claim 1 wherein said plurality of oscillators is 64.

6. The rate controller of claim 1 wherein said plurality of frequencies form a write enable signal for a memory that stores stream identifiers.

7. A rate generator for generating a plurality of stream identifiers for a selected number of users, the rate generator comprising a plurality of parallel groups, each group comprising:

an address generator for generating a plurality of stream identifiers;

a phase increment source for generating a plurality of phase increments associated with the plurality of stream identifiers;

a phase accumulator module having a plurality of phase accumulators, said phase accumulator module for receiving an accumulated phase value and providing the phase value of one of the phase accumulators during a frequency cycle;

a phase increment module having a plurality of phase increment registers pre-loaded with a phase increment value, said phase increment module for providing an output of one of the phase increment registers during the frequency cycle;

an adder, coupled to said phase accumulator module and said phase increment module, for summing the phase increment value and the output of said phase accumulator module and providing the sum to said phase accumulator module, said adder for generating a pulse each time the sum reaches a pre-determined value; and

sequencing means, coupled to said address generator and said adder for pipelining the plurality of stream identifiers and for outputting one stream identifier each time said adder generates the pulse.

8. The rate generator of claim 7 wherein the plurality of stream identifiers comprise user identifier addresses in a video on demand system.

9. The rate generator of claim 7 wherein said sequencing means comprises a first-in-first-out (FIFO) queue.