h264: Add check for invalid chroma_format_idc

Fixes a crash when FF_DEBUG_PICT_INFO is used.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

libavcodec/h264_ps.c

@@ -332,8 +332,12 @@ int ff_h264_decode_seq_parameter_set(H264Context *h){
 
     if(sps->profile_idc >= 100){ //high profile
         sps->chroma_format_idc= get_ue_golomb_31(&s->gb);
-        if(sps->chroma_format_idc == 3)
+        if(sps->chroma_format_idc > 3) {
+            av_log(h->s.avctx, AV_LOG_ERROR, "chroma_format_idc (%u) out of range\n", sps->chroma_format_idc);
+            return -1;
+        } else if(sps->chroma_format_idc == 3) {
             sps->residual_color_transform_flag = get_bits1(&s->gb);
+        }
         sps->bit_depth_luma   = get_ue_golomb(&s->gb) + 8;
         sps->bit_depth_chroma = get_ue_golomb(&s->gb) + 8;
         sps->transform_bypass = get_bits1(&s->gb);