Audio on cx18 based cards (Hauppauge HVR1600)

Audio on cx18 based cards (Hauppauge HVR1600)

[Simon Farnsworth]

Hello,

I'm trying to make a Hauppauge HVR1600 (using the cx18 driver) work well
with Xine; Hans de Goede has sorted out the video side of the card for
me, and I now need to get the audio side cleared up.

I'm used to cards like the Hauppauge HVR1110, which exports an ALSA
interface for audio capture; the HVR1600 doesn't do this. Instead, it
exports a "video" device, /dev/video24 that appears to have some
variation on PCM audio on it instead of video.

How should I handle this in Xine's input_v4l.c? Should the driver be
changed to use ALSA? If not, how do I detect this case, and how should I
configure the PCM audio device?

If the driver needs modifying, I can do this, but I'll need an
explanation of how to do so without breaking things for other people -
I've not done much with ALSA drivers or with V4L2 drivers.
-- 
Simon Farnsworth

Re: Audio on cx18 based cards (Hauppauge HVR1600)

[Andy Walls]

On Thu, 2009-09-03 at 12:14 +0100, Simon Farnsworth wrote:
> Hello,
> 
> I'm trying to make a Hauppauge HVR1600 (using the cx18 driver) work well
> with Xine; Hans de Goede has sorted out the video side of the card for
> me, and I now need to get the audio side cleared up.
> 
> I'm used to cards like the Hauppauge HVR1110, which exports an ALSA
> interface for audio capture; the HVR1600 doesn't do this. Instead, it
> exports a "video" device, /dev/video24 that appears to have some
> variation on PCM audio on it instead of video.

Yes, it's PCM straight from the capture unit in the CX23418.



> How should I handle this in Xine's input_v4l.c? Should the driver be
> changed to use ALSA?

It would be nice to have.  Your the first person to really need it.  The
end result can be ported to ivtv too.


>  If not, how do I detect this case, and how should I
> configure the PCM audio device?

It can be configured with the V4L2 control ioctl()s.  It should the be a
case of making select() and read() calls.


> If the driver needs modifying, I can do this, but I'll need an
> explanation of how to do so without breaking things for other people -
> I've not done much with ALSA drivers or with V4L2 drivers.

The skeleton of cx18-alsa support is almost done, but the heavy lifting
is not.

http://linuxtv.org/hg/~awalls/mc-lab

I'll push any uncommitted changes I have lying around to that repo
tonight.


Regards,
Andy