Re: [Openvortex-dev] New preview available.

[J. Gordon Wolfe]

On Sat, 2003-09-20 at 19:59, Manuel Jander wrote:
> Hello,
> 
> I apologise but you are completely wrong :) The mixspdif array is an
> array of mixer outputs which are used to collect all signals that should
> go into the SPDIF. If the "spdif" alsa device is used, this mixer output
> route to the SPDIFOUT is disconnected, and a direct route from the DMA
> engine to the SPDIFOUT is made.
> 
Heh, right after I sent my last mail I thought "hey, that probably
wasn't right"... oh well, clearly I still don't completely understand
this driver.

> I guess that you got silence because i forget to set the input and
> output volume of the mixer elements which connect the "adb" dma channel
> with the SPDIF out.
> 
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.

> > 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. :-)

> 
> I attached some diagrams (hope you dont get angry of this email size).
> They show the normal "adb" ALSA device in action, which routes are
> deleted/created when using the "spdif" ALSA device. 
> Well the attachment was to big, so i put them on:
> http://galadriel.mat.utfsm.cl/~mjander/aureal/techdoc/routes.png
> http://galadriel.mat.utfsm.cl/~mjander/aureal/techdoc/spdif.png
> 
> 
> Something that should be considered to avoid confusions:
> 
> - The Routing buses are the numbers indicated on the lines (routes).
> - Route details of SRC input/output arent shown. The diagrams only show
> the entire SRC block with its input and its output. On the contrary, the
> mixer is split into its input and output "blocks".
> - There are upto 32 ADB DMA channels, and they can be routed anywhere.
> - There are upto 32 mixer inputs, and they can be connected to any of
> the 16 mixer outputs.
> - There are upto 16 SampleRateConverter, and they can be connected from
> anywhere to anywhere, BUT care has to be taken, which sample rate is
> operating at its input or output, since there can not be different
> samplerates on a same ADB routing bus. Thats why exclusive routing buses
> are used when connecting the DMA to SRC's, and a single routing bus can
> be used for connecting the AC97 codec, which operates at fixed 48KHz.
> - Signals can only be split or mixed using the mixer. When routing and
> output to 2 different inputs, time division demultiplexing takes place
> (frame 1 goes into input 0, frame 2 into input 1, frame 3 into input 0,
> and so on). Same applies to routing 2 outputs into one input, but the
> routing in this case has to be handled by a special funcion (LRT).
> 
> Best Regards
> 
> Manuel Jander

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!

 - Gordon

-- 
J. Gordon Wolfe <address@hidden>