user15988: I am making a home vacation video set to music. The song I selected has a BPM of 90.
I want the video clips to match the beat, so for example, every time you hear the beat a new video clip begins. How would I determine how long the video clips should be? If there is an equation I can use for other BPMs as well that would be great.

user3908: If you want a new image at every beat, start with the frame rate of your video. 30 frames per second gives 1800 frames per minute. Divide that by 90 to get the number of frames per beat, in this case 20. So if you change the image every 20 frames the pace will be the same. You do have to align the cuts with the beat; just matching the pace is only part of the battle.
In the general case:
(FPS x 60) / BPM = number of frames per beat

15988: <p>I am making a home vacation video set to music. The song I selected has a BPM of 90.</p>

<p>I want the video clips to match the beat, so for example, every time you hear the beat a new video clip begins. <strong>How would I determine how long the video clips should be?</strong> If there is an equation I can use for other BPMs as well that would be great.</p>
 3908: <p>If you want a new image at every beat, start with the frame rate of your video. 30 frames per second gives 1800 frames per minute. Divide that by 90 to get the number of frames per beat, in this case 20. So if you change the image every 20 frames the pace will be the same. You do have to align the cuts with the beat; just matching the pace is only part of the battle.</p>

<p>In the general case:</p>

<p>(FPS x 60) / BPM = number of frames per beat</p>
