An audio file can be used to convert and read from. It uses libAV to convert
about any audio format to a one channel PCM stream of a chosen sample rate. There is
support for movie files as well, the first audio channel is then used as input.
The resource is either a local file or a type of stream supported by libAV (e.g. HTTP streams);
For a list of audio decoders the following command is practical:
avconv -decoders | grep -E "^A" | sort
A... 8svx_exp 8SVX exponential
A... 8svx_fib 8SVX fibonacci
A... aac AAC (Advanced Audio Coding)
A... aac_latm AAC LATM (Advanced Audio Coding LATM syntax)
...