Trying to understand CMTime and CMTimeMake

lilzz picture lilzz · Oct 23, 2010 · Viewed 70.3k times · Source

1) CMTimeMake(1,10) means duration of 1 second and timescale of 10, or 10 frames per second. This means 1s duration of video with 10 frames?

2)

CMTime lastTime=CMTimeMake(1,10);
CMTime frameTime=CMTimeMake(1, 10);
CMTime currentTime=CMTimeAdd(lastTime, frameTime)

= (2, 10) ?

2 seconds of video and with 10 frames per second of the currentTime?

Answer

Peter DeWeese picture Peter DeWeese · Oct 23, 2010

1) CMTimeMake(1,10) actually means a value of 1 and a timescale of 10. They are a numerator and denominator, so it is 1/10 of a second, not 1 second.

2) The result will be like CMTimeMake(2, 10), which is 2/10ths of a second.