Format /dev/dsp expects?

[Michael Schwendt]

On Mon, 25 Aug 2008 15:27:11 -0500, Mike McCarty wrote:

> Michael Schwendt wrote:
> > On Mon, 25 Aug 2008 14:26:25 -0500, Mike McCarty wrote:
> > 
> >> Can anyone tell me what formats /dev/dsp, /dev/dsp56k,
> >> /dev/audio, etc. expect? It seems that I can copy
> >> a WAV format file directly to /dev/dsp and get recognizable
> >> sound. I wonder just what format they actually expect.
> > 
> > /dev/audio used to accept µ-law encoding, /dev/dsp accepts raw pcm as
> > configured via ioctl. The device doesn't evaluate any WAV header.
> 
> Thanks! So, if I want to use sox, I can specify the output to be
> /dev/dsp and raw, and the input format to be whatever corresponds.

Ask kernel devs whether you can still expect a specific raw format.

There are several parameters that must match: bits per sample,
signed/unsigned samples, number of channels (mono/stereo), frequency

Btw, it's likely that /dev/dsp will go away in the future, as it's
only a compatibility device file for the old OSS driver architecture
(unload a kernel module, and the device file is gone). ALSA uses
different device files.