[FFmpeg-devel] [PATCH 1/2] avformat/flvdec: add flv_ignore_prevtag option into flvdec

[Steven Liu]

dump the problem flv to problem_flv.flv.
liuqideMacBook-Pro:xxx liuqi$ dd if=~/Movies/Test/1.flv of=problem_flv.flv count=81920 bs=1
81920+0 records in
81920+0 records out
81920 bytes transferred in 0.767041 secs (106800 bytes/sec)

before this patch:
liuqideMacBook-Pro:xxx liuqi$ ./ffplay problem_flv.flv
ffplay version N-91141-gc24d247e2c Copyright (c) 2003-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.1)
  configuration: --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libspeex --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-version3 --cc='ccache gcc' --enable-nonfree --enable-videotoolbox --enable-opengl --enable-libxml2 --enable-libsrt
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 19.102 / 58. 19.102
  libavformat    58. 16.100 / 58. 16.100
  libavdevice    58.  4.100 / 58.  4.100
  libavfilter     7. 24.100 /  7. 24.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
[flv @ 0x7fcfe5821e00] Packet mismatch 355 352 352
problem_flv.flv: could not find codec parameters

after this patch:
liuqideMacBook-Pro:xxx liuqi$ ./ffplay -flv_ignore_prevtag 1 problem_flv.flv
ffplay version N-91141-gc24d247e2c Copyright (c) 2003-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.1)
  configuration: --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libspeex --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-version3 --cc='ccache gcc' --enable-nonfree --enable-videotoolbox --enable-opengl --enable-libxml2 --enable-libsrt
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 19.102 / 58. 19.102
  libavformat    58. 16.100 / 58. 16.100
  libavdevice    58.  4.100 / 58.  4.100
  libavfilter     7. 24.100 /  7. 24.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Input #0, flv, from 'problem_flv.flv':
  Metadata:
    fileSize        : 102128061
    audiochannels   : 2
    encoder         : obs-output module (libobs version 0.10.1)
  Duration: 00:05:09.60, start: 0.000000, bitrate: 2 kb/s
    Stream #0:0: Audio: aac (LC), 44100 Hz, stereo, fltp, 131 kb/s
    Stream #0:1: Video: h264 (High), yuv420p(tv, bt709, progressive), 960x600, 2560 kb/s, 30 fps, 30 tbr, 1k tbn, 60 tbc
[h264 @ 0x7fdf64122a00] Invalid NAL unit size (10375 > 1656).=0/0
[h264 @ 0x7fdf64122a00] Error splitting the input into NAL units.
   2.14 A-V: -0.013 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0

Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
---
 doc/demuxers.texi    | 3 +++
 libavformat/flvdec.c | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index 072918be28..5007e6339f 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -269,6 +269,9 @@ ffmpeg -f live_flv -i rtmp://<any.server>/anything/key ....
 @table @option
 @item -flv_metadata @var{bool}
 Allocate the streams according to the onMetaData array content.
+
+ at item -flv_ignore_prevtag @var{bool}
+Ignore the size of previous tag value.
 @end table
 
 @section gif
diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
index 34c3e08bad..861cf7c020 100644
--- a/libavformat/flvdec.c
+++ b/libavformat/flvdec.c
@@ -44,6 +44,7 @@
 typedef struct FLVContext {
     const AVClass *class; ///< Class for private options.
     int trust_metadata;   ///< configure streams according onMetaData
+    int trust_datasize;   ///< trust data size of FLVTag
     int wrong_dts;        ///< wrong dts due to negative cts
     uint8_t *new_extradata[FLV_STREAM_TYPE_NB];
     int new_extradata_size[FLV_STREAM_TYPE_NB];
@@ -1252,6 +1253,7 @@ retry_duration:
 
 leave:
     last = avio_rb32(s->pb);
+    if (!flv->trust_datasize) {
     if (last != orig_size + 11 && last != orig_size + 10 &&
         !avio_feof(s->pb) &&
         (last != orig_size || !last) && last != flv->sum_flv_tag_size &&
@@ -1264,6 +1266,7 @@ leave:
             goto retry;
         }
     }
+    }
     return ret;
 }
 
@@ -1279,6 +1282,7 @@ static int flv_read_seek(AVFormatContext *s, int stream_index,
 #define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     { "flv_metadata", "Allocate streams according to the onMetaData array", OFFSET(trust_metadata), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VD },
+    { "flv_ignore_prevtag", "Ignore the Size of previous tag", OFFSET(trust_datasize), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VD },
     { "missing_streams", "", OFFSET(missing_streams), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 0xFF, VD | AV_OPT_FLAG_EXPORT | AV_OPT_FLAG_READONLY },
     { NULL }
 };
-- 
2.15.1