user867: What's one way to get a strobe flash effect in video (you know, virtually, in software) that's synchronized to the beat of a music track?
Or for that matter, how do I synchronize ANY effect with music?

user2352: Assuming that you're using AE...
The old fashioned way: 

Select your layer, hit 0 (on the numeric keypad) to do a ram preview
Wait till the preview is loaded into the ram
When the preview begins to playback, hit * (on the numeric key pad) at each beat
As soon as you stop playback, you'll have a marker at each beat
now you're ready to begin key framing according  to the beats

Red Giant's - Trapcode Sound Keys is probably the best plugin out there for automating it.
http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/

user-1: Trapcode's Sound Keys will do the job:
http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/
From the promotional text:

Now it's easy to synchronize motion and sound in After Effects. With
  Trapcode Sound Keys, your audio-intensive animations no longer require
  extensive keyframing. Visually select parts of an audio track and
  convert them into keyframes, syncing footage with audio using
  amplitude or frequency ranges. Sound Keys is applied as a regular VFX
  effect, so you can save its settings with your project, generate
  keyframes into output parameters, and link keyframes to expressions.
  The possibilities are huge, just like the beat.

By using the generated key frames you can hook them up to almost any effect or behavior that you want.
A basic example of using this plugin to drive a few "strobes":




867: <p>What's one way to get a strobe flash effect in video (you know, virtually, in software) that's synchronized to the beat of a music track?</p>

<p>Or for that matter, how do I synchronize ANY effect with music?</p>
 2352: <p>Assuming that you're using AE...</p>

<p>The old fashioned way: </p>

<ul>
<li>Select your layer, hit 0 (on the numeric keypad) to do a ram preview</li>
<li>Wait till the preview is loaded into the ram</li>
<li>When the preview begins to playback, hit * (on the numeric key pad) at each beat</li>
<li>As soon as you stop playback, you'll have a marker at each beat</li>
<li>now you're ready to begin key framing according  to the beats</li>
</ul>

<p>Red Giant's - Trapcode Sound Keys is probably the best plugin out there for automating it.
<a href="http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/" rel="nofollow">http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/</a></p>
 -1: <p>Trapcode's Sound Keys will do the job:<br>
<a href="http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/" rel="nofollow">http://www.redgiantsoftware.com/products/all/trapcode-sound-keys/</a></p>

<p>From the promotional text:</p>

<blockquote>
  <p>Now it's easy to synchronize motion and sound in After Effects. With
  Trapcode Sound Keys, your audio-intensive animations no longer require
  extensive keyframing. Visually select parts of an audio track and
  convert them into keyframes, syncing footage with audio using
  amplitude or frequency ranges. Sound Keys is applied as a regular VFX
  effect, so you can save its settings with your project, generate
  keyframes into output parameters, and link keyframes to expressions.
  The possibilities are huge, just like the beat.</p>
</blockquote>

<p>By using the generated key frames you can hook them up to almost any effect or behavior that you want.</p>

<p>A basic example of using this plugin to drive a few "strobes":</p>

<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/_ptzCbhk0vE?start=0"></iframe>
            </div></div></p>
