Re: SPDIF/IEC958 sample rate on HDA/ALC882

[Takashi Iwai <tiwai@suse.de>]

At Tue, 28 Nov 2006 14:13:25 +0100,
Erik Slagter wrote:
> 
> Takashi Iwai wrote:
> >> iecset allows me to set the rate to 32/44.1/48 kHz, the spdif output is
> >> still at 48 kHz. Some other flags from iecset are actually honoured
> >> (like "data" and "emphasis").
> 
> > It's simply because iecset program doesn't support the rates over
> > 48kHz.  But the hda-intel driver supports the rate, AFAIK.
> > (At least, there is no particular code that restricts over-48kHz.)
> 
> The problem is that whatever I set the sampling rate to, the output is
> ALWAYS 48 Khz, either set to 32, 41 or 48 Khz. I am not even talking
> about the higher rates.
> 
> > One thing to be noted is that if you use "hw" PCM device, you have to
> > set up the SPDIF status bits _manually_ via control API.  If you use
> > "iec958" or "spdif" PCM device, you can pass these bits as optional
> > arguments at opening the PCM.
> 
> I've tried that, but it's ehhhrrrmmm lacking some documentation.

You have all the source code, what else? :)

> >> I can ask aplay to play at various rates (from a suitable PCM file), but
> >> it complains at any other rate than 44.1 or 48 (notably 32) kHz that the
> >> rate is not supported. It plays at 44.1 kHz though. And again converts
> >> it to 48 kHz! Sigh...
> 
> > Who complains?  At least, the driver won't.
> 
> aplay complains, I suspect as a result of a return value from the
> driver. I can give you the output if it helps. I can even do an strace.

strace doesn't help much, I guess.  Provide rather what exactly you
did and what exactly you got, at first.  I can't reproduce nor check
anything unless I get precise information.  Also, try always the
latest version if you want to debug/analyzie something, i.e. ALSA HG
version.

> >> Maybe I am using the wrong "hw", there is also a "hw:0,2" device, which
> >> I cannot make work properly at all (only one channel is output, large
> >> chunks are discarded, much much clipping).
> 
> > The first PCM device is for the multi-output PCM.  It's for both
> > analog and digital.  The dedicated SPDIF is the secondary one.
> 
> But why does the second interface gives _some_ (although wrong) output
> on my spdif output then?

No idea, possibly wrong parameters are passed.

> Anyway, I double checked and the alc882 CAN output at various rates,
> also on the sp/dif output.

It's likely true.  Better to check the proc file content of codec#*
file rather than reading datasheets (what are often wrong), though.


Takashi

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