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Finding the frame that corresponds to a time?

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This topic contains 1 reply, has 2 voices, and was last updated by  Han 4 months, 4 weeks ago.

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June 21, 2017 at 02:27 #11593

lchukoskie

Hello,

We are working on a validation project in which our “human coding” is compared with an algorithm. For irritating reasons, the algorithm needs to know the frame, as opposed to the time, an event occurs. We have the videos coded with marks in time. Does anyone know how to get ELAN to spit out the corresponding frame? It is (unfortunately) not as simple as dividing by the expected framerate. Does ELAN have access for frame-based information?

Thank you!
Leanne

June 28, 2017 at 11:07 #11610

Han

No, ELAN does not have direct access to frame numbers. Depending on the platform, ELAN uses different “native” media players or frameworks and in most cases getting or setting the media time is done based on milliseconds or nanoseconds. I’m not sure if any of the players has a function to get the frame number, but ELAN doesn’t use it.
The closest is probably the export in SMPTE format (hour:min:second:frame) but that’s probably not what the algorithm expects.

I guess it depends on the frame duration of the recordings, but in principle dividing the millisecond time values by the frame duration should be fairly accurate and allow to compare with the algorithm? And, better maybe, if you multiply the frame number (of the algorithm) with the frame duration, it is possible to validate based on time information? But maybe I don’t fully understand the situation.

-Han

PS apologies for the delay, the ELAN forum would have been a better place for this post, it is monitored more actively

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