Hey Guys, I have a compressor that works by having an envelope follower (full rectifier with attack and release settings) following the uncompressed input, then applying the compression ratio to my input where the envelope follower samples are above the threshold (working in db for that part).
I am trying to get ARC working and have 2 thoughts how it might work, but it's difficult to find info online about the internals of any ARC techniques. Do either of these sound like reasonable approaches? #1 - watch the envelope follower, and if it's been spending too much time releasing to get back to normal, decrease the release time. Else, if it hasn't been spending enough time releasing and it often quickly hits the input, increase the release time. What I mean from an implementation standpoint is something like keep track of what % of the time over the last X milliseconds (100ms perhaps? I don't know...) that it's been releasing and use that to drive the release time up or down. A few numbers need tuning though which makes me feel like maybe this is not the correct answer since ARC seems to "just work" without parameters. #2 - watch the input data within a time window (again, say the last 100ms perhaps?) and see if the heights of the peaks and the depths of the valleys are pretty much consistent or if they are wildly all over the place. If they are pretty consistent, the compressor should use a longer release time, but if they are very different from each other, i should use a faster release time. What do you guys think / have i missed another, better way to do it? Thanks! PS I've also read that some ARC techniques may look at the (loudest?) frequency of the audio data and use that as the basis for the release times. Is that true? Is there a magic formula for calculating a release time from frequency? :P (im thinking they must use a windowed FFT to get the frequency...) -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
