[FFmpeg-user] Encode flv video with no audio

[David Bengoa]

Hi,

I'm making an application that needs to convert videos to webm or mp4, 
it works great with all videos I've tried, but it fails if I use a flv 
file with no audio channels.

A example command (not the actual flags I use, but fails anyway):

|$ ffmpeg -i 0986229665-339108519108-86498841039-6078455325.flv out.webm
ffmpeg version 0.7.3-4:0.7.3-0ubuntu0.11.10.1, Copyright (c) 2000-2011 the Libav developers
   built on Jan  4 2012 16:08:51 with gcc 4.6.1
   configuration: --extra-version='4:0.7.3-0ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
   WARNING: library configuration mismatch
   avutil      configuration: --extra-version='4:0.7.3ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-libopenjpeg --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdirac --enable-libmp3lame --enable-librtmp --enable-libx264 --enable-libxvid --enable-libvo-aacenc --enable-version3 --enable-libvo-amrwbenc --enable-version3 --enable-libdc1394 --enable-shared --disable-static
   avcodec     configuration: --extra-version='4:0.7.3ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-libopenjpeg --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdirac --enable-libmp3lame --enable-librtmp --enable-libx264 --enable-libxvid --enable-libvo-aacenc --enable-version3 --enable-libvo-amrwbenc --enable-version3 --enable-libdc1394 --enable-shared --disable-static
   libavutil    51.  7. 0 / 51.  7. 0
   libavcodec   53.  6. 0 / 53.  6. 0
   libavformat  53.  3. 0 / 53.  3. 0
   libavdevice  53.  0. 0 / 53.  0. 0
   libavfilter   2.  4. 0 /  2.  4. 0
   libswscale    2.  0. 0 /  2.  0. 0
   libpostproc  52.  0. 0 / 52.  0. 0
[flv @ 0x2184560] Could not find codec parameters (Audio: [0][0][0][0] / 0x0000, 0 channels)
[flv @ 0x2184560] Estimating duration from bitrate, this may be inaccurate
Input #0, flv, from '0986229665-339108519108-86498841039-6078455325.flv':
   Metadata:
     audiocodecid    : -1
     server          : Red5 Server 1.0.0 RC1 $Rev: 4193 $
     duration        : 3
     canSeekToEnd    : true
     videocodecid    : 2
   Duration: 00:00:03.02, start: 0.000000, bitrate: N/A
     Stream #0.0: Video: flv, yuv420p, 640x362, 1k tbr, 1k tbn, 1k tbc
     Stream #0.1: Audio: [0][0][0][0] / 0x0000, 0 channels
Incompatible sample format '(null)' for codec 'libvorbis', auto-selecting format 's16'
[buffer @ 0x21852c0] w:640 h:362 pixfmt:yuv420p
[libvpx @ 0x2184040] v0.9.6
[libvorbis @ 0x2185ee0] oggvorbis_encode_init: init_encoder failed
Output #0, webm, to 'out.webm':
     Stream #0.0: Video: libvpx, yuv420p, 640x362, q=2-31, 200 kb/s, 90k tbn, 1k tbc
     Stream #0.1: Audio: libvorbis, 0 channels, s16, 64 kb/s
Stream mapping:
   Stream #0.0 -> #0.0
   Stream #0.1 -> #0.1
Error while opening encoder for output stream #0.1 - maybe incorrect parameters such as bit_rate, rate, width or height
|

If I pass the -an option, it works, but I can't do that because then all 
videos wouldn't have audio.

Any ideas?

-- 
David Bengoa http://dvdbng.com