Algorithms for determining bitrate for a statistical multiplexing system to ensure stream alignment from encoders to the multiplexer

摘要

A statistical multiplexer (statmux) system for encoding and multiplexing multiple channels of digital television data is provided that limits dropped bits due to misalignment of bit rate allocations to the encoders. Without such a system, if for example an encoder is allotted 0 bits during a first time period and 20 kilobits during a second time period, if the encoder jumps ahead from the first period to the second time period allocation, the 20 kilobits could be output during the 0 bit output allocation time period. This can cause buffer overflow downstream if other encoders are outputting at their maximum rate. To limit such misalignment, a maximum percentage increase of an encoder's bitrate allocation is set from time period to time period based on a formula to prevent bits from being dropped when misalignment occurs.

主权项

1. A method for allocating bits in a statistical multiplexer comprising:
allocating a first bit rate allowed for the output of each of a plurality of encoders supplying a multiplexer during a first time period; determining a bit rate increase from the first bit rate for each of the encoders; and allocating a second bit rate allowable to each of the encoders for a second time period, subsequent to the first time period, wherein the second bit rate is limited by the determined bit rate increase, wherein misalignment of application of the second bit rate to a given one of the encoders can cause the second bit rate output to be provided in the first time period by the given encoder, and wherein the bit rate increase is determined so that when the misalignment of the second bit rate can occur for the second bit rate to be output in the first time period, the bit rate increase is set so that a total number of bits processed by the given encoder using the second rate does not exceed the encoder capacity that will cause bits to be dropped by the multiplexer.