Video frame boundaries
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Video frame boundaries
I'm not sure if this is possible, but I'll ask anyway.<br><br>I'm doing some annotating of rapid movements - in this case, eye movements. Most of the time, the movements take less than one frame to complete, so the best I can do is to line up on the video frame boundaries.<br><br>I've noticed that +F and -F don't really move from the start (or end) of one frame to the start (or end) of the next. All they do is advance the timeline by the width of a frame. I.e. if I am positioned 14 mSec prior to the end of one frame and I click +F, I move to 14 mSec prior to the end of the next frame. It is a bit of a nuisance having to align a great many events to exact frame boundaries. <br><br>So - Is it possible to detect frame boundaries from within ELAN? Or don't the display engines give you enough information to do that?<br><br>What I'd like (if it is at all possible) is a way of "locking" onto the video frame boundary - even if it is semi-manual, and then staying on the boundary - kind of like a "jump to grid" function in an architectural drawing program. It would be no big deal to zoom to 1000%, find a frame boundary and then tell ELAN. In fact, if the display engines are 'unstable' (i.e. lose reference if you jump around too much), I wouldn't mind having to re-lock every now and then.<br><br>Is any of this possible?<br><br>Bruce<br>
Re: Video frame boundaries
It is true, the default behaviour of frame forward/frame backward is jumping forward/backward with the duration of a single frame. This is for historic reasons. But there is an option to change that behaviour, under: Edit -> Preferences -> Edit Preferences and then the Media item. There is a subheader, Media Navigation, that allows to change this behaviour to always jump to the beginning of the next/previous frame. For this to work, it is required that the player framework can inform about the exact frame duration. And if the frame duration is something like 29.97 ms you may notice rounding effects.
To be sure, this is only for positioning the media playhead and can thus only be used for new annotations. There is no function (yet) to automatically adjust existing annotations such that they exactly align with video frame boundaries.
-Han
Re: Video frame boundaries
I'm not sure if this is possible, but I'll ask anyway.
I'm doing some annotating of rapid movements - in this case, eye movements. Most of the time, the movements take less than one frame to complete, so the best I can do is to line up on the video frame boundaries.
I've noticed that +F and -F don't really move from the start (or end) of one frame to the start (or end) of the next. All they do is advance the timeline by the width of a frame. I.e. if I am positioned 14 mSec prior to the end of one frame and I click +F, I move to 14 mSec prior to the end of the next frame. It is a bit of a nuisance having to align a great many events to exact frame boundaries.
So - Is it possible to detect frame boundaries from within ELAN? Or don't the display engines give you enough information to do that?
What I'd like (if it is at all possible) is a way of "locking" onto the video frame boundary - even if it is semi-manual, and then staying on the boundary - kind of like a "jump to grid" function in an architectural drawing program. It would be no big deal to zoom to 1000%, find a frame boundary and then tell ELAN. In fact, if the display engines are 'unstable' (i.e. lose reference if you jump around too much), I wouldn't mind having to re-lock every now and then.
Is any of this possible?
Bruce
Re: Re: Video frame boundaries
As of version 3.4.1, there is a preference that says "Create annotations aligned with video frames". I suspect that is what you want.
Release of ELAN 4.3.0
