2012-06-08 16:40:13

by Markus Trippelsdorf

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Subject: [Bisected] ALSA: snd-usb: New streaming logic causes distortions on Burr-Brown DAC

I hear distortions on my Burr-Brown USB DAC whenever the (software)
volume is set to some value lower than 100% in mpd. The lower the volume
the bigger are the resulting distortions.

I've bisected this to the two commits below:
(One wouldn't compile without the other)

commit d399ff9593e088d33fb38f5206c6427825892baa
Author: Daniel Mack <[email protected]>
Date: Thu Apr 12 13:51:13 2012 +0200

ALSA: snd-usb: remove old streaming logic

commit edcd3633e72a1590c4cf46befe5e6cd03b5aec3e
Author: Daniel Mack <[email protected]>
Date: Thu Apr 12 13:51:12 2012 +0200

ALSA: snd-usb: switch over to new endpoint streaming logic

--
Markus


2012-06-08 17:51:19

by Jamie Heilman

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Subject: Re: [Bisected] ALSA: snd-usb: New streaming logic causes distortions on Burr-Brown DAC

Markus Trippelsdorf wrote:
> I hear distortions on my Burr-Brown USB DAC whenever the (software)
> volume is set to some value lower than 100% in mpd. The lower the volume
> the bigger are the resulting distortions.

see patch: http://marc.info/?l=linux-kernel&m=133905533312625&w=2

You're probably getting distortion because mpd decided it would use
a stream format that's only 8bit.


--
Jamie Heilman http://audible.transient.net/~jamie/

2012-06-08 18:11:58

by Markus Trippelsdorf

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Subject: Re: [Bisected] ALSA: snd-usb: New streaming logic causes distortions on Burr-Brown DAC

On 2012.06.08 at 17:50 +0000, Jamie Heilman wrote:
> Markus Trippelsdorf wrote:
> > I hear distortions on my Burr-Brown USB DAC whenever the (software)
> > volume is set to some value lower than 100% in mpd. The lower the volume
> > the bigger are the resulting distortions.
>
> see patch: http://marc.info/?l=linux-kernel&m=133905533312625&w=2
>
> You're probably getting distortion because mpd decided it would use
> a stream format that's only 8bit.

Yes. The patch fixes the issue. Many thanks.

--
Markus

2012-06-09 07:05:13

by Takashi Iwai

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Subject: Re: [Bisected] ALSA: snd-usb: New streaming logic causes distortions on Burr-Brown DAC

At Fri, 8 Jun 2012 20:11:54 +0200,
Markus Trippelsdorf wrote:
>
> On 2012.06.08 at 17:50 +0000, Jamie Heilman wrote:
> > Markus Trippelsdorf wrote:
> > > I hear distortions on my Burr-Brown USB DAC whenever the (software)
> > > volume is set to some value lower than 100% in mpd. The lower the volume
> > > the bigger are the resulting distortions.
> >
> > see patch: http://marc.info/?l=linux-kernel&m=133905533312625&w=2
> >
> > You're probably getting distortion because mpd decided it would use
> > a stream format that's only 8bit.
>
> Yes. The patch fixes the issue. Many thanks.

The patch is already in sound git tree, but missed in rc2.
It should be in rc3.


thanks,

Takashi