Thanks for your response.
I understand the problem of clock drift when we have several audio hardware devices (with different qwartz).
But here, it's a pity that the null video driver has an independent clock...
Concerning pipewire, for now it doesn't work with our particular application (no sound), but it seems to evolve quickly.
I haven't tried jack for now, but if it depends on pulseaudio, won't I have the same problem?
Renaud
Le jeu. 4 févr. 2021 à 00:20, Alexander E. Patrakov <patrakov@xxxxxxxxx> a écrit :
_______________________________________________чт, 4 февр. 2021 г. в 03:10, Renaud GHIA <rghia@xxxxxxxxx>:Thank you for the tip.Now I am sure that resampling does not apply (see below).But unfortunately pulseaudio always consumes 30% of one CPU core!The reason is that you are using module-loopback. Due to a potential difference between the clocks on the null sink and on the real sound card (even though both report 44100 Hz), it always has to resample in order to correct for the clock skew. If you don't understand, here is an analogy: you have two mechanical watches. Even though both claim that their hour hand makes one full circle every 12 hours, in fact, if left unattended, they will diverge over time. There is no way to avoid that, except by moving to Jack or PipeWire which simply don't introduce a null sink with an independent clock.If you decide to stay on PulseAudio, you can tweak the resampling method. The default, speex-float-1, is light on the CPU resources and should produce no distortions detectable by human ear on typical speech and music. It does produce easily detectable distortions on specifically crafted signals. If you want to make sure that the resampler is transparent no matter what is thrown at it, use speex-float-5. There is no point in going higher than that.--Alexander E. Patrakov
CV: http://u.pc.cd/wT8otalK
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