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Re: Interpreting [movie currentTime]
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Re: Interpreting [movie currentTime]


  • Subject: Re: Interpreting [movie currentTime]
  • From: Quincey Morris <email@hidden>
  • Date: Tue, 25 Mar 2008 09:36:15 -0700


On Mar 25, 2008, at 08:50, Joseph Ayers wrote:

Tech Note 2138 http://developer.apple.com/technotes/tn2005/ tn2138.html states that this is AKA:

// ,,,dd:hh:mm:ss.ff/ts
which translates into:
days:hours:minutes:seconds:frames/timescale

But as I step through my movie the string that [movie currentTime] returns is of the form

0:00:00:05.315/2997
0:00:00:05.415/2997 in consecutive frames

Continuing Stepping, I see transitions like

0:00:00:06.2918/2997
0:00:00:07.21/2997
0:00:00:07.121/2997 in consecutive frames


Is 315 in the first instance, the current frame, or 3? If its 3, what is 15?
How do I translate this into a time in seconds?

The "/" here represents division, and the result is a time, not a frame number.


Your movie is 29.97 fps, so the frames are 100/2997 seconds apart.

The frame after 5.315/2997 is 5.(315+100)/2997 or 5.415/2997. Since 2918+100 modulo 2997 is 21, the frame after 6.2918/2997 is 7.21/2997.

Notice that if the numbers increased by 125 instead of 100, the movie would be playing at 2997/125 or 23.976 fps, another standard rate.

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References: 
 >Interpreting [movie currentTime] (From: Joseph Ayers <email@hidden>)

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