[pulseaudio-discuss] Virtual audio cable - high cpu usage

[Sean Greenslade]

On Sat, Jan 30, 2021 at 12:29:46PM +0100, Renaud GHIA wrote:
> Hi,
> 
> I use pulseaudio in a use case where the cpu usage is very high (30%) and
> IHMO this is not normal.
> I tried all the tricks to decrease the cpu load without success
> (resampling-method etc...). The cpu remains high.
> 
> My use case is simple. I redirect the sound output of an application to the
> sound input of another application (in this case ffmpeg). I load two
> modules to create my virtual audio cable like this:
> 
> pactl load-module module-null-sink sink_name=VAC_spk
> sink_properties=device.description=VAC
> 
> pactl load-module module-remap-source master=VAC_spk.monitor
> source_name=VAC1_mic source_properties=device.description=VAC
> 
> Everything works perfectly, except the cpu which is 30% for this simple use
> case.
> My cpu is a AMD threadripper and i'am with the latest stable release
> pulseaudio 14.2 freshly compiled,
> Do you know how to lower the CPU usage?

Have you made sure that everything in the chain is operating at the same
sample rate? That could be a cause of high CPU usage.

Also, I've seen high CPU usage on my setups when I have a large number
of pulse clients running and I open pavucontrol, since pavucontrol
creates a source output for every client in order to display its VU
meters.

If neither of those are the cause, can you share the output of the
command "pacmd list" when you're seeing high CPU usage? That might shed
additional light on what's happening in your setup.

--Sean