Re: How do different sound cards dynamically use different configurations?

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Hi Sean,

On 2022/7/20 上午2:59, Sean Greenslade wrote:
On Mon, Jul 18, 2022 at 02:42:07PM +0800, zhaochengyi@xxxxxxxxxxxxx wrote:
On 2022/7/17 上午3:18, Sean Greenslade wrote:
On Fri, Jul 15, 2022 at 06:04:49PM +0800, zhaochengyi@xxxxxxxxxxxxx wrote:
Hi guys,

On a special PC, it is required to start the pulseaudio daemon
with some special parameters in the file /etc/pulse/daemon.conf,
as follows:

default-sample-rate = 48000
default-fragments = 2
default-fragment-size-msec = 20

When plugging in a USB headset with a separate sound card to this special
I found that there was a noise in the playback audio. After investigation,
the sound card of the USB headset needs to use the following default

default-sample-rate = 44100
default-fragments = 4
default-fragment-size-msec = 25

After my further investigation, I found that noise is only generated
when changing the sink-input volume (pa_context_set_sink_input_volume),
but not when changing the sink volume (pa_context_set_sink_volume_by_index).

Can you describe this noise more specifically? Does it go away with
larger fragment size / counts? Have you enabled or disabled tsched? Have
you run with Pulse debug logging enabled and looked for any hints there
(e.g. underruns)?

I found out I only modified the item default-sample-rate in the file '/etc/pulse/daemon.conf', and then it will occur the the noise when changed the sink input volume.

  default-sample-rate = 48000
; alternate-sample-rate = 48000

I think the merge_requests 120 can fix this noise issue:

Thanks a lot.

Best Regards,

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