RE: [Linphone-users] help: pda without soundcard

[Jamey Hicks]

On Wed, 2003-12-10 at 00:06, Mike wrote:
> Jamey,
> 
> Thanks for your response.
> 
> I have a mips PDA running with uclinux os, and a DA/AD chip
> inside the PDA, but my uclinux kernel does not have the DSP 
> (/dev/dsp) driver. 
> 
> I have a non-standard DA/AD codes to play and record sound 
> already. I need a drivers for this hardware DA/AD chip.
> But I am still confued how many drivers are needed?
> There are DSP (/dev/dsp), OSS, and ALSA drivers.

/dev/dsp is actually the name for the OSS driver.  ALSA provides an OSS
emulator driver so you can have /dev/dsp for ALSA.  You do not need a
DSP chip to use either OSS or ALSA.

The OSS drivers are deprecated in Linux 2.6, so if you are going to
write a sound driver you should write an ALSA driver.  It is not that
difficult to start with an existing ALSA driver and produce one for your
hardware.

> DO I still need the DSP driver on top of the OSS or
> ALSA driver? 
> 
> Can OSS (or ALSA) driver work without DSP driver?
> 
> Which driver is better for the linphoneC ?

Even in the 2.4.x kernel, ALSA drivers give you better control over
buffering so that you can reduce the latency and get better interactive
response from linphone and linphonec.

> I am also wondering whether there is an small changes to
> make the sound working without the DSP, OSS or ALSA drivers.

You could by adding a new soundcard support in linphone/mediastreamer/,
but for about the same amount of work you can make an ALSA driver that
can be used by any program that you run on your PDA.

> Is ther any free DSP, OSS, or ALSA drivers available?

I think all of the OSS and ALSA drivers are free. See
http://www.alsa-project.org/

-Jamey