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

[Michael Niedermayer]

On Fri, Dec 13, 2013 at 10:50:47AM -0800, Alex Sukhanov wrote:
> 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.

its only part of the file, sufficient to reproduce the problem


> 
> 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?

I think that the patch must not cause regressions before it can be
considered for git master

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The bravest are surely those who have the clearest vision
of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides
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