[FFmpeg-cvslog] avformat/flvdec: Try to support some concatenated flv files

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jan  3 01:08:31 2019 +0100| [b559c58a03f88dcbf1e61875bb494743d4c6d081] | committer: Michael Niedermayer

avformat/flvdec: Try to support some concatenated flv files

Fixes: discont.flv

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b559c58a03f88dcbf1e61875bb494743d4c6d081
---

 libavformat/flvdec.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
index 4b9f46902b..972e333313 100644
--- a/libavformat/flvdec.c
+++ b/libavformat/flvdec.c
@@ -72,6 +72,9 @@ typedef struct FLVContext {
     int64_t *keyframe_filepositions;
     int missing_streams;
     AVRational framerate;
+    int64_t last_ts;
+    int64_t time_offset;
+    int64_t time_pos;
 } FLVContext;
 
 static int probe(AVProbeData *p, int live)
@@ -917,6 +920,18 @@ static int resync(AVFormatContext *s)
         flv->resync_buffer[j ] =
         flv->resync_buffer[j1] = avio_r8(s->pb);
 
+        if (i >= 8 && pos) {
+            uint8_t *d = flv->resync_buffer + j1 - 8;
+            if (d[0] == 'F' &&
+                d[1] == 'L' &&
+                d[2] == 'V' &&
+                d[3] < 5 && d[5] == 0) {
+                av_log(s, AV_LOG_WARNING, "Concatenated FLV detected, might fail to demux, decode and seek %"PRId64"\n", flv->last_ts);
+                flv->time_offset = flv->last_ts + 1;
+                flv->time_pos    = avio_tell(s->pb);
+            }
+        }
+
         if (i > 22) {
             unsigned lsize2 = AV_RB32(flv->resync_buffer + j1 - 4);
             if (lsize2 >= 11 && lsize2 + 8LL < FFMIN(i, RESYNC_BUFFER_SIZE)) {
@@ -1072,6 +1087,10 @@ skip:
         }
         av_log(s, AV_LOG_TRACE, "%d %X %d \n", stream_type, flags, st->discard);
 
+        if (flv->time_pos <= pos) {
+            dts += flv->time_offset;
+        }
+
         if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
             ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY ||
               stream_type == FLV_STREAM_TYPE_AUDIO))
@@ -1282,6 +1301,10 @@ leave:
             }
         }
     }
+
+    if (ret >= 0)
+        flv->last_ts = pkt->dts;
+
     return ret;
 }