extracting h264 raw video stream from mp4 or flv with ffmpeg generate an invalid stream

Question

I'm trying to extract the video stream from an mp4 or flv h264 video (youtube video) using ffmpeg. The original video (test.flv) play without trouble with ffplay , ffprobe gives an error as follow:

ffprobe version N-55515-gbbbd959 Copyright (c) 2007-2013 the FFmpeg developers
built on Aug 13 2013 18:06:32 with gcc 4.7.3 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
eex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-
amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --
enable-libxvid --enable-zlib
  libavutil      52. 42.100 / 52. 42.100
  libavcodec     55. 27.100 / 55. 27.100
  libavformat    55. 13.102 / 55. 13.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 82.100 /  3. 82.100
  libswscale      2.  4.100 /  2.  4.100
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
[flv @ 000000000031ea80] Stream discovered after head already parsed
Input #0, flv, from 'test.flv':
  Metadata:
    starttime       : 0
    totalduration   : 142
    totaldatarate   : 692
    bytelength      : 12286492
    canseekontime   : true
    sourcedata      : B42B95507HH1381414522145462
    purl            :
    pmsg            :
  Duration: 00:02:22.02, start: 0.000000, bitrate: 692 kb/s
    Stream #0:0: Video: h264 (Main), yuv420p, 640x268, 568 kb/s, 23.98 tbr, 1k t
bn, 47.95 tbc
    Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp, 131 kb/s
    Stream #0:2: Data: none
Unsupported codec with id 0 for input stream 2

to get rid of the extra streams ( I only needs the video) I used the following ffmpeg command line:

ffmpeg -i test.flv -map 0:0 -vcodec copy -an -f h264 test.h264

The new stream is unreadable by any player including ffplay and gives an error with ffprobe : test.h264: Invalid data found when processing inputq= 0B f=0/0

Any body have an idea about what am I doing wrong?

I also tried simpler youtube command line:

ffmpeg -i test.flv -vcodec copy -an test.h264

if I use another format (avi for example):

ffmpeg -i test.flv -vcodec copy -an test.avi

the output video is valid.

If I transcode the video

ffmpeg -i test.flv -an test.h264

the output is also valid

Any suggestions?

Answer 1

To extract a raw video from an MP4 or FLV container you should specify the -bsf:v h264_mp4toannexb or -vbfs h264_mp4toannexb option.

ffmpeg -i test.flv -vcodec copy -an -bsf:v h264_mp4toannexb test.h264

The raw stream without H264 Annex B / NAL cannot be decode by player. With that option ffmpeg perform a simple "mux" of each h264 sample in a NAL unit.