[FFmpeg-user] Correct fps value for h.264 stream

[Oliver Fromme]

Hello,

This is probably a very special problem, but maybe someone
has an answer ...

I've got an .m4v file that contains a h.264 video stream.
First thing I did is to convert it to .mkv because I can
handle Matroska files much better.  So far, so good.

The container format (both .m4v and .mkv) reports a frame
rate of 25 fps, but there is something wrong with the video
stream:  While mplayer plays the .mkv file fine, my media
runs riot on it.  It reports "-1 fps" (!), so I extracted
the video stream from the container for examination:  When
I run "mplayer -identify" on it, it reports 180000 fps, and
when I feed it into ffmpeg, it says 6203.12 fps.  Something
is definitely wrong with the stream.

My first attempt was to re-encode the video stream with
ffmpeg.  This worked fine, and now the media player can
play it, too.  But this is not satisfactory because the
re-encoding is not lossless.  So I tried various options
for ffmpeg with -vcodec copy, but it didn't work.  No
matter what I did, the h.264 stream didn't change (I
checked with MD5) and the fps information was still wrong.
I assume this is to be expected when using -vcodec copy,
but, well, I had to try anyway.

Just in case this information is useful, this is what I
get without any options except "-vcodec copy":

$ ffmpeg1 -i vstream-orig.h264 -vcodec copy vstream-new.h264
ffmpeg version 1.0.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Feb 16 2013 13:55:27 with gcc 4.2.1 (GCC) 20070831 patched [FreeBSD]
  configuration: --enable-x11grab --prefix=/usr/local --mandir=/usr/local/man --incdir=/usr/local/include/ffmpeg1 --libdir=/usr/local/lib/ffmpeg1 --shlibdir=/usr/local/lib/ffmpeg1 --datadir=/usr/local/share/ffmpeg1 --build-suffix=1 --progs-suffix=1 --enable-shared --enable-gpl --enable-postproc --enable-avfilter --enable-pthreads --enable-memalign-hack --disable-libstagefright-h264 --disable-libutvideo --cc=cc --extra-cflags='-msse -I/usr/local/include/vorbis -I/usr/local/include' --extra-ldflags='-L/usr/local/lib ' --extra-libs=-pthread --disable-debug --disable-libaacplus --disable-indev=alsa --disable-outdev=alsa --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-libass --disable-libcdio --disable-libcelt --enable-libfaac --disable-libfdk-aac --enable-fontconfig --enable-libfreetype --disable-frei0r --disable-gnutls --disable-libgsm --enable-libmp3lame --enable-libbluray --enable-libv4l2 --disable-libmodplug --disable-openal --enable-libopencv --enable-libo!
 penjpeg --disable-libpulse --disab  libavutil      51. 73.101 / 51. 73.101
  libavcodec     54. 59.100 / 54. 59.100
  libavformat    54. 29.104 / 54. 29.104
  libavdevice    54.  2.101 / 54.  2.101
  libavfilter     3. 17.100 /  3. 17.100
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[h264 @ 0x8094c1420] Stream #0: not enough frames to estimate rate; consider increasing probesize
[h264 @ 0x8094c1420] Estimating duration from bitrate, this may be inaccurate
Input #0, h264, from 'vstream-orig.h264':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264 (Main), yuv420p, 720x432 [SAR 64:45 DAR 64:27], 6203.12 fps, 90k tbr, 1200k tbn, 180k tbc
Output #0, h264, to 'vstream-new.h264':
  Metadata:
    encoder         : Lavf54.29.104
    Stream #0:0: Video: h264, yuv420p, 720x432 [SAR 64:45 DAR 64:27], q=2-31, 6203.12 fps, 90k tbn, 90k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36023 < 36024 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36024 < 36025 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36025 < 36026 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36026 < 36027 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36027 < 36028 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36028 < 36029 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36029 < 36030 invalid, clipping
[h264 @ 0x8094c1a20] st:0 PTS: -9223372036854775808 DTS: 36030 < 36031 invalid, clipping
... and so on ...

Those last lines reapeat A LOT.  I guess one line per frame.
When I add "-r 25" for both input and output, the only thing
that changes is this:

Output #0, h264, to 'vstream-new.h264':
  Metadata:
    encoder         : Lavf54.29.104
    Stream #0:0: Video: h264, yuv420p, 720x432 [SAR 64:45 DAR 64:27], q=2-31, 6203.12 fps, 90k tbn, 25 tbc

i.e. the tbc value changes from 90k to 25.  I still get the
"DTS invalid, clipping" lines, and it still says 6203.12 fps
for both input and output.  The next thing I tried was
to add "-vsync drop".  Now the "... clipping" lines were
gone, but of course the resulting file still didn't change.
I tried a lot of other options, but to no avail.

So, now my question is:  Is there a way to correct the
wrong fps setting in the h.264 stream without re-encoding
it, i.e. without loss?

Please let me know if I have to provide more output or if
you want me to try more commands.  Unfortunately I cannot
attach or upload the original file.

Best regards
   Oliver

--