Statistical remultiplexing with bandwidth allocation among different transcoding channels

Abstract

An efficient statistical remultiplexer for processing a number of channels that include video data. In one aspect, transcoding of the video data is delayed while statistical information is obtained from the data. Bit rate need parameters for the data are determined based on the statistical information, and the video data is transcoded based on the respective bit rate need parameters following the delay. In another aspect, a transcoding bit rate for video frames is updated a plurality of times at successive intervals to allow a closer monitoring of the bit rate. Minimum and maximum bounds for the transcoding bit rate, e.g., for buffer overflow and underflow protection, are also updated in each interval.

1 . A method for processing data in a statistical remultiplexer that receives a plurality of channels of encoded data, comprising: 
 recovering video frames from the encoded data;    storing the video frames in a lookahead buffer in order to delay transcoding of the video frames while obtaining statistical information therefrom;    determining respective bit rate need parameters for the video frames according to the obtained statistical information thereof; and    transcoding the respective video frames in accordance with the respective bit rate need parameters following the delaying thereof.    
     
     
         2 . The method of  claim 1 , further comprising: 
 storing the respective bit rate need parameters in a storage device; and    recovering the bit rate need parameters from the storage device for the respective video frames for use in transcoding thereof.    
     
     
         3 . The method of  claim 1 , wherein: 
 the statistical information of a respective video frame that is used for determining the respective bit rate need parameter comprises an average quantizer scale value thereof.    
     
     
         4 . The method of  claim 1 , wherein: 
 the statistical information of a respective video frame that is used for determining the respective bit rate need parameter comprises a number of bits therein.    
     
     
         5 . The method of  claim 1 , wherein: 
 the statistical information of a respective video frame that is used for determining the respective bit rate need parameter comprises an average bit rate associated therewith.    
     
     
         6 . The method of  claim 1 , wherein: 
 the statistical information of a respective video frame that is used for determining the respective bit rate need parameter comprises a number of bits in macroblocks therein.    
     
     
         7 . The method of  claim 1 , wherein: 
 the statistical information of a respective video frame that is used for determining the respective bit rate need parameter comprises a macroblock resolution thereof.    
     
     
         8 . A statistical remultiplexer that receives a plurality of channels of encoded data, comprising: 
 means for recovering video frames from the encoded data;    means for storing the video frames in order to delay transcoding of the video frames while obtaining statistical information therefrom;    means for determining respective bit rate need parameters for the video frames according to the obtained statistical information thereof; and    means for transcoding the respective video frames in accordance with the respective bit rate need parameters following the delaying thereof.    
     
     
         9 . A method for processing data in a statistical remultiplexer that receives a plurality of channels comprising encoded video frames, comprising: 
 updating a transcoding bit rate for at least a particular video frame a plurality of times at successive intervals as transcoding thereof progresses;    bounding the updated transcoding bit rates by at least one of minimum and maximum levels that are also updated in each of the successive intervals to provide corresponding bounded and updated transcoding bit rates;    allocating the bounded and updated transcoding bit rates for transcoding corresponding portions of the particular video frame in the successive intervals;    computing a target frame size for the particular video frame that indicates an amount of data that is expected to result from transcoding the particular video frame; wherein:    the target frame size is bounded by at least one of minimum and maximum predicted values that are updated in the successive intervals;    the transcoding bit rate for the particular video frame in the successive intervals is determined in accordance with the target frame size.    
     
     
         10 . The method of  claim 9 , wherein: 
 the successive intervals are periodic.    
     
     
         11 . The method of  claim 9 , wherein: 
 the updated transcoding bit rates are bounded by both minimum and maximum levels that are updated in each of the successive intervals to provide the corresponding bounded and updated transcoding bit rates.    
     
     
         12 . The method of  claim 9 , wherein: 
 video frames whose associated target frame size is greater than a number of pre-transcoding bits thereof bypass transcoding.    
     
     
         13 . The method of  claim 9 , wherein: 
 video frames whose associated target frame size is greater than a number of pre-transcoding bits thereof by a predetermined difference bypass transcoding.    
     
     
         14 . The method of  claim 9 , further comprising: 
 allocating a variable amount of transmission bandwidth for passthrough data of the plurality of channels; and    adjusting an amount of transmission bandwidth for transcoding the video frames in the plurality of channels in accordance with said allocating step.    
     
     
         15 . The method of  claim 9 , wherein: 
 the statistical remultiplexer outputs a transport stream comprising a plurality of statistical remultiplexing groups of channels; and    respective portions of a total available transmission bandwidth are used to configure respective ones of the statistical remultiplexing groups.    
     
     
         16 . The method of  claim 9 , further comprising: 
 delaying the updated and bounded transcoding bit rates in the successive intervals according to a delay associated with an associated transcoding engine; and    allocating transmission bit rates in accordance with the updated and bounded transcoding bit rates after the delaying thereof for transmitting the particular video frame after transcoding thereof.    
     
     
         17 . The method of  claim 16 , further comprising: 
 providing a number of packets of the particular video frame after transcoding thereof to a multiplexer for multiplexing with packets of at least one other of the channels in accordance with the allocated transmission bit rates.    
     
     
         18 . The method of  claim 9 , wherein: 
 the at least one of minimum and maximum predicted values are determined in accordance with a current fullness of an associated transcoding engine buffer.    
     
     
         19 . The method of  claim 9 , wherein: 
 the at least one of minimum and maximum predicted values are determined so as to protect an associated decoder buffer from underflow or overflow.    
     
     
         20 . The method of  claim 9 , further comprising: 
 estimating a time for transmitting at least one packet comprising transcoded data of the particular video frame according to the target frame size.    
     
     
         21 . The method of  claim 9 , further comprising: 
 estimating a time for inserting clock reference data into at least one packet comprising transcoded data of the particular video frame according to the target frame size.    
     
     
         22 . A statistical remultiplexer that receives a plurality of channels comprising encoded video frames, comprising: 
 means for updating a transcoding bit rate for at least a particular video frame a plurality of times at successive intervals as transcoding thereof progresses;    means for bounding the updated transcoding bit rates by at least one of minimum and maximum levels that are also updated in each of the successive intervals to provide corresponding bounded and updated transcoding bit rates; and    means for allocating the bounded and updated transcoding bit rates for transcoding corresponding portions of the particular video frame in the successive intervals;    means for computing a target frame size for the particular video frame that indicates an amount of data that is expected to result from transcoding the particular video frame; wherein: 
 the target frame size is bounded by at least one of minimum and maximum predicted values that are updated in the successive intervals;  
 the transcoding bit rate for the particular video frame in the successive intervals is determined in accordance with the target frame size.  
   
     
     
         23 . A statistical remultiplexer in accordance with  claim 22 , wherein: 
 video frames whose associated target frame size is greater than a number of pre-transcoding bits thereof by a predetermined difference bypass transcoding.    
     
     
         24 . A statistical remultiplexer in accordance with  claim 22 , further comprising: 
 means for estimating a time for inserting clock reference data into at least one packet comprising transcoded data of the particular video frame according to the target frame size.