libavcodec/mjpegdec.c:845: error: Uninitialized Value
  The value read from data[_] was never initialized.

libavcodec/mjpegdec.c:845:21: 
843.                     if(s->interlaced && s->bottom_field)
844.                         block_offset += linesize[c] >> 1;
845.                     ptr = data[c] + block_offset;
                         ^
846.                     if(!s->progressive) {
847.                         if (copy_mb) {
