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

[Takashi Iwai <tiwai@suse.de>]

At Fri, 06 Feb 2004 14:14:22 +0100,
Thomas Charbonnel wrote:
> 
> >>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.
> >
> 
> Ok, but it seems this can't be done with iecset,

hmm?  iecset will read/change "IEC958 Playback Default" (searching
both MIXER and PCM interfaces).
it doesn't change "IEC958 Playback PCM Stream", though.

>  so I'm back with my 
> question concerning amixer : all the 'value' fields of IEC ctls show a 
> question mark. Is this a problem with the driver ? If not what would be 
> the syntax to access those ctls ?

amixer doesn't handle IEC958 status properly.


> >>>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...
> >
> 
> In case you plan to implement those additions, let me know if there is 
> anything to adapt on the driver side.

sure.

anyway, we'll need to discuss the best way for this problem.
i'd like to avoid addition as much as possible.


Takashi


-------------------------------------------------------
The SF.Net email is sponsored by EclipseCon 2004
Premiere Conference on Open Tools Development and Integration
See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
http://www.eclipsecon.org/osdn