Cosmetic nerd nit: > + av_log(avctx, AV_LOG_DEBUG, "large len %x \n", ((tagu & 0xff) << 16) | data); > + } else if (tag == 20) { > + av_log(avctx, AV_LOG_DEBUG, "Width %"PRIu16" \n", data); ^ You're logging a lot of trailing whitespace throughout most of your av_log() calls. Moritz