h264: enable low delay only if no delayed frames were seen
authorJanne Grunau <janne-libav@jannau.net>
Fri, 16 Nov 2012 13:31:09 +0000 (14:31 +0100)
committerJanne Grunau <janne-libav@jannau.net>
Mon, 26 Nov 2012 09:25:39 +0000 (10:25 +0100)
Dropping frames is undesirable but that is the only way by which the
decoder could return to low delay mode. Instead emit a warning and
continue with delayed frames.
Fixes a crash in fuzzed sample nasa-8s2.ts_s20033 caused by a larger
than expected has_b_frames value. Low delay keeps getting re-enabled
from a presumely broken SPS.

CC: libav-stable@libav.org
libavcodec/h264.c

index f45c572..658d865 100644 (file)
@@ -3867,8 +3867,14 @@ again:
 
                 if (s->flags & CODEC_FLAG_LOW_DELAY ||
                     (h->sps.bitstream_restriction_flag &&
-                     !h->sps.num_reorder_frames))
-                    s->low_delay = 1;
+                     !h->sps.num_reorder_frames)) {
+                    if (s->avctx->has_b_frames > 1 || h->delayed_pic[0])
+                        av_log(avctx, AV_LOG_WARNING, "Delayed frames seen "
+                               "reenabling low delay requires a codec "
+                               "flush.\n");
+                        else
+                            s->low_delay = 1;
+                }
 
                 if (avctx->has_b_frames < 2)
                     avctx->has_b_frames = !s->low_delay;