Image coded data re-encoding apparatus

Abstract

An image coded data re-encoding apparatus ( 30 ) which generates in an image coded data analyzer ( 310 ) coded data after signal processing ( 221 ) by performing a first digital signal processing on first image coded data ( 220 ), supplies an image coded data synthesizer ( 320 ) with the coded data after signal processing ( 221 ) and multiple signals ( 222 ) associated with the first image coded data, and generates in the image coded data synthesizer ( 320 ) a second image coded data ( 240 ) by performing on the coded data after signal processing ( 221 ) a second digital signal processing based on multiple signals ( 222 ). The second image coded data is generated without once decoding the first image coded data. This makes it possible to prevent degradation in image quality, delay involved in the transform and an increase of the device size.

What is claimed is:  
     
         1 . An image coded data re-encoding apparatus which receives a first image coded data generated by a coding processor performing coding of a digital input image signal, and which generates a second image coded data by performing a digital signal processing on said first image coded data, said image coded data re-encoding apparatus comprising: 
 an image coded data analyzer for generating coded data after signal processing by performing a first digital signal processing on said first image coded data; and    an image coded data synthesizer for generating said second image coded data by performing on said coded data after signal processing a second digital signal processing based on multiple signals associated with said first image coded data by using said coded data after signal processing output from said image coded data analyzer and said multiple signals.    
     
     
         2 . The image coded data re-encoding apparatus as claimed in  claim 1 , wherein 
 said image coded data analyzer extracts said multiple signals in the course of generating said coded data after signal processing by performing said first digital signal processing on said first image coded data, and    said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing based on said multiple signals by using said coded data after signal processing and said multiple signals which are output from said image coded data analyzer.    
     
     
         3 . The image coded data re-encoding apparatus as claimed in  claim 1 , wherein 
 said image coded data re-encoding apparatus further comprises a separator for separating from said first image coded data said multiple signals which have been externally combined with said first image coded data and cannot be extracted from said first image coded data in said first digital signal processing for generating said coded data after signal processing, and    said image coded data synthesizer generates said second image coded data by performing on said coded data after signal processing said second digital signal processing based on said multiple signals by using said coded data after signal processing output from said image coded data analyzer and said multiple signals output from said separator.    
     
     
         4 . The image coded data re-encoding apparatus as claimed in  claim 1 , wherein 
 said image coded data analyzer decodes said first image coded data by performing said first digital signal processing on said first image coded data to generate decoded image data as said coded data after signal processing,    said image coded data re-encoding apparatus further comprises an information extractor/estimator for extracting or estimating said multiple signals needed for said second digital signal processing from said coded data after signal processing generated by said image coded data analyzer, and    said image coded data synthesizer generates said second image coded data by performing on said coded data after signal processing said second digital signal processing based on said multiple signals by using said coded data after signal processing output from said image coded data analyzer and said multiple signals output from said information extractor/estimator.    
     
     
         5 . The image coded data re-encoding apparatus as claimed in any one of claims  1 - 4 , wherein said image coded data synthesizer generates said second image coded data with a data amount different from a data amount of said first image coded data input to said image coded data analyzer, when said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing from said image coded data analyzer in response to said multiple signals from said image coded data analyzer.  
     
     
         6 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for deleting part of said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, and for correcting said transform coefficients or quantization indices in accordance with a ratio of amounts of data to be transformed.    
     
     
         7 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for deleting part of said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, and are weighted in accordance with relationships between said transform coefficients or quantization indices and their neighboring transform coefficients or quantization indices.    
     
     
         8 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for adding, to said transform coefficients or quantization indices which are extracted by said image coded data analyzer, new transform coefficients or quantization indices after correcting said new transform coefficients or quantization indices in accordance with a ratio of amounts of data to be transformed.    
     
     
         9 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for adding, to said transform coefficients or quantization indices which are extracted by said image coded data analyzer, new transform coefficients or quantization indices after predicting transform coefficients or quantization indices including said new transform coefficients or quantization indices and their neighboring transform coefficients or quantization indices.    
     
     
         10 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and generates a coding parameter designating a picture type of a current image to be processed, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for increasing a ratio of deletion of said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, if said coding parameter designating the picture type indicates, when decision is made whether or not said current image to be processed is used for prediction in future coding, that said picture type is not used for the prediction in the future coding.    
     
     
         11 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and generates a coding parameter designating a picture type of a current image to be processed, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for decreasing a ratio of deletion of said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, if said coding parameter designating the picture type indicates, when decision is made whether or not said current image to be processed is used for prediction in future coding, that said picture type is used for the prediction in the future coding.    
     
     
         12 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and generates a coding parameter designating a picture type of a current image to be processed, and a coding parameter designating a predictive type of an image block of the current image, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for increasing a ratio of deletion of said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, if said coding parameter designating the predictive type of said image block indicates, when decision is made whether a current image to be processed is used for prediction in future coding by using the coding parameters generated by said image coded data analyzer, that said image block is not used for the prediction in the future coding, even if said coding parameter designating the picture type indicates that the picture type is used for the prediction in the future coding.    
     
     
         13 . The image coded data re-encoding apparatus as claimed in any one of claims  1 - 4 , wherein said image coded data synthesizer generates said second image coded data whose decoding procedure differs from a decoding procedure of said first image coded data input to said image coded data analyzer, when said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing from said image coded data analyzer in response to said multiple signals from said image coded data analyzer.  
     
     
         14 . The image coded data re-encoding apparatus as claimed in  claim 13 , wherein 
 said image coded data analyzer extracts from said first image coded data various types of coding parameters with an expression form in said decoding procedure of said first image coded data, and    said image coded data re-encoding apparatus further comprises a coding parameter corrector/transformer for correcting and transforming said expression form of said various types of coding parameters, which are extracted by said image coded data analyzer, from said expression form in said decoding procedure of said first image coded data to an expression form in the decoding procedure of said second image coded data.    
     
     
         15 . The image coded data re-encoding apparatus as claimed in any one of claims  1 - 4 , wherein said image coded data synthesizer generates said second image coded data including an image signal whose image size differs in time or space from an image size of an image signal included in said first image coded data input to said image coded data analyzer, when said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing from said image coded data analyzer in response to said multiple signals from said image coded data analyzer.  
     
     
         16 . The image coded data re-encoding apparatus as claimed in  claim 15 , 
 wherein said image coded data analyzer extracts transform coefficients or quantization indices, which are inversely quantized, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for changing an amount of said transform coefficients or quantization indices extracted by said image coded data analyzer, and for correcting said transform coefficients or quantization indices, which are extracted by said image coded data analyzer, in accordance with a ratio of the image sizes to be transformed.    
     
     
         17 . The image coded data re-encoding apparatus as claimed in  claim 15 , 
 wherein said image coded data analyzer extracts motion vectors used for motion compensation, and    wherein said image coded data re-encoding apparatus further comprises a coefficient deletion/addition/correction portion for correcting dimension of said motion vectors extracted by said image coded data analyzer in accordance with a ratio of the image sizes to be transformed.    
     
     
         18 . The image coded data re-encoding apparatus as claimed in any one of claims  1 - 4 , wherein said image coded data synthesizer generates said second image coded data including an image signal whose sequence differs from a sequence of an image signal included in said first image coded data input to said image coded data analyzer, when said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing from said image coded data analyzer in response to said multiple signals from said image coded data analyzer.  
     
     
         19 . The image coded data re-encoding apparatus as claimed in  claim 18 , 
 wherein said image coded data analyzer extracts motion vectors used for motion compensation, and    wherein said image coded data re-encoding apparatus further comprises a motion searcher for estimating dimension of said motion vectors extracted by said image coded data analyzer in accordance with said sequence of the image signals to be transformed.    
     
     
         20 . The image coded data re-encoding apparatus as claimed in any one of claims  1 - 4 , wherein said image coded data synthesizer generates said second image coded data whose decoded image signal includes a number of frames per unit time different from a number of frames per unit time of a decoded image signal of said first image coded data input to said image coded data analyzer, when said image coded data synthesizer generates said second image coded data by performing said second digital signal processing on said coded data after signal processing from said image coded data analyzer in response to said multiple signals from said image coded data analyzer.  
     
     
         21 . The image coded data re-encoding apparatus as claimed in  claim 5 , 
 wherein said image coded data analyzer generates as the coded data after signal processing a decoded image obtained by decoding said first image coded data,    wherein said image coded data re-encoding apparatus further comprises a quantization estimator for estimating, from said decoded image output from said image coded data analyzer, quantization parameters obtained in the course of generating said first image coded data, and    wherein said image coded data synthesizer generates said second image coded data by using said quantization parameters estimated by said quantization estimator.