krishnagandhi@ubuntu:~/ffmpeg_sources$ ffmpeg -i input.mp4 output.wav
ffmpeg version 2.5.git Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --prefix=/home/krishnagandhi/ffmpeg_build --extra-cflags=-I/home/krishnagandhi/ffmpeg_build/include --extra-ldflags=-L/home/krishnagandhi/ffmpeg_build/lib --bindir=/home/krishnagandhi/bin --enable-gpl --enable-libx264
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
[als @ 0x336bda0] Floating point decoding is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x336b0e0] Failed to open codec in av_find_stream_info
[als @ 0x336bda0] Floating point decoding is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    creation_time   : 2009-02-05 14:46:31
  Duration: 00:00:14.98, start: 0.000000, bitrate: 4872 kb/s
    Stream #0:0(und): Audio: mp4als (mp4a / 0x6134706D), 192000 Hz, 2 channels, 4872 kb/s (default)
    Metadata:
      creation_time   : 2009-02-05 14:46:31
File 'output.wav' already exists. Overwrite ? [y/N] y
[abuffer @ 0x336afe0] Unable to parse option value "(null)" as sample format
    Last message repeated 1 times
[abuffer @ 0x336afe0] Error setting option sample_fmt to value (null).
[graph 0 input from stream 0:0 @ 0x3356840] Error applying options to the filter.
Error opening filters!
krishnagandhi@ubuntu:~/ffmpeg_sources$ ffmpeg -i input.mp4 output.wav