[music-dsp] Loudness Maximizer
richbreen at earthlink.net
Tue Jun 20 11:51:38 EDT 2000
Christofer - Many commercial CDs are clipped, many others are not, and clipping is not the only way
to get level. If a CD has been mastered with a WAVES L1, L2, or the Weiss limiters for example, it
will *not* be clipped. In addition, the fairly popular Apogee 'soft clip' feature clips without
creating completely square waveforms. Some mastering engineers however, still feel it's ok to go
for level by clipping (not good practice in my book, but unfortunately a reflection of the 'louder
at all costs' mind-set prevalent at the A&R level of the labels), though at least they're generally
careful about checking it to be sure there's nothing obviously audible. I think the tilt you
describe on the clipped waveform has little to do with any deliberate post-processing, but is rather
an idiosyncrasy of the particular mastering chain - For example, I recently had a CD mastered by one
of the mastering 'legends' here in LA who uses a custom designed all tube chain, with the final
stage being a pair of highly modified LA2As for limiting - examination of the final product reveals
a tilted clip like you describe in a number of places - probably just the result of DC blocking caps
somewhere in the signal path.
Hope that's helpful,
richbreen at earthlink.net
>From: "Christofer Bustad" <tosse.bustad at mailbox.swipnet.se>
>To: <music-dsp at shoko.calarts.edu>
>Subject: Re: [music-dsp] Loudness Maximizer
>Date: Mon, Jun 19, 2000, 2:02 PM
>Hi Thomas and thank you very much for your help!
>I looked at some recordings from a popular music CD, and the waveform
>looked like it had been clipped. The only thing that I couldn't understand
>was that the flat tops, that are created when a waveform is clipped, wasn't
>flat. They all tilted forward a little bit (to the right). Is this caused
>by some kind of filtering after the clipping? Or is the clipping that is
>used more advanced than just standard clipping (If (Input > Threshold)
>Output = Threshold; Else Output = Input)?
>If anyone knows anything more about this, I would appreciate some more info very much!
>Thanks in advance!
>----- Ursprungligt meddelande -----
>Från: Thomas Serafini <mister-t at lycosmail.com>
>Till: <music-dsp at shoko.calarts.edu>
>Skickat: den 19 juni 2000 13:30
>Ämne: Re: [music-dsp] Loudness Maximizer
>> Clipping is one of the most important key to maximize the loudness. I
>> suggest to use a combination of compression/limiting (with very fast attack
>> time) and clipping; there is no optimal balance between limiting and
>> clipping, so it is best if the user can adjust this value. This is how the
>> limiter of T-RackS (IK Multimedia) works.
>> Generaly look-ahead limiting has many side effects: for example it tends to
>> smooth fast transients, gaining loudness but loosing punch.
>> ----- Original Message -----
>> From: Christofer Bustad <tosse.bustad at mailbox.swipnet.se>
>> To: <music-dsp at shoko.calarts.edu>
>> Sent: Sunday, June 18, 2000 7:42 PM
>> Subject: [music-dsp] Loudness Maximizer
>> > Hi everybody!
>> > I'm trying to figure out how to write an effective loudness miximizer.
>> I've written a look-ahead limiter with a 1ms look-ahead time and a release
>> of 1ms, but it's very hard not to get pumping when I try to get the same
>> loudness as commercial records. If anyone knows how Steinberg, Waves and the
>> other companies do their limiters, I'd be very grateful if you could give me
>> some hints. Do they use clipping? Perhaps a combination of look-ahead
>> limiting, clipping and ordinary compression/limiting?
>> > I'm very grateful for any replies. Thank you very much in advance!
>> > Christofer Bustad
>> > dupswapdrop -- the music-dsp mailing list and website: subscription info,
>> > FAQ, source code archive, list archive, book reviews, dsp links
>> > http://shoko.calarts.edu/musicdsp/
>> dupswapdrop -- the music-dsp mailing list and website: subscription info,
>> FAQ, source code archive, list archive, book reviews, dsp links
>dupswapdrop -- the music-dsp mailing list and website: subscription info,
>FAQ, source code archive, list archive, book reviews, dsp links
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