“I enjoy scoring music to video but get into math hysteria when adding and subtracting time code. Do you have any tips?”
Oh boy, have I been in your shoes! Adding and subtracting SMPTE time code doesn’t take a rocket scientist, but it is a brain breaker because there are 60 seconds in a minute instead of a 100, and there are 30 frames/second (or 29.97, or…) instead of a number that would be easier to multiply like 10 or 100. Again, not a big deal but I’ve come to a complete stand still in my studio when I’ve had to figure out how many minutes, seconds and frames I had to cut out of a shot or music cue when using SMPTE time code. The following is something that I have read in several books, so while I didn’t invent this tip I have used it and can say that it works every time.
The problem arises when you need to subtract a larger number from a smaller number within a given time field, i.e. frames, seconds, minutes or hours. Well, like we all learned in elementary school, just borrow from the next higher time increment. Let’s look at an example.
This:
01:23:20:17
-00:26:19:23
00:57:00:24
Is the same as:
00:83:19:47
-00:26:19:23
00:57:00:24
All we’ve done is borrow from the next higher time increment.17 frames became 47 because we borrowed one second (which equals 30 frames) from the seconds field which forced the seconds field to become 19. After you’ve applied this throughout the equation, simple arithmetic is all one needs to come up with the difference.
After you’ve tried this a few times, I think you’ll get used to it.