Re: Maintaining sound card at a specific frequency

[Takashi Iwai <tiwai@suse.de>]

At Tue, 18 Jan 2005 09:01:21 -0800,
Mark Knecht wrote:
> 
> On Tue, 18 Jan 2005 17:48:30 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> > At Tue, 18 Jan 2005 16:50:36 +0100 (CET),
> > Giuliano Pochini wrote:
> > >
> > >
> > > On 17-Jan-2005 Patrick Shirkey wrote:
> > >
> > > >> I guess I'm wondering if there isn't some .asoundrc magic that could
> > > >> be done in my Linux account on this machine that would tell all
> > > >> applications (other than Jack for now) to use some virtual device that
> > > >> handles all frequencies. If that virtual device was the default and
> > > >> the resampling (for Mozilla/games/whatever) was done in software and
> > > >> the sound cards frequency was never changed then I think things would
> > > >> work much better.
> > > >>
> > > >
> > > > I think you can use default as the device name in .asoundrc and it
> > > > will be used as the default device for all apps.
> > >
> > > IMHO we should think on a good solution for this problem. Some
> > > cards have many channels/voices but the sample rate is common
> > > for all of them. Currently the only clean way to manage it is
> > > a control that locks the sample rate at a given frequency, but
> > > it isn't a nice solution because it requires explicit user
> > > intervention. In the echoaudio driver I implemented a kludge
> > > that automatically locks the sample frequency in order to avoid
> > > unwanted rate changes.
> > 
> > You can add a control to lock the sample rate (e.g. ICE1712).
> > 
> > 
> > Takashi
> > 
> 
> That could be a good solution if it would also set the initial
> frequency of the card.

The system clock of HDSP can be set via control API.  So, it works
like:
	amixer cset iface=PCM,name="Sample Clock Source" "Internal 48.0 kHz"

If this works like you want, only the locking is missing...


Takashi


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