Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

I am doing a conversion of mp4 to flv on a GUI less server where I have only SSH access.( I tried winff and X forwarding that had hanged while doing this conversion so winff is not possible for me)

I do not have any idea of the codecs,bitrate of this mp4 video. Some one had converted from an m4v to mp4 and then uploaded this on the server.

When I tried converting on command line as follows

ffmpeg -i stats_estimation.mp4 out.flv
FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --extra-version=4:0.5.1-1ubuntu1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 1 / 52.20. 1
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar  4 2010 12:41:55, gcc: 4.4.3

Seems stream 0 codec frame rate differs from container frame rate: 29.94 (5000/167) -> 44.92 (539/12)
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'stats_estimation.mp4':
  Duration: 02:47:05.56, start: 0.000000, bitrate: 237 kb/s
    Stream #0.0(eng): Video: h264, yuv420p, 320x240, 44.92 tbr, 14.97 tbn, 29.94 tbc
    Stream #0.1(eng): Audio: aac, 32000 Hz, stereo, s16
Output #0, flv, to 'out.flv':
    Stream #0.0(eng): Video: flv, yuv420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 44.92 tbc
    Stream #0.1(eng): Audio: adpcm_swf, 32000 Hz, stereo, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
[adpcm_swf @ 0xa4ef60]Sample rate must be 11025, 22050 or 44100
Error while opening codec for output stream #0.1 - maybe incorrect parameters such as bit_rate, rate, width or height

I have above error. I checked this page http://www.ffmpeg.org/ffmpeg-doc.html but I could not understand much. Can some one help to figure out what should I be doing to get this video to flv in this case? The OS is Ubuntu 10.04 64 bit server edition and aptitude install winff was what I had used to get ffmpeg or any thing else.

share|improve this question

1 Answer 1

Try to start FFmpeg with "-ar 44100" to correct audio rate, and if quality matters, with a "-sameq". like the line below.

ffmpeg -i stats_estimation.mp4 -sameq -ar 44100 out.flv
share|improve this answer
Ok and is there a way on command line so that I preserve the aspect ratio of video. –  Bond Nov 8 '10 at 7:48
Normally it should not change resolution or aspect ratio, unless you force ffmpeg to resize source. here is a full guide to see all parameters of ffmpeg. ffmpeg.org/ffmpeg-doc.html#SEC6 –  risyasin Nov 11 '10 at 20:32

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.