Echo cancel not working

[darkbasic]

I recently upgraded to Fedora 34 and since it switched to pipewire I can't set up pulseaudio to do echo cancellation anymore.
I decided to try PulseEffects' WebRTC filter to achieve the same goal, but it doesn't work: there is no way to select which source should I use to echo cancel and if I reproduce some audio from my computer speakers I can clearly see in the PulseEffect Source filtered microphone output. Am I doing something wrong?

[wwmm]

there is no way to select which source should I use to echo cancel

Unfortunately that is right. The webrtc plugin by default uses the sound card monitors as source for echo cancellation.

I have to think carefully about what to do with this plugin in the future. The plugin currently used is a built-in GStreamer plugin. But in the gtk4 port I am using native PipeWire filters instead of GStreamer. I will have to write myself a new plugin for echo cancellation. I am not sure how yet...

[darkbasic]

The webrtc plugin by default uses the sound card monitors as source for echo cancellation

That would be good enough for my needs, but unfortunately it doesn't work at all. Any idea why?

[wwmm]

Kill the current instance pulseeffects -q and restart it in debug mode G_MESSAGES_DEBUG=pulseeffects pulseeffects. THis way we will see what is being done under the hoods.

At least for me this webrtc plugin has always been a little inconsistent when it comes to echo cancellation. Sometimes it is really good but sometimes it is almost like it is not there. It was one of the hardest plugins to integrate exactly because of the need of a secondary GStreamer pipeline for the probe recording the monitors.

[wwmm]

This should not be a problem in EasyEffects 6.0.0

[darkbasic]

Unfortunately it still doesn't work with EasyEffects 7.0.0 and pipewire 0.3.61: https://youtu.be/h1910Z7ALGE

[darkbasic]

@wwmm do you want to re-open this issue or would you rather prefer me to create a new one?

[wwmm]

do you want to re-open this issue or would you rather prefer me to create a new one?

We can reopen this one but it is not clear to me what you expect to achieve in the video if OBS is the only stream in the mic tab and effects are disabled for it. The only reason why there is signal passing through the echo canceller plugin is pavucontrol. It's level meter streams trigger a not intended behavior I think it should not be happening anymore.

[darkbasic]

it is not clear to me what you expect to achieve in the video if OBS is the only stream in the mic tab and effects are disabled for it

I'm sorry, I saw the signal going through and I didn't notice it was disabled.
It's not just because of pavucontrol, it's the same even without it as you can see: https://youtu.be/AO7ZLnl55js
Sometimes switching to another tab and then going back to input effects fixes it, sometimes not.

Anyway what I want to achieve is the following: OBS records from the microphone while supertuxkart is playing some background music, which should get echo cancelled and thus nothing gets recorded (except maybe some noise, but the noise reduction plugin works very well).
In order to achieve so I have to enable OBS in the inputs (which I did in the second video) and maybe (I have no idea how the echo cancel plugin selects its source) enable the supertuxkart output as well. As you can see from the second video the output of the echo canceller is the same as the input, even with OBS enabled.

P.S.
I've forgot to actually unmute the mic in OBS, but it's the exact same thing if you do so.

[wwmm]

It's not just because of pavucontrol, it's the same even without it as you can see: https://youtu.be/AO7ZLnl55js
Sometimes switching to another tab and then going back to input effects fixes it, sometimes not.

Run pw-dot. Its output file can be viewed with xdot and will show the links between filters and devices as well as the link state. I want to see what is linked to EasyEffects virtual source.

OBS records from the microphone while supertuxkart is playing some background music, which should get echo cancelled and thus nothing gets recorded

I am not sure the speex echo canceller will go as far as completely removing the background music recorded by the mic. The most I have seen it doing is removing some minor echo in some situations. What you desire may be beyond its capabilities.

I have no idea how the echo cancel plugin selects its source

Besides the connections to the filters that are before and after it in the effects pipeline the echo canceller needs to link a probe to the soundcard device. At this moment the probes are automatically linked to the output device currently being used by EasyEffects output effects pipeline. IT should be the same you selected in EasyEffects PipeWire's Device Management tab.

[darkbasic]

I want to see what is linked to EasyEffects virtual source.

pw.zip

Shouldn't helvum achieve the same goal?

https://youtu.be/3LjqKTWa80k

At this moment the probes are automatically linked to the output device currently being used by EasyEffects output effects pipeline

As you can see from the previous video according to helvum these probes are not attached at all, but manually attaching them doesn't do anything as well.

I am not sure the speex echo canceller will go as far as completely removing the background music recorded by the mic

Pulseaudio echo cancellation (backed by webrtc-audio-processing) is so good that you won't be able to tell if there is anything playing back in the background. On the contrary EasyEffects echo cancellation is so bad that it actually worsen things. I'm wondering if this is because the probes aren't attached correctly or because it doesn't compensate the clock drift between the two different input and output devices (the input is an USB webcam and the output is an USB soundbar).

[wwmm]

Shouldn't helvum achieve the same goal?

I think pw-dot output is cleaner. And it shows me the sate of each link.

As you can see from the previous video according to helvum these probes are not attached at all, but manually attaching them doesn't do anything as well.

It seems a regression was introduced at some point. I am doing some tests and I can see this happening on my computer now.

I'm wondering if this is because the probes aren't attached correctly or because it doesn't compensate the clock drift between the two different input and output devices

Not having the probes connected definitely do not help. But Pulseaudio is not using the speex library to do echo cancellation. If I remember well it uses a custom version of the webrtc library that seems to only exist in Pulseaudio sources. I have never seen it available as library for general purpose use.

[darkbasic]

I have never seen it available as library for general purpose use.

https://gitlab.freedesktop.org/pulseaudio/webrtc-audio-processing

I think that pulseaudio used to do clock drift compensation, but pipewire (which uses the same library) doesn't: https://gitlab.freedesktop.org/pipewire/pipewire/-/blob/master/spa/plugins/aec/aec-webrtc.cpp#L103

[wwmm]

I have updated our master branch fixing the regression about the probe not being linked. But I think that the other issues are just the speex library not being as good as webrtc. Or it needs to be hooked at the server side for it to actually be reliable...

I think that pulseaudio used to do clock drift compensation, but pipewire (which uses the same library) doesn't: >https://gitlab.freedesktop.org/pipewire/pipewire/-/blob/master/spa/plugins/aec/aec-webrtc.cpp#L103

I will try to find some time to take a look at it. The library itself seems to have no documentation at all. So looking at how people have been using it seems to be the only way...