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

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

[Markus Trippelsdorf]

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 <zonque@gmail.com>
Date:   Thu Apr 12 13:51:13 2012 +0200

    ALSA: snd-usb: remove old streaming logic

commit edcd3633e72a1590c4cf46befe5e6cd03b5aec3e
Author: Daniel Mack <zonque@gmail.com>
Date:   Thu Apr 12 13:51:12 2012 +0200

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

-- 
Markus

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

[Jamie Heilman]

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/

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

[Markus Trippelsdorf]

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

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

[Takashi Iwai]

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