Re: [iPAQ] Audio driver questions

Nicolas Pitre wrote:
> On Fri, 1 Sep 2000, Carl Worth wrote:
>
> > Greetings to the iPAQ pack,
> >
> > I have been experimenting with the audio capabilities of the iPAQ
> > under Linux. Here are my observations so far:
> >
> > 1) The speaker is on all the time. If you put your ear close
> > to the speaker you can hear some light static. Isn't this
> > wasting power? Is this avoidable? Is there a way to turn
> > the speaker off?
>
> Yes, yes and yes. Simply not done right ATM. The DAC power could be
> shut off when there is no opened instance of the audio driver. However
> the UDA1341 settings would need to be remade once the device is opened
> i.e. the chip repowered to keep mixer settings consistency.

I'm playing with having the driver do something like that at the moment, at
least dealing with amplifier power (if not DAC). This is related to some
changes I'm making for OSS compliance reasons (certain changes should only take
effect at certain times.
In fact certain changes should probably only be sent over to the codec at the
start of playback and/or recording.

>
> > 2) Volume control does not seem to work. I tried the volume
> > slider in gqmpeg and it had no effect. Next, I downloaded
> > smixer, a small command-line mixer from:
> >
> > http://centerclick.org/programs/smixer/
> >
> > It compiles out-of-the box on skiffcluster and runs on the
> > iPAQ just fine. It will report a volume, (say 70%), allow
> > me to set the volume, (say to 25%), and then query the
> > mixer again, (and report 25%). So some number seems to be
> > getting stored somewhere, (a hardware register
> > hopefully). However, the actual volume I hear is not any
> > different.
>
> It works on Assabet, and shouldnt be different on iPaq. I didn't try
> Linux on my Ipaq yet (waiting for the flash issue to be resolved).

It works fine on two of my iPAQ's, but on a third I've noticed some strange
behavior similar to Carl Worth's, but it varies depending on what I play (ie. a
44.1KHz vs 22.05KHz). and from those behaviors and the mixer behaviors I'm
seeing on that unit, I'm starting to suspect that there may be something
different about the L3 bus on some iPAQ's. It might just be induced noise on
the bus, or something else on the L3 bus effecting it's behavior. Any ideas
from people at Compaq or elsewhere would be greatly appreciated.

Thanks,
Erik
Received on Tue Sep 5 14:22:20 2000