How to convert MP3 to AMR using ffmpeg in windows commandline

Question

Using windows based ffmpeg to convert MP3 to AMR. For some reason it fails with error as given below.

Don't know how to given the correct parameters for AMR.

C:\Program Files (x86)\AMR to MP3 Converter>ffmpeg -i mfile.mp3 -ar 8000 -ab 12.2k audio.amr
FFmpeg version SVN-r26400, Copyright (c) 2000-2011 the FFmpeg developers
  built on Jan 18 2011 04:07:05 with gcc 4.4.2
  configuration: --enable-gpl --enable-version3 --enable-libgsm --enable-libvorb
is --enable-libtheora --enable-libspeex --enable-libmp3lame --enable-libopenjpeg
 --enable-libschroedinger --enable-libopencore_amrwb --enable-libopencore_amrnb
--enable-libvpx --disable-decoder=libvpx --arch=x86 --enable-runtime-cpudetect -
-enable-libxvid --enable-libx264 --enable-librtmp --extra-libs='-lrtmp -lpolarss
l -lws2_32 -lwinmm' --target-os=mingw32 --enable-avisynth --enable-w32threads --
cross-prefix=i686-mingw32- --cc='ccache i686-mingw32-gcc' --enable-memalign-hack

  libavutil     50.36. 0 / 50.36. 0
  libavcore      0.16. 1 /  0.16. 1
  libavcodec    52.108. 0 / 52.108. 0
  libavformat   52.93. 0 / 52.93. 0
  libavdevice   52. 2. 3 / 52. 2. 3
  libavfilter    1.74. 0 /  1.74. 0
  libswscale     0.12. 0 /  0.12. 0
[mp3 @ 003abeb0] max_analyze_duration reached
[mp3 @ 003abeb0] Estimating duration from bitrate, this may be inaccurate
Input #0, mp3, from 'mfile.mp3':
  Metadata:
    title           : SPL_TRACK
    artist          : Krishnan
    album           : Lord
    genre           : Lord
    track           : 5
  Duration: 00:30:06.00, start: 0.000000, bitrate: 127 kb/s
    Stream #0.0: Audio: mp3, 44100 Hz, 2 channels, s16, 128 kb/s
[libopencore_amrnb @ 017e0d20] Only mono supported
Output #0, amr, to 'audio.amr':
    Stream #0.0: Audio: libopencore_amrnb, 8000 Hz, 2 channels, s16, 12 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
Error while opening encoder for output stream #0.0 - maybe incorrect parameters
such as bit_rate, rate, width or height

Answer 1

As the error msg says, Only mono supported , so add -ac 1 .

In any case, your ffmpeg is prehistoric. Get a new binary from https://ffmpeg.zeranoe.com/builds/