Patent ID: 8526492

Claim:
Method for digitally encoding a picture sequence, wherein the pictures of said picture sequence are arranged in macroblocks containing pixel blocks and the pictures are encoded in intra and predictive and/or bi-predictive coding types denoted I, P and B, respectively, and wherein said pictures form groups of pictures and each group includes one anchor picture and several non-anchor pictures, wherein a current picture is called an ‘anchor picture’ if all pictures that were previously encoded before this current picture precede it in display order, and a current picture is called a ‘non-anchor picture’ if there exists at least one previously encoded picture that follows the current picture in display order, and wherein adaptively, for the purpose of overall bit rate control, a specific picture target number of bits is assigned to these coding types, and wherein said overall bit rate control includes a picture-layer rate control and a macroblock-layer rate control which macroblock-layer rate control selects macroblock quantization parameters, said method comprising the steps: assigning a target number of bits to anchor pictures but not assigning a target number of bits to non-anchor pictures; coding the macroblocks of said anchor pictures using macroblock-layer rate control by adaptive macroblock quantization parameters, and coding the macroblocks of said non-anchor pictures without macroblock-layer rate control by using fixed macroblock quantization parameters.