Method and apparatus for determining a transmission bit rate in a statistical multiplexer

• US 7,418,007 B1
• Filed: 09/20/2000
• Issued: 08/26/2008
• Est. Priority Date: 09/20/2000
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Wu, Siu-Wai, Liu, Vincent, Casteloes, Michael, Lam, Rebecca, Stone, Robert J.
• Primary Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US09/666,901
• Time in Patent Office: 2,897 Days
• Field of Search: 370/282, 370/468, 370/465, 370535-538, 375/240, 375/240.1, 375/240.05, 375/240.24, 348/385.1
• US Class Current: 370/468
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• 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 21/2401 Monitoring of the client buffer

Abstract

A statistical multiplexer for coding and multiplexing multiple channels of digital television data, or multiple panels of HDTV digital television data. A bit rate need parameter is determined for each encoder in a stat mux group, and an encoding bit rate is allocated to each channel based on its need parameter. A transmission bit rate is allocated to each channel as a time-lagged version of its need parameter to minimize a rate mismatch between the output and the input of a decoder buffer. A packet processor checks for impending decoder buffer overflow or underflow events to set minimum and maximum limits on the transmission bit rate. Moreover, these limits are set based on whether a new transmission bit rate can be implemented before the decoding time stamp (DTS) of the current or next frame.

Claims

1. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and

wherein for at least one of the channels, when a next update of the allocated transmission bit rate can be implemented, following an implementation delay, before a decode time of a next picture, a maximum limit is set on the allocated transmission bit rate at a current time (CT) in proportion to a fullness of the modeled decoder buffer at a time (CT+delay), and in inverse proportion to a time period between (CT+delay) and the decode time.

2. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and

wherein for at least one of the channels, when a next update of the allocated transmission bit rate can not be implemented, following an implementation delay, before a decode time of a next picture, a maximum limit is set on the allocated transmission bit rate at a current time (CT) in proportion to a fullness of the modeled decoder buffer at a time (CT+delay), and in inverse proportion to a time period between (CT+delay) and a decode time of a picture that follows said next picture.

3. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and

wherein for at least one of the channels, when a next update of the allocated transmission bit rate can be implemented, following an implementation delay, before a decode time of the current picture, a minimum limit is set on the allocated transmission bit rate at a current time (CT) in proportion to a number of remaining bits of the current picture to transmit at a time (CT+delay), and in inverse proportion to a time period between (CT+delay) and the decode time.

4. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and, comprising the further step of;

for at least one of the channels, determining whether a current allocated transmission bit rate is sufficient to transmit a number of remaining bits of the current picture in a time period between a current time and a decode time of the current picture, and, if so, maintaining the current allocated transmission bit rate in a next update cycle thereof.

5. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and, comprising the further step of;

for at least one of the channels, forcing the allocated transmission bit rate to a maximum value in a next update cycle thereof when a current allocated transmission bit rate is not sufficient to transmit a number of remaining bits of the current picture in a time period between a current time and a decode time of the current picture.

6. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and,

wherein for at least one of the channels, when a next update of the allocated transmission bit rate can be implemented, following an implementation delay, before a decode time of a next picture, a maximum limit is set on the allocated transmission bit rate at a current time to avoid an overflow of the modeled decoder buffer at the decode time.

7. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and,

wherein for at least one of the channels, when a next update of the allocated transmission bit rate can not be implemented, following an implementation delay, before a decode time of a next picture, a maximum limit is set on the allocated transmission bit rate at a current time to avoid an overflow of the modeled decoder buffer at a decode time of a picture that follows said next picture.

8. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and,

wherein;

for at least one of the channels, when a next update of the allocated transmission bit rate can be implemented, following an implementation delay, before a decode time of the current picture, a minimum limit is set on the allocated transmission bit rate at a current time such that the current picture is completely transmitted before the decode time.

9. A method for processing a plurality of channels in a statistical multiplexer, comprising the steps of:

allocating an encoding bit rate for coding a current picture of each channel according to a bit rate need parameter thereof; and

for each channel, allocating a transmission bit rate for transmitting the current picture after encoding thereof, and providing a modeled decoder buffer that receives transmitted pictures therefrom;

wherein, for each channel, the transmission bit rate is based on the channel'"'"'s encoding bit rate, and is allocated following a system delay that follows the allocated encoding bit rate, to minimize a rate mismatch between an input and an output of the modeled decoder buffer, and,

wherein;

for at least one of the channels, when a next update of the allocated transmission bit rate can not be implemented, following an implementation delay, before a decode time of the current picture, a minimum limit on the allocated transmission bit rate at a current time is set to a maximum value to mitigate a potential underflow of the modeled decoder buffer.