Re: [ecasound] Problem with 2.7.0

[Kai V. <kve...@ec...>]

Hi,

On Mon, 19 Oct 2009, Pierre Lorenzon wrote:

>> hmm, ok, I have one hypothesis. Here's one snapshot, let me
>> know if it helps:
>
>  Yes it does ! The problem no longer exists with this version.

ok, great, that is really good news. I now wrote a longer mail about this 
to ALSA list:
http://permalink.gmane.org/gmane.linux.alsa.devel/67752

The good news is that this bug should not hit too many people. Most ALSA 
PCMs support power-of-two period-sizes (-b:1024, -b:128, ...), and in 
these cases no glitches should not occur.

In your specific case, I think the PCM doesn't support -b:1024 but 
something close, as the block/period size. Now due to the bug this results 
in discontinuity at every block, leading to glitches at a rate of ~20Hz 
when playing 44.1kHz audio. This matches pretty closely what you 
described.

>> Also, I'd be interested to know which version of alsa-lib
>  1.0.13
>> (libasound) do you have, and which kernel version?
>  2.6.22.5

These match as well. These still have the old implementation of 
snd_pcm_sw_params_set_xfer_align both in alsa-lib and in kernel.

Thanks for helping to track this down! I'll release 2.7.1 soonish with 
this fix (and possibly a few others as well) included.