[FFmpeg-user] Unable to transcode from aac to amrwb.

[NITIN SAGAR]

Hi all,
I am a new bie here, trying to use a video source and transcode its aac
audio to amr directly.
command being used is:
ffmpeg -i input.mp4 -vn out.amr

root at ubuntu:~/ffmpeg# ffmpeg -i '/home/nitin/Downloads/Skyfall.mp4' -vn
-c:a amrwbencout.amr
ffmpeg version git-2012-10-29-19add32 Copyright (c) 2000-2012 the FFmpeg
developers
  built on Oct 29 2012 23:59:33 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --enable-gpl --enable-libx264 --enable-libmp3lame
--enable-nonfree
  libavutil      52.  1.100 / 52.  1.100
  libavcodec     54. 69.100 / 54. 69.100
  libavformat    54. 35.100 / 54. 35.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 20.108 /  3. 20.108
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 16.100 /  0. 16.100
  libpostproc    52.  1.100 / 52.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/nitin/Downloads/Skyfall.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2012-07-30 14:49:01
  Duration: 00:02:31.19, start: 0.000000, bitrate: 2770 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1920x1080, 2576 kb/s, 23.98 fps, 23.98 tbr, 48k tbn, 47.95 tbc
    Metadata:
      creation_time   : 1970-01-01 00:00:00
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo,
s16, 191 kb/s
    Metadata:
      creation_time   : 2012-07-30 14:49:01
      handler_name    : IsoMedia File Produced by Google, 5-11-2011
At least one output file must be specified
root at ubuntu:~/ffmpeg# ffmpeg -i '/home/nitin/Downloads/Skyfall.mp4' -vn
out.amrffmpeg version git-2012-10-29-19add32 Copyright (c) 2000-2012 the
FFmpeg developers
  built on Oct 29 2012 23:59:33 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --enable-gpl --enable-libx264 --enable-libmp3lame
--enable-nonfree
  libavutil      52.  1.100 / 52.  1.100
  libavcodec     54. 69.100 / 54. 69.100
  libavformat    54. 35.100 / 54. 35.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 20.108 /  3. 20.108
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 16.100 /  0. 16.100
  libpostproc    52.  1.100 / 52.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/nitin/Downloads/Skyfall.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2012-07-30 14:49:01
  Duration: 00:02:31.19, start: 0.000000, bitrate: 2770 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1920x1080, 2576 kb/s, 23.98 fps, 23.98 tbr, 48k tbn, 47.95 tbc
    Metadata:
      creation_time   : 1970-01-01 00:00:00
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo,
s16, 191 kb/s
    Metadata:
      creation_time   : 2012-07-30 14:49:01
      handler_name    : IsoMedia File Produced by Google, 5-11-2011
Output #0, amr, to 'out.amr':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    Stream #0:0(und): Audio: none, 0 channels, 128 kb/s
    Metadata:
      creation_time   : 2012-07-30 14:49:01
      handler_name    : IsoMedia File Produced by Google, 5-11-2011
Stream mapping:
  Stream #0:1 -> #0:0 (aac -> ?)
Encoder (codec none) not found for output stream #0:0

This is the error, if someone could pleas help me, would be of great help
to me...

Thanks in Advance
Nitin