[FFmpeg-devel] [PATCH] Enable parser in FLV demuxer for H264 codec

[Alex Sukhanov]

On Thu, Dec 12, 2013 at 7:37 PM, Alex Sukhanov <alx.sukhanov at gmail.com>wrote:

>
>
>
> On Thu, Dec 12, 2013 at 6:09 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
>
>> On Thu, Dec 12, 2013 at 03:10:10PM -0800, Alex Sukhanov wrote:
>> > ---
>> >  libavformat/flvdec.c | 1 +
>> >  1 file changed, 1 insertion(+)
>> >
>> > diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
>> > index 1024001..4401652 100644
>> > --- a/libavformat/flvdec.c
>> > +++ b/libavformat/flvdec.c
>> > @@ -256,6 +256,7 @@ static int flv_set_video_codec(AVFormatContext *s,
>> AVStream *vstream,
>> >          return 1;     // 1 byte body size adjustment for
>> flv_read_packet()
>> >      case FLV_CODECID_H264:
>> >          vcodec->codec_id = AV_CODEC_ID_H264;
>> > +        vstream->need_parsing = AVSTREAM_PARSE_HEADERS;
>> >          return 3;     // not 4, reading packet type will consume one
>> byte
>> >      case FLV_CODECID_MPEG4:
>> >          vcodec->codec_id = AV_CODEC_ID_MPEG4;
>>
>> breaks
>> ffmpeg -i Enigma_Principles_of_Lust.flv test.flv
>>
>> before the patch:
>> frame= 6300 fps=1441 q=31.0 Lsize=    7266kB time=00:03:30.65 bitrate=
>> 282.6kbits/s
>> after the patch
>> frame= 4531 fps=1180 q=9.8 Lsize=    6987kB time=00:03:30.65 bitrate=
>> 271.7kbits/s dup=0 drop=1769
>>
>> [....]
>>
>> --
>> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>>
>> The misfortune of the wise is better than the prosperity of the fool.
>> -- Epicurus
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
>>
>
> Hi Michael,
>
> I tested ffmpeg with and without my patch on following video:
>
> Input #0, flv, from '/home/asukhanov/Work/clips/flv/gangman.flv':
>   Metadata:
>     encoder         : Google
>   Duration: 00:04:12.31, start: 0.000000, bitrate: 887 kb/s
>     Stream #0:0: Video: h264 (Main), yuv420p, 640x360, 24.42 fps, 23.98
> tbr, 1k tbn, 47.95 tbc
>     Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp, 128 kb/s
>
> Which is just a first video I grabbed:
> http://www.youtube.com/watch?v=9bZkp7q19f0
>
> My results are:
>
> before:
> *frame= 6046 fps=418 q=31.0 Lsize=   18328kB time=00:04:12.31 bitrate=
> 595.1kbits/s    *
> video:14139kB audio:3943kB subtitle:0 global headers:0kB muxing overhead
> 1.358910%
>
> after:
> *frame= 6046 fps=416 q=31.0 Lsize=   18328kB time=00:04:12.31 bitrate=
> 595.1kbits/s  *
> video:14139kB audio:3943kB subtitle:0 global headers:0kB muxing overhead
> 1.358910%
>
> Configuration:
> ./configure --enable-gpl --enable-libass --enable-libfaac
> --enable-libfdk-aac --enable-libmp3lame   --enable-libopencore-amrnb
> --enable-libopencore-amrwb --enable-librtmp --enable-libtheora
> --enable-libvorbis --enable-x11grab --enable-libx264 --enable-nonfree
> --enable-version3
>
>
> May I ask you to share your FLV file with me, or verify that you ran the
> same command line - probably it was not the same in your case, because
> quantizer is different in your case: 31 vs 9 That could affect FPS much
> more seriously than parsing headers in Demuxer.
>
> Thank you
>


Hi Michael,

Sorry, yesterday I missed that you sent me your FLV file. Thanks a lot for
it.
I tried to play it with ffplay and mplayer and it seems to me source file
is corrupted:

[h264 @ 0x7f2cf01a30a0] AVC: nal size 21839893
    Last message repeated 1 times
[h264 @ 0x7f2cf01a30a0] no frame!
[h264 @ 0x7f2cf01a30a0] AVC: nal size 2771    1KB sq=    0B f=0/52
    Last message repeated 1 times
[h264 @ 0x7f2cf01a30a0] no frame!
  20.71 A-V:  0.038 fd=   5 aq=    0KB vq=    0KB sq=    0B f=0/55

Both players play first 10 seconds of video and then just stuck.

But I also tried to transcode it with and without my patch:

before:
frame=  350 fps=0.0 q=17.2 Lsize=     590kB time=00:00:11.74 bitrate=
411.2kbits/s
video:485kB audio:92kB subtitle:0 global headers:0kB muxing overhead
2.279257%

after:
frame=  295 fps=0.0 q=18.1 Lsize=     539kB time=00:00:11.70 bitrate=
377.3kbits/s dup=0 drop=55
video:435kB audio:92kB subtitle:0 global headers:0kB muxing overhead
2.331014%


My opinion is that it's safe to apply this patch. What do you think?