AE ENHANCERS

So, I'm getting in a bit of a muddle here, and hoped somebody could help me leap over the last hurdle.

Basically, I want to synch' the Audio to the speed at which the video image is displayed. So, when the track is LOUD, the image speeds up, and when the track is quiet, the image slows down. I realise the image will be jumping ALL over the place, but that's the look I want.

So, to do this I've turned the audio into keyframes (right click on the track > Keyframe Assistant > Turn Audio into Keyframes), which creates a beautifully little null. I can do this to the treble and bass separately if I wish, but for now I've created a single null for both.

I then link the slider for Both Channels within the null to the position of the null, so that the null moves with each beat. I can link the null to the scale of a video layer if I so chose, with no problem, adding a small expression to ensure the scale is always above 100 (( linear(value,0,100,100,140) )).

But what I want to do is link the Slider within Both Channels of the null to the Speed at which a video layer is played. Currently, if I do this through Time Remapping, I just get a video that bounces around through the corresponding timecode, but what I want it to do is play faster and slower. Does anybody know the expression I need in order to do that?

Thanks a ton.

Use the audio as a multiplier to normal playback rather than the value itself. Other than that you will have to reduce the number of keyframes to the most distinct ones, access the keyframe values directly and interpolate on your own. All of that can be found as an example (for markers) on Dan Ebberts' website.

Mylenium

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[Pour Mylène, ange sur terre]

I don't think you can use the audio amplitude (or some "linear()-ized" value to change its range) as a timeremap multiplier because the animation will jump forward and backward, not slower and faster.
You need an expression that loops through the comp or layer duration and maintains a counter (say a number of frames) that increases at each frame by an amount based on the audio amplitude (you also need the range of your audio, the min max values as references for calculation).
I've got a script that does this job. After converting your audio to keyframes, you select your video layer and that's it (there is a controller to specify how "intense" the acceleration will be).
It's not on my website but here is a demo. The basic animation is a camera flying through some text layers (the names of the 70 top posters on aenhancers) along the Z axis. The audio amplitude of the track influences the speed of the camera movement (actually it drives the timeremap property of the precomp).

If you're looking for something like that, I can make the script available...
audioAmp_to_videoSpeed

Thanks to both of you. Really appreciate your thoughts.

Nab - yeah, when using the amplitude data for time remapping, I get a video that continually jumps around, which is an interesting effect in itself, but not what I had in mind. I'm VERY interested on getting my hands on your script. The demo vid displays an effect that is exactly what I'm looking. Good stuff (and great choice of music)

If you'd like to keep the script quiet, we can discuss this over email (richy@outcast.tv) - although I know other users of Ae Enhancers would love to see it too!

The script can be downloaded here

Usage:
1. convert your audio to keyframes
2. select your video or precomp layer
3. execute the script

A null layer and a parameter called "Max Forward" are created at the top of the comp, this parameter controls the "speed"...

Nab - that's amazing.

The script works extremely well. It's a tad chaotic with loud music (aside from using Audition or Soundbooth to change the Bass, or Treble, etc before I turn the audio into keyframes, would I be able to alter the chaotic nature with a linear(value, _, _, _, _)) expression in there somewhere?), but it works fantastically well in most occasions, especially when there's a distinct beat and lots of silences.

Thanks a ton, and well done! If I ever use it in a music video (like I intend to), I'll credit you, and even send you some cash if I have a budget!

You could use a "smooth()" expression on your audio data (see the doc for usage) or play with The Smoother (from the Window menu). Sometimes this helps.