Abstract: A picture coding method for transmission on a channel at a low bit rate and with a high error rate, for example, a channel with a bit rate less than 100 kbit/s and an error rate greater than 10?6, or even 10?4. The method uses motion estimation coding and divides the picture into a plurality of segments made up of macroblocks. At least for an edge macroblock of a segment, a motion estimation vector is allowed to extend into an adjacent segment. This is particularly advantageous for macroblocks situated top right of the segment if scanning for motion vector estimation is from left to right and top to bottom. Errors caused by estimating motion vectors within segments are avoided and the propagation of coding errors caused by splitting the picture into segments is limited.

Abstract: The invention relates to a picture coding method for transmission on a channel at a low bit rate and with a high error rate, typically a channel with a bit rate less than 100 kbit/s and an error rate greater than 10−6, or even 10−4. The method uses motion estimation coding and divides the picture into a plurality of segments made up of macroblocks. According to the invention, at least for an edge macroblock of a segment, a motion estimation vector is allowed to extend into an adjacent segment. This is particularly advantageous for macroblocks situated top right of the segment if scanning for motion vector estimation is from left to right and top to bottom. This solution avoids errors caused by estimating motion vectors within segments and limits the propagation of coding errors caused by splitting the picture into segments.

Abstract: The invention proposes a form of video source coding that is particularly suitable for transmission over a channel at a low bit rate and with a high error rate, such as a wireless transmission channel. It proposes to use block coding with motion prediction and employing a plurality of reference pictures. The reference pictures are subjected to block effect filtering. A reference picture is selected when coding a picture. By using a plurality of reference pictures, the invention limits transmission channel time propagation errors. Because the reference pictures are subjected to block effect filtering, transmission timing errors are corrected independently of intrinsic errors caused by block coding.