When signed 32-bit audio arrived to pulseaudio-output and volume was
lowered, audio data was broken. In the function `process_volume`, the
type of the data is switched by `bytes_per_channel`. However the size of
signed 32-bit integer and the size of float are same so that the signed
32-bit integer is processed as float.
This commit changes these items.
- Use `format` instead of `bytes_per_channel` so that all the sample
types can be differentiated.
- Change `short` to `int16_t` and renames existing function
`process_short` to `process_s16` to clarify the function is
processing signed 16-bit.
0eed7ca98f