Sidechain on VLC is Delayed

[ABoredBunny]

Operating System Info

Other

Other OS

Pop! OS 22.04, Fedora 40

OBS Studio Version

Other

OBS Studio Version (Other)

30.2.3, 30.2.2

OBS Studio Log URL

https://obsproject.com/logs/oRs9IULk06NSseIM

OBS Studio Crash Log URL

No response

Expected Behavior

The compressor set to sidechain should react at the same speed, as one applied on Desktop Audio.

Current Behavior

The sidechain happens like a second later making it unusable for it's purpose

Steps to Reproduce

1. Create VLC Video Source
2. Add music files to playlist
3. Add Compressor to VLC Video Source
4. Set Sidechain/Ducking Source to Mic/Aux
5. Setup the Compressor, as an example: 20:1 Ratio, -60 Thresh, 1 ms Attack, 500 Release
6. Record it when talking into the Mic the volume gets lowered way too late
   ...
   Optional: Use the same settings on Desktop audio, play audio through source of choice, pan both. It's very noticeable.

Anything else we should know?

I tested this on my PC running Pop!, a Modded PS4 running Fedora 40. And someone talked about it on Reddit 7 Months ago on a M3 Max "Sidechaining compression is very slow/laggy"

[kkartaltepe]

VLC sources are typically buffered ~1 second ahead. Unfortunately this is just how VLC works so unless there is a way to configure it in vlc, someone would need to rewrite significant portions of how buffered audio works in obs.

[ABoredBunny]

VLC sources are typically buffered ~1 second ahead. Unfortunately this is just how VLC works so unless there is a way to configure it in vlc, someone would need to rewrite significant portions of how buffered audio works in obs.

Thanks, with that info I can just work around it. I just use NDI output on the VLC media, mute VLC and then use an NDI source for output with the compressor applied.

Although this should probably get some native fix. It seems kind of counter-intuitive to have the filter applied during a buffer stage.

[NikolaiSchreier]

This also affects every mixer action like muting, adjusting levels etc.
I can understand that the audio is buffered, but the playback mixer actions like muting, adjusting audio level and indeed sidechain/ducking should be possible without latency (like the VLC player does itself).
I don't know the implementation details but it seems strange to me that the mixer is implemented on the buffer input side and not on the playback side.