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)
committerReinhard Tartler <siretart@tauware.de>
Sat, 12 Jan 2013 16:59:40 +0000 (17:59 +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
(cherry picked from commit 706acb558a38eba633056773280155d66c2f4b24)

Conflicts:

libavcodec/h264.c

libavcodec/h264.c

index b866917..1c5b841 100644 (file)
@@ -4030,9 +4030,16 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size){
                 ff_h264_decode_seq_parameter_set(h);
             }
 
-            if (s->flags& CODEC_FLAG_LOW_DELAY ||
-                (h->sps.bitstream_restriction_flag && !h->sps.num_reorder_frames))
-                s->low_delay=1;
+            if (s->flags & CODEC_FLAG_LOW_DELAY ||
+                (h->sps.bitstream_restriction_flag &&
+                 !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;