Matching beats per minute and frame number

Googlefood only…

You have:

  1. BPM: Beats per minute for some music
  2. FPS: Frame Rate of your video

You want to (a) figure out what beat is at a certain frame, and (b) decide if a certain frame is on a beat.

Math:

Beat Number(FrameNum) = Integer( ( FrameNum / FPS ) * ( BPM / 60 ) )

Is a Beat Frame(FrameNum) = BeatNumber(FrameNum) – BeatNumber(FrameNum – 1)

If (Is a Beat Frame(FrameNum) ) == 1, then it is a beat. 0 if it’s not a beat.

Example:

Song is 202 bpm, frame rate is standard SMTP Drop-Frame; what about frame 24?

BeatNumber(24) = Integer ( ( 24 / 29.97 ) * ( 202 / 60 ) )
BeatNumber(24) = Integer ( 2.696 ) = 2

IsABeatFrame(24) = BeatNumber(24) – BeatNumber(23)
IsABeatFrame(24) = 2 – 2
IsABeatFrame(24) = 0

This entry was posted on Tuesday, December 1st, 2009 at 1:51 pm and is filed under googlefood. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

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