Converting Audio for Use as Mitel Hold Music

The music file has to be A-law or U-law or G.711 at 8 khz, 8 Bits, Mono. To do this you can either use sox or ffmpeg. To use sox:

sox -V input_file.wav -A -c 1 -r 8k -1 output.wav

Update: Seems some of these options are depreciated, if you run sox with the previous options you get:

sox WARN sox: Option `-A' is deprecated, use `-e a-law' instead.
sox WARN sox: Option `-1' is deprecated, use `-b 8' instead.

So as it says use:

sox -V input.mp3 -e a-law -c 1 -r 8k -b 8 output.wav

You can test this by using:

play output.wav

Or by using ffmpeg:

ffmpeg -i input_file.wav -acodec pcm_alaw -ar 8000 -ab 8k -sample_fmt s8 -ac 1 output.wav

This will show you infomation on the resulting file:

ffprobe -show_streams output.wav
Written on May 23, 2011