[music-dsp] Musical signal AGC (compressor..normalizer)

Alex Raider flashinc at mail.ru
Wed Jan 14 15:21:42 EST 2004


>> I tried to program Automatic Gain Control
>> Can anyone suggest me better technique than I used?

RB> Hi Alex:
RB> http://www.tml.hut.fi/~pjhamala/dafx2002/dafx_hamalainen.pdf
RB> That's for a lookahead limiter.

Thanx for a link.

Really he does src signal  Z   delay line, not lookahead.
The paper is very basic, I myself to hit upon an ideas described in
this paper, because if one is patient enough to closely examine
matlab`s plots, he come to a conclusion
that envelope is slightly lags (phase shift)
and attack/delays behaviour should be improved in adaptive manner.. ;-)
I not a person who don`t realise such techniques, I am person who like
a details :-)

RB> But if you want to level whole tracks perhaps you should do a global RMS
RB> scan on each file and normalize each track according to average level rather
RB> than using a time-varying algorithm.

CoolEdit does same thing.

RB> Best wishes
RB> Ross.

Seems for me, that dumb RMS for 50 ms look-ahead buffer without
filter does better work than any combination of power estimator +
filter(smoother), because RMS is already does mean/averaging along look-ahead area.
I would test it using running summ RMS.

State of the Art!
 Flash inc. Alex Raider

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