LinuxQuestions.org - How to convert stereo flv video to mono?

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How to convert stereo flv video to mono?

So I've got an flv video with horrible stereo sound (sound is good, but the stereo is very bad), which I listen to with my headphones. I need to make it mono in GNU/Linux since I have no Windows. Or with any Web-service, I don't know... Please suggest any tool to do so.

Use ffmpeg:

Quote:

ffmpeg -i input.flv -vcodec copy -acodec aac -ab 64k -ac 1 output.avi

Or, you can just use MPlayer

Quote:

mplayer -af pan=1:0.7:0.7 input.flv

Thanks. And how do I do it with MP4 video file using ffmpeg?
Tried your command, the error is:

Code:

Seems stream 1 codec frame rate differs from container frame rate: 59.83 (29917/500) -> 29.92 (29917/1000)

Can you run 'ffmpeg -i' on the video and post the output.

Code:

FFmpeg version git-2611e52, Copyright (c) 2000-2011 the FFmpeg developers

  built on Feb  6 2011 10:00:04 with gcc 4.5.2 20110127 (prerelease)

  configuration: --prefix=/usr --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libfaac --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-version3 --enable-nonfree --enable-runtime-cpudetect --disable-debug

  libavutil    50. 36. 0 / 50. 36. 0

  libavcore    0. 16. 1 /  0. 16. 1

  libavcodec  52.108. 0 / 52.108. 0

  libavformat  52. 94. 0 / 52. 94. 0

  libavdevice  52.  2. 3 / 52.  2. 3

  libavfilter  1. 74. 0 /  1. 74. 0

  libswscale    0. 12. 0 /  0. 12. 0

  libpostproc  51.  2. 0 / 51.  2. 0



Seems stream 1 codec frame rate differs from container frame rate: 59.83 (29917/500) -> 29.92 (29917/1000)

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'I-changed-the-filename.mp4':

  Metadata:

    major_brand    : mp42

    minor_version  : 0

    compatible_brands: isomavc1mp42

    creation_time  : 2010-06-24 17:27:32

  Duration: 00:08:04.23, start: 0.000000, bitrate: 522 kb/s

    Stream #0.0(und): Audio: aac, 44100 Hz, stereo, s16, 122 kb/s

    Metadata:

      creation_time  : 2010-06-24 17:27:32

    Stream #0.1(und): Video: h264, yuv420p, 480x360 [PAR 1:1 DAR 4:3], 397 kb/s, 29.92 fps, 29.92 tbr, 29917 tbn, 59.83 tbc

    Metadata:

      creation_time  : 2010-06-24 17:27:32

At least one output file must be specified

What happens when you try to encode this file? The error message you gave shouldn't be fatal ...

Yeah something like:

Code:

ffmpeg -i input.mp4 -vcodec copy -acodec aac -ab 122k -ac 1 output.mp4

Code:

$ ffmpeg -i 1.mp4 -vcodec copy -acodec aac -ab 122k -ac 1 output.mp4

FFmpeg version git-2611e52, Copyright (c) 2000-2011 the FFmpeg developers

  built on Feb  6 2011 10:00:04 with gcc 4.5.2 20110127 (prerelease)

  configuration: --prefix=/usr --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libfaac --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-version3 --enable-nonfree --enable-runtime-cpudetect --disable-debug

  libavutil    50. 36. 0 / 50. 36. 0

  libavcore    0. 16. 1 /  0. 16. 1

  libavcodec  52.108. 0 / 52.108. 0

  libavformat  52. 94. 0 / 52. 94. 0

  libavdevice  52.  2. 3 / 52.  2. 3

  libavfilter  1. 74. 0 /  1. 74. 0

  libswscale    0. 12. 0 /  0. 12. 0

  libpostproc  51.  2. 0 / 51.  2. 0



Seems stream 1 codec frame rate differs from container frame rate: 59.83 (29917/500) -> 29.92 (29917/1000)

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mp4':

  Metadata:

    major_brand    : mp42

    minor_version  : 0

    compatible_brands: isomavc1mp42

    creation_time  : 2010-06-24 17:27:32

  Duration: 00:08:04.23, start: 0.000000, bitrate: 522 kb/s

    Stream #0.0(und): Audio: aac, 44100 Hz, stereo, s16, 122 kb/s

    Metadata:

      creation_time  : 2010-06-24 17:27:32

    Stream #0.1(und): Video: h264, yuv420p, 480x360 [PAR 1:1 DAR 4:3], 397 kb/s, 29.92 fps, 29.92 tbr, 29917 tbn, 59.83 tbc

    Metadata:

      creation_time  : 2010-06-24 17:27:32

encoder 'aac' is experimental and might produce bad results.

Add '-strict experimental' if you want to use it.

Or use the non experimental encoder 'libfaac'.

That's all I got with my MP4 file... Nothing happens, no encoding.