Picture information conversion method and apparatus

A picture information conversion device which is fed with the first compressed picture information of CBR (constant bitrate) or VBR (variable bitrate) as a first bitrate and which outputs the second compressed picture information at CBR as a second bitrate, said first compressed picture information being picture signals compression-coded in terms of a GOP (group of pictures) made up of at least one picture, as a unit, said picture information conversion device comprising:

• first storage means for storing N frames of the input first compressed picture information;
• compressed picture information analysis means for analyzing the structure of the picture type of the GOP of the first compressed picture information input to said first storage means;
• second storage means for storing the analysis result information as the result of analysis by said compressed picture information analysis means, supplied by said compressed picture information analysis means;
• pseudo GOP generating means for generating a pseudo GOP, based on said N frames stored in said first storage means and on said analysis result information stored in said second storage means, said pseudo GOP predicting the picture type of the entire GOP including said N frames of said first compressed picture information;
• code volume allocation means for allocating a pre-set code volume to each picture of the pseudo GOP generated by said pseudo GOP generating means so that the output second compressed picture information will be at said second bitrate;
• wherein said code volume allocation means allocates a smaller code volume and a larger code volume to leading side pictures and to trailing side pictures of said pseudo GOP generated by said pseudo GOP generating means, respectively.