AGC in a compressor.

[lalalandsynth]

How does one implement AGC in a compressor , and one without it following the levels and jump up and down , rather something that just compensates for reduction , like in a lot of VST compressors today ?

[tulamide]

I thought about this as well over the years. The DSP pros will probably correct me, but for me those compressors are actually doing some kind of normalizing, which only makes sense with a certain window length (and therefore latency). So, instead of working per sample, you analyze a buffer and normalize it accordingly. If you keep the last buffer's "normalizing information" and use it in subsequent calculations, it should be fairly stable.

buffer one - normalized 17%
buffer two - would be 34%, mean with last buffer = 25.5%
buffer three - would be 5%, mean with last buffer would be 15.25%, which exceeds digital 0 dB, so 5% is taken
buffer four - would be 15%, mean with last buffer = 10%
etc.

[Spogg]

There was a topic some time ago that might interest you, with some examples and "discussions":

viewtopic.php?f=2&t=3448&hilit=agc

Cheers

Spogg

[lalalandsynth]

Thanks guys , will have a look.