dxs_support detection or feature broken?

dxs_support detection or feature broken?

[John Gotts]

I have an ASUS A7V8X motherboard with a VIA VT8233 audio controller equipped
with SPDIF.  I have a set of digital speakers and use the SPDIF out for
everything possible.  (The speakers will fall back to analog if there is no
digital signal present.)

00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233 AC97 Audio Controller (rev 50)

For a long time (through 1.0.0rc1) I had been using plug:spdif as my audio
device and aplay had no problems playing 22,050 Hz WAV files:

aplay -D plug:spdif <filename>.wav

But with 1.0.1 my speakers started playing 22,050 Hz WAV files at 48,000 Hz.

After reading the following thread:

http://www.mail-archive.com/alsa-devel@lists.sourceforge.net/msg10448.html

I added the following line to my /etc/modules.conf:

options snd-via82xx dxs_support=3

and plug:spdif is working again.  One message says "By default snd-via82xx uses
dxs_support=3 (except for certain known motherboards)."  Either my motherboard
should become unknown or this feature is not working correctly.

John

-- 
John GOTTS <jgotts@linuxsavvy.com>  http://linuxsavvy.com/staff/jgotts


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Re: dxs_support detection or feature broken?

[Takashi Iwai]

At Fri, 23 Jan 2004 23:40:18 -0500,
John Gotts wrote:
> 
> I have an ASUS A7V8X motherboard with a VIA VT8233 audio controller equipped
> with SPDIF.  I have a set of digital speakers and use the SPDIF out for
> everything possible.  (The speakers will fall back to analog if there is no
> digital signal present.)
> 
> 00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233 AC97 Audio Controller (rev 50)
> 
> For a long time (through 1.0.0rc1) I had been using plug:spdif as my audio
> device and aplay had no problems playing 22,050 Hz WAV files:
> 
> aplay -D plug:spdif <filename>.wav
> 
> But with 1.0.1 my speakers started playing 22,050 Hz WAV files at 48,000 Hz.
> 
> After reading the following thread:
> 
> http://www.mail-archive.com/alsa-devel@lists.sourceforge.net/msg10448.html
> 
> I added the following line to my /etc/modules.conf:
> 
> options snd-via82xx dxs_support=3
> 
> and plug:spdif is working again.  One message says "By default snd-via82xx uses
> dxs_support=3 (except for certain known motherboards)."  Either my motherboard
> should become unknown or this feature is not working correctly.

well, the dxs_support detection is correct.
the problem is that spdif doesn't support 22.5kHz but the via82xx
driver doesn't restrict the sample rates for spdif.
i guess 44.1khz sample can be played correctly even without "plug".

ok, this bug should be fixed in the future...

a workaround is to define your own pcm such as

pcm.myspdif {
	type plug
	slave {
		pcm "spdif"
		rate 48000
	}
}

and

	% apaly -Dmyspdif 22500hz.wav


Takashi


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Re: dxs_support detection or feature broken?

[jgotts]

In message <s5hr7xnufbz.wl@alsa2.suse.de>, Takashi Iwai writes:

>At Fri, 23 Jan 2004 23:40:18 -0500,
>John Gotts wrote:

>> I have an ASUS A7V8X motherboard with a VIA VT8233 audio controller equipped
>> with SPDIF.  I have a set of digital speakers and use the SPDIF out for
>> everything possible.  (The speakers will fall back to analog if there is no
>> digital signal present.)

>> 00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233 AC97 Audi
>o Controller (rev 50)

>> For a long time (through 1.0.0rc1) I had been using plug:spdif as my audio
>> device and aplay had no problems playing 22,050 Hz WAV files:

>> aplay -D plug:spdif <filename>.wav

>> But with 1.0.1 my speakers started playing 22,050 Hz WAV files at 48,000 Hz.

>> After reading the following thread:

>> http://www.mail-archive.com/alsa-devel@lists.sourceforge.net/msg10448.html

>> I added the following line to my /etc/modules.conf:

>> options snd-via82xx dxs_support=3

>> and plug:spdif is working again.  One message says "By default snd-via82xx u
>ses
>> dxs_support=3 (except for certain known motherboards)."  Either my motherboa
>rd
>> should become unknown or this feature is not working correctly.

>well, the dxs_support detection is correct.
>the problem is that spdif doesn't support 22.5kHz but the via82xx
>driver doesn't restrict the sample rates for spdif.
>i guess 44.1khz sample can be played correctly even without "plug".

>ok, this bug should be fixed in the future...

>a workaround is to define your own pcm such as

>pcm.myspdif {
>	type plug
>	slave {
>		pcm "spdif"
>		rate 48000
>	}
>}

>and

>	% apaly -Dmyspdif 22500hz.wav

Thanks for the workaround.  Believe it or not, I used it first, but I thought
disabling dxs_support was the better workaround.  Now that I know dxs_support
works I'll define pcm.fspdif (for functional SPDIF) in my /etc/asound.conf
until the bug is fixed.

By the way, congratulations on getting version 1 out the door.  I'm glad ALSA
is now a standard Linux component.  Your hard work has not gone unappreciated.

Thanks,
John

-- 
John GOTTS <jgotts@linuxsavvy.com>  http://linuxsavvy.com/staff/jgotts


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