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Switching layer via audio keyframes/Sound Keys?

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Ike Hanson
Switching layer via audio keyframes/Sound Keys?
on Sep 21, 2010 at 9:13:08 pm

Is it possible to use an expression to allow either the built in audio keyframer or sound keys to switch the visible layer (say, out of a choice of 4 different layers) to the beat of the music? This would be very useful for music video editing, as I often require cuts that are precise and to the beat, and often not requiring much in the way of decision as to which layer is selected.

Thanks in advance if anyone can help!


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Ike Hanson
Re: Switching layer via audio keyframes/Sound Keys?
on Sep 21, 2010 at 9:27:38 pm

Thanks, I was hoping to combine the first one with some other idea, but I really have no experience with expressions and am not sure exactly how to create the most effective calculation.



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Cassius Marques
Re: Switching layer via audio keyframes/Sound Keys?
on Sep 21, 2010 at 9:29:00 pm

You can use soundkeys to generate values according to the waveform (let's say beat).

and use these values to drive the opacity of a number of layers. For example, generate values between 1 and 100. And through expressions tell one layer to be 100% visible when the value is between 1-25. The other layer to be visible as the value is 25-50 and so on(taking 4 layers as example).

As the number os layers go up, it can get tedious, since it's one "if-else" expression to each layer, so i'm gessing it can compensate (opposing normal editting) if the audio is long and there aren't many layers.


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Dave LaRonde
Re: Switching layer via audio keyframes/Sound Keys?
on Sep 21, 2010 at 9:44:47 pm

[Ike Hanson] "I often require cuts that are precise and to the beat"

....and that's the tough part to know if you use something like soundkeys. Yes, you can isolate frequencies and audio levels. But do you actually have the beat, or something that's kinda-sorta close? You don't know until you use the generated keyframes for something.

What if the bass player did some syncopation, and you were isolating the bass drum for the beat? Whoops! You just wasted a lot of time and effort. What if there's a section in the music with just ostinato strings? The beat still exists, but just try finding it! There are just too many audio variables involved to get a truly reliable, automatically-generated beat calculation.

Your best bet: just cut together a tiny --120x120 would be just fine -- video of alternating black and white, cut on the beat. You can add it to AE as a visual reference: there's no guessing or scrubbing involved . You always know where the beat is. Then it becomes a simple matter of trimming and and out points, splitting layers and arranging layers in AE.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Walter Soyka
Re: Switching layer via audio keyframes/Sound Keys?
on Sep 21, 2010 at 10:09:58 pm

I absolutely agree with Dave -- I doubt this can be done automatically and effectively. You really don't make any editorial decisions, just purely random cuts on the beats?

Another alternative method for marking the beats is hitting the period key on the numeric keypad to start an audio preview, then tapping the asterisk key on the numeric keypad to add markers to the composition. It's easy to snap items on the timeline to the markers.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Ike Hanson
Re: Switching layer via audio keyframes/Sound Keys?
on Oct 6, 2010 at 7:20:12 am

Thanks for the replies, I should have made it clear that all of the clips I intended to use were just singing performance clips, and therefore no decision of editing was required, merely just music video edits. I shall use the keyframing tool in future, but it would have been interesting to have been able to automate the process!



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