What is Lookahead?

ray1018 8 April 2008

I'm a Logic Pro user.
I saw the Lookahead setting at the bottom of Multiband Compressor (Multipressor) ~ from 0ms to 20ms and default is 5ms.

May i know how it work?
Thanks

FAQ

What is lookahead in pro audio?

Look-ahead is a process used for recording, mixing and mastering music. Its an option found in digital limiters and compressor plugins. When the look-ahead is set properly, it can improve the sound of a musical track. The object is to dial in specific frequencies and peaks that may not reproduce well in a recording (final mix). The goal of the look-ahead is to control excessive transient peaks while leaving other frequencies alone, thus, ultimately producing a smoother and louder mix or master.

The Lookahead knob sets the look-ahead time for the initial 'transient' stage. This allows the limiter to examine the incoming audio in advance and predict the amount of gain reduction needed to meet the requested output level.

Who makes a good lookahead plugin?

Ranking high on our list is the FabFilter Pro-L 2.

Comments

Is it something function like Attack?

ray1018 Tue, 04/08/2008 - 05:09

Is it something function like Attack?

I'm not using Logic and haven't used that compressor but the te

Robak Tue, 04/08/2008 - 07:07

I'm not using Logic and haven't used that compressor but the term "lookahead" usualy means that signal is delayed so it can be analysed by compressor. The longer the delay time is the more precise the analysis. For example, thanks to this function compressor "knows" when transients will occur in the signal.

Robak wrote: I'm not using Logic and haven't used that compress

ray1018 Tue, 04/08/2008 - 07:17

Robak wrote: I'm not using Logic and haven't used that compressor but the term "lookahead" usualy means that signal is delayed so it can be analysed by compressor. The longer the delay time is the more precise the analysis. For example, thanks to this function compressor "knows" when transients will occur in the signal.

Hey Robak,
Thanks for the info.
So, 'the longer the delay time is the more precise the analysis' means,gonna set the lookahead as much as it provide? for example, 0ms-20ms...i s'ld set it to 20ms?

Sorry for my fool question.
but need your hands.
Thanks

As I said I don't know that particular compressor so I cannot he

Robak Tue, 04/08/2008 - 07:35

As I said I don't know that particular compressor so I cannot help you much. I guess it's not as simple as just using maximum delay. Use your ears and included manual :wink:. BTW multiband compressors used by unskilled hands can do a lot of damage to your overall sound.

Yes - look ahead is as Robak describes it. In general, the long

Cucco Tue, 04/08/2008 - 07:50

Yes - look ahead is as Robak describes it. In general, the longer the look ahead the better, however, beyond maybe 5-10 ms should make no improvement.

Also - I agree with Robak in that using a Multi-Band compressor for mastering is usually a very bad thing. It's usually a very good sign of the worth of the ME when I see whether or not they use a MBC on a regular basis (or list it high on their equipment list).

I don't know of much that can't be accomplished with an EQ and Compression/limiting that would ever need to be accomplished with a MBC with some VERY rare exceptions (multi-band downward expansion for low-level noises, etc.)

Robak wrote: As I said I don't know that particular compressor s

ray1018 Tue, 04/08/2008 - 07:54

Robak wrote: As I said I don't know that particular compressor so I cannot help you much. I guess it's not as simple as just using maximum delay. Use your ears and included manual :wink:. BTW multiband compressors used by unskilled hands can do a lot of damage to your overall sound.

OK man.will check it out.Thanks anyway.
;)

For what it's worth..... I don't like look ahead limiters. The

RemyRAD Tue, 04/08/2008 - 23:22

For what it's worth..... I don't like look ahead limiters. They are important for proper peak control since it knows the peak is coming. But that really crushes the life out of your sound. Much more important in a broadcast application, or when cutting into lacquer. If anything, I turn off the look ahead feature in most of my software compressor/limiters. I want it to miss the incoming peak before it clamps down on my sound. This helps preserves transients.

In the days of VU meters, you never saw any peaks. But you knew your peaks were approximately 15 DB higher than your observed levels. But now everything has peak indicating meters taking a lot of the guesswork out of the transient transits travels.

You need both peak & RMS compressors/limiters, with and without look ahead.

I hope this peaked your interest?
Ms. Remy Ann David

RemyRAD wrote: In the days of VU meters, you never saw any peaks

Cucco Wed, 04/09/2008 - 05:18

RemyRAD wrote: In the days of VU meters, you never saw any peaks. But you knew your peaks were approximately 15 DB higher than your observed levels. But now everything has peak indicating meters taking a lot of the guesswork out of the transient transits travels.

You mean you didn't know the tricks for getting your VUs to read faster? WD-40 into the casing? Mounting the rack unit sideways to allow gravity to help the needles move faster? A helium-rich atmosphere in the studio to allow for lower air-pressure...

Besides, don't you know Remy, dynamics don't have any place in modern music? :-?
15dB peaks beyond RMS...please :roll:
Your music is only supposed to have 7-9 dB of dynamic range or it can't compete on the current market.

Don't worry - I know a couple recording schools in Maryland that will happily teach you these things. :wink:

When are you up for a beer in the near future? My treat.