libavcodec/mjpegdec.c:713: error: Uninitialized Value
  The value read from linesize[_] was never initialized.

libavcodec/mjpegdec.c:713:25: 
711.                         (h * mb_x + x) * 8) >> s->avctx->lowres);
712.                     if (s->interlaced && s->bottom_field)
713.                         ptr += linesize[c] >> 1;
                             ^
714. //av_log(NULL, AV_LOG_DEBUG, "%d %d %d %d %d %d %d %d \n", mb_x, mb_y, x, y, c, s->bottom_field, (v * mb_y + y) * 8, (h * mb_x + x) * 8);
715.                     if(!s->progressive)
