Answering my own question... I have not tested this but having manually read the code in the git history I'll try code up a fix for my theory:
looks like there is a bug in the commit 1a08758e7c4e14a9ea8d2fef6c33ad411b2d3c40 relating to the handling of ptr in decode_frame after decode_block is called, before this commit ptr would have been incremented for each line in the data window, now after the commit it is left at the start of the first included line rather than the line after the data window then the code sets the remaining lines to 0 and thus the whole image is over written. Kevin _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".