newbie dumb question about init time and latency

[Sum]

Hi there, after using the EQ APO with win 11 I must say it works wonderfully! but curious in the analysist panel I saw 0 latency and 13ms init time.

what does that affects in reality? I guess that latency is what makes the sound delay/laggy between say in a FPS game I press my mouse and the time need for the gun fire to actually come out from my speaker, while init time is the time windows initially need to apply the EQ into my device (As EQ apo is always on in background so I assume the init time would mean first load)? or it actually means the init time is the time delay between I hit any play button til the sound is actually played out?

[Peter Verbeek]

The latency of the biquad filters (peak, high shelf, etc.) is tiny. The latency of the Graphic EQ convolution filter is somewhat larger but still very small. Both latencies are so small that you can't notice them although having more than one (say 5 or 10) Graphic EQ could be noticeable?

Of course Equalizer APO (the audio changing engine equalizerapo.dll) needs to read the config.txt file and all others files included by include commands. This will take some milliseconds (init time of first load as you're calling it). This can be notice if having many commands. But once read the latency are those as described above.

An example of the fast processing: In my Peace equalizer app a user can select a Butterworth filter (not important what it is) for a slider. Such a filter could produce 50 biquad filters with no latency to speak of. My experience is such that even a 1000 biquad filters setup isn't really noticeable. That's one of the reasons the Peace equalizer uses biquad filters as default instead of Graphic EQ (which the Configuration Editor uses for an EQ).

[Sum]

I see, thanks for the explaination! I am using REW to auto generate some 40eq filters per channel into txt file and load those into the config .txt for geeky chase for in room comply on target curve full range (My room is tiny and listen very near field, full range correction sounded more right for me).

So in the analysist window showing Latency of 0.0ms and init time for L and R channel being 12.7ms and 13.4ms basically means upon loading windows, it will take 13.4ms to load all those values and apply to the dac. and then afterwards the latency is below 0.01 ms latency?

[Etienne Dechamps]

Yes. Although initialization is not done when "loading Windows". APOs are loaded when an audio device is first used by an application. It is then unloaded if no applications have used the audio device in the last 5 seconds (IIRC). In other words, the init time is basically how long the first audio application has to wait for its audio stream to initialize.

[Peter Verbeek]

Yep as you're using biquad filters generated by REW. For fun you could copy the filters and paste them 10 times over in the config.txt and see what the latency (after loading) is.

[Sum]

Thanks all, that really solved all my curiousity. I was asking coz beside a music lover I really am a gamer also, so when making use of the EQ APO makes me amazed how bad my room is, and then at the same time if in gaming I won't want the sound to go into 15ms of delay or so, so it seems I can just leave it always on and call it a day