Re: kern/52175: audio sometimes stutters

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Apr 18, 2017 at 07:40:00AM +0000, martin%NetBSD.org@localhost wrote:
> Most audio fallout has been resolved, but I still see this issue on one machine.
> 
> It happens randomly, even when the machine is otherwise mostly idle.
> Sometimes playback with:
> 
> 	mpg123 -o oss -q -r 48000 -b 8192
> 
> goes into "stutter" mode. This is the only audio user in my system, no mixing
> involved. When in that mode, I can pause the player, wait for audio to drain,
> continue the player and it will continue stuttering.
> 
> When I kill the player and restart it, everything is fine (usually).
> This effect happens (no hard statistics) on like 5% of the play backs.

I'm also hearing problems on a allwinner A20 (920Mhz ARM cortex-A7),
which seems related to ossaudio. When playing a file with mplayer
(which, I believe, uses ossaudio), there is stops and clicks
in the output. Playing the same file with audioplay is as perfect
as it can be. The file is:
RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 44100 Hz

Also, playing a sound from opencpn (which uses portaudio2, which uses
ossaudio). It hangs. ktrace shows what looks like an endless loop writing
the same 64k data block again and again (the file itself is less than 128KB,
but larger files shows the same behavior), at a very low rate.
I don't hear anything on output but maybe that's because the file
is played at a very low rate.

All this is with a netbsd-7 userland, but with an updated libossaudio.

Any idea what I could look at ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--