Re: pulseaudio / alc1220 sound clicks interruptions etc

Hello! My 50 cents: a human ear cannot tell the difference between
44.1kHz/16bps and 192kHz/32bps, given all other factors are equal.
FreeBSD's kernel does rate / format conversion[1] to
dev.pcm.X.play.vchanrate / dev.pcm.X.play.vchanformat if
dev.pcm.X.play.vchanmode is fixed or tries to adapt hardware rate / format
to what you are trying to play if vchanmode is adaptive. Your hardware and
driver must support that sample rate and format, of course.

The driver module reports supported sample rates and formats by
implementing channel_getcaps method. You can check your driver to see if it
actually supports what you want to get.

[1] See /usr/src/sys/dev/sound/pcm/feeder_rate.c and
/usr/src/sys/dev/sound/pcm/feeder_format.c

вт, 3 июн. 2025 г. в 04:50, Tomek CEDRO <tomek@cedro.info>:

> Hello world :-)
>
> I just switched to Intel Ultra 9 285K platform with ASUS mainboard
> which has currently very popular Realtek ALC1220 HDA sound codec. In
> theory this codec supports 32-bit sound with 192kHz samplerate
> playback (and some lower params for recording).
>
> I am experiencing really annoying sound clicks and glitches /
> interruptions on FreeBSD that are hard to stand when using anything
> beyond 16-bit 44.1kHz sound. At 48kHz glitches are rare but already
> show up, at 96 and 192kHz sound is unusable. No problems like this on
> windoze.There is one USB audio card (KM-BT1) that allows me to connect
> over bluetooth headphones and it has the same issues.
>
> I played around with almost all systctl settings latency buffers
> vchans bitperfects uadio params etc. It did not happen on the old
> hardware. I am running Enlightenment wit PulseAudio backend. PCI-e
> nvidia GTX1060 GPU. 14.2-RELEASE AMD64.
>
> Most likely PulseAudio is to blame as it also does some conversions on
> the fly and may not catch up. Also played with most of the PA
> daemon.conf settings with no good results, also in tandem with pcm
> sysctl settings. When vchanmode is set to adaptive then PA
> reconfrigures audio device to 16/44.1. When vchanmode is fixed and
> both params of pcm and pa are the same glitches are unbearable and
> their intensity corelates with applications use (i.e. switching
> windows distrubs sound etc).
>
> Are there any limitations for 24/32-bit audio and samplerate over
> 44.1kHz o n FreeBSD?
>
> Are there any tunables that may help OSS / PulseAudio run smoother?
>
> Are these known issues of ALC1220 sound codec?
>
> Should I run PulseAudio as system service so it gets realtime / nice
> access? If so how to make it secure as there is no rc script for that?
>
> Any hints welcome :-)
> Tomek
>
> --
> CeDeROM, SQ7MHZ, http://www.tomek.cedro.info
>
>