Re: [Openvortex-dev] New preview available.

[Manuel Jander]

Hello,

On Sat, 2003-09-20 at 23:22, J. Gordon Wolfe wrote: 
> Sure enough... I threw in a couple of calls to
> vortex_mix_setvolumebyte() and now it works as you described, switching
> over when I use the spdif device and everything.  Guess we ought to have
> a slider in the alsa mixer for this thing.  Interestingly (or perhaps
> not), audio played through the spdif device is much louder than audio
> played through the adb device and sent over the spdif.  I played a
> little with the parameter given to vortex_mix_setvolumebyte(), but I
> didn't find anything that gave me increased volume without gross
> distortion.

A Mixer output or input  gain of cero, is no gain nor atenuation. A gain
of 8 is a 6dB gain (measured as power). That yield a factor 2 voltage
gain, and would translate a 16bit amplitude signal into a 17bit
representation. I guess thats why the binary driver uses gain=8 for
Mixer input and Output, to fit the 16bit stream into 18bit full scale.
But strangely while this works well on the AU8820, its too much
amplification on a AU8830 generating distortion. The AU8810 should be
more similar to the AU8830 than the AU8820.
The output volume of the SPDIF depends pretty much on the SPDIF
receiver. In the digital realm, there just the same bits as that who go
into the AC97 codec.

> > > Now, as for the SPDIF device, once I take out that hwwrite line, it
> > > seems to work.  In fact I think the sound quality is better than when I
> > > took from the ADB device before.  However, when I play 44.1KHz ogg
> > > files, the playback is a little too fast... I have some 48KHz flac files
> > > which play correctly.  I tried changing the samplerate passed to
> > > vortex_spdif_init(), but there was no change.
> > > 
> > >  - Gordon
> > 
> > 44100Hz is still a mistery, since it uses some kind of external clock
> > (external to the AU88x0 chip).
> > 
> Argh, I would kill to be able to output my oggs directly through the
> spdif!  Well I guess I should be grateful... 2 weeks ago my spdif didn't
> do anything. :-)

Dont desperate. Many things have seme impossible, and finally we got
them working, so dont loose faith :D

> Wow, that was pretty thorough.  Well, I'm starting to get a better grip
> on whats going on... I don't know how you figured out all this
> initially, but good work!

Well there was a background lot of work from other people, and a hand
full of luck too.

Best Regards

Manuel Jander.