Transcoder Unit and Method

Abstract

A transcoder is provided that achieves lower complexity without picture quality loss. The transcoder may be either an open loop transcoder or a closed loop transcoder.

1 - 5 . (canceled) 
     
     
         6 : A transcoder for transcoding a first compressed bit stream having a first bit rate to a second compressed bit stream having a second bit rate, the transcoder comprising:
 a receiver configured to receive the first compressed bit stream having a motion vector and the first bit rate corresponding to a first quantization level;   a quantizer configured to quantize a stream of coefficients generated from the first compressed bit stream, at a second quantization level, for generating a stream of coefficients at the second quantization level; and   wherein the transcoder is configured to generate, based on the stream of coefficients at the second quantization level, the second compressed bit stream having the second hit rate, and wherein the second compressed bit stream includes the motion vector without modification.   
     
     
         7 : The transcoder of  claim 6 , wherein the transcoder further comprises a variable length coder that, based on the stream of coefficients at the second quantization level, generates the second bit stream having the second bit rate. 
     
     
         8 : The transcoder of  claim 6 , wherein each coefficient further comprises a discrete transform coefficient. 
     
     
         9 : A method of transcoding a first compressed bit stream having a first bit rate to a second compressed bit stream having a second bit rate, the method comprising:
 receiving the first compressed bit stream having a motion vector and the first bit rate corresponding to a first quantization level;   quantizing a stream of coefficients generated from the first compressed bit stream, at a second quantization level, for generating a stream of coefficients at the second quantization level; and   generating, based on the stream of coefficients at the second quantization level, the second compressed bit stream having the second bit rate, and wherein the second compressed bit stream includes the motion vector without modification.   
     
     
         10 : The method of  claim 9 , wherein the transcoder further comprises:
 generating, using a variable length coder, the second bit stream having the second bit rate based on the stream of coefficients at the second quantization level.   
     
     
         11 : The method of  claim 9 , wherein each coefficient further comprises a discrete transform coefficient.