[Jack-Devel] How do I eliminate pops between alsa_in and alsa loopback?

[crocket]

I realized that alsa loopback is not a reliable source for alsa_in. I
decided to substitute a real hardware audio device to my computer for alsa
loopback.

On Thu, Aug 1, 2019 at 8:35 PM crocket <crockabiscuit at gmail.com> wrote:

> I made ALSA applications output audio to jack by applying instructions on
> https://alsa.opensrc.org/Jack_and_Loopback_device_as_Alsa-to-Jack_bridge
>
> # Gentoo Linux aarch64 on Raspberry Pi 3 B+
>
> jackd -P 90 -d alsa -d speakers -p 512 -n 3 -P -r 48000
> jack_netsource -H 192.168.30.2 -o 0 -i 2 -O 0 -I 0 -n 3 -N guardian
>
> # Gentoo Linux amd64 on my desktop computer
>
> jackd -P 90 -d netone -p 512 -n 3 -r 48000
> alsa_out -j headphones -d headphones -c 2 -p 512 -n 3 -q 3
> alsa_in -j cloop -d cloop -c 2 -p 1024 -n 2 -q 3
>
> jackd, jack_netsource, alsa_in, and alsa_out belong to audio cgroup which
> allocates 95% of CPU time to its group members.
>
> While youtube videos are played in vivaldi web browser, chrome web
> browser, and firefox web browser, I occasionally hear audible pops. It
> seems all pops come from `alsa_in`. I also tried alsa_in -p 1024 -n 3 -q
> 2|3|4, but it doesn't eliminate pops.
>
> Here's a part of ~/.asoundrc on my desktop computer.
>
> pcm.loophw00 {
>   type hw
>   card Loopback
>   device 0
>   subdevice 0
>   format S16_LE
>   rate 48000
>   channels 2
> }
>
> pcm.lmix {
>   type dmix
>   ipc_key 219347
>   slave {
>     pcm "loophw00"
>     period_time 0
>     period_size 512
>     periods 4
>     format S16_LE
>     rate 48000
>     channels 2
>   }
>   bindings {
>     0 0
>     1 1
>   }
> }
>
> pcm.cloop {
>   type hw
>   card Loopback
>   device 1
>   subdevice 0
>   format S16_LE
>   rate 48000
>   channels 2
> }
>
> pcm.!default {
>   type plug
>   slave {
>     pcm "lmix"
>     format S16_LE
>     channels 2
>     rate 48000
>   }
>   rate_converter "samplerate_best"
> }
>
> Is it impossible to eliminate pops from alsa_in running on cloop which is
> just alsa loopback?
>
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