Re: Alsa handling of spdif bits (was Re: Questions to HDSP users)

[Takashi Iwai <tiwai@suse.de>]

At Fri, 06 Feb 2004 12:22:08 +0100,
Thomas Charbonnel wrote:
> 
> (BTW Takashi iecset -h says 'audio on' is non-audio and 'audio off' is 
> audio but it seems to be the other way round, unless the hdsp driver is 
> wrong here...)

yep, fixed now on CVS :)

> The problem I see and I dislike with this is that iec bits are 
> associated with playback. This is probably fine with most devices, but 
> not with hardware that can do hardware routing, where you may want to 
> route signal through the S/PDIF out with a certain bit combination - no 
> playback is involved here. I believe a generic iec bits handling 
> interface is a good thing, but is should not be affected by the card's 
> status. Any comment on this Takashi ?

well, in that case, the put callback of "IEC958 Playback Default"
should change the corresponding register value immediately, too.


> > An aside: this is also complicated because to open the device, the
> > channels item in the slave.pcm section must match the iobox in
> > use (multiface or digiface) which have differing channel counts.
> > So when we do get this working, it will be a problem to handle
> > both cases in a conf file.
> > 
> 
> Not to mention that there is also a shift in the S/PDIF channels
> position when the card changes speed mode...
> Can the current configuration mechanism handle this properly ?

when the channel position changes dynamically according to the certain
state, it'd be difficult with the current config without addition...

> Similarly we would need different .conf files for the different hdsp
> cards, but seeing Takashi's patch, it seems .conf files are associated
> with a card using the generic driver name (here 'H-DSP'). Is there a way
> to affect a .conf file to a specific submodel ?

the easiest way is to change the driver name per model.
for example, emu10k1 driver provides "EMU10k1", "Audigy" and
"Audigy2" according to the model.


Takashi


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