Crackly sound with dmix rate 48000

Crackly sound with dmix rate 48000

[Daniel Drake]

Hi,

In our musical activities, the OLPC/Sugar platform uses csound which in
turn uses ALSA for playing sounds.

On our latest XO hardware model, where we now use HDA instead of cs5536,
we are experiencing some crackly sounds from our csound-based
applications. Other apps are fine.

We discovered that changing the dmix rate from 48000 to 44100 solves the
cracklyness.

What does this indicate?

Might csound be producing sounds at rate 44100, which dmix previously
had to convert to 48000, which was too taxing to the system?

Any suggestions for how to diagnose this further? (or would changing the
rate be seen as a reasonable thing to do in this situation?)

Thanks,
Daniel

Re: Crackly sound with dmix rate 48000

[Takashi Iwai]

At Mon, 09 Nov 2009 13:34:34 +0000,
Daniel Drake wrote:
> 
> Hi,
> 
> In our musical activities, the OLPC/Sugar platform uses csound which in
> turn uses ALSA for playing sounds.
> 
> On our latest XO hardware model, where we now use HDA instead of cs5536,
> we are experiencing some crackly sounds from our csound-based
> applications. Other apps are fine.
> 
> We discovered that changing the dmix rate from 48000 to 44100 solves the
> cracklyness.
> 
> What does this indicate?
> 
> Might csound be producing sounds at rate 44100, which dmix previously
> had to convert to 48000, which was too taxing to the system?

Might be.  Another possible problem is the position update bug.
Try to pass position_fix=1 option and/or bdl_pos_adj=0 to
snd-hda-intel module.


Takashi