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Marked frames dont always auto-advance post and replies

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Marked frames dont always auto-advance - Jun 19 at 6:31PM
kim reynolds
3 Posts

I'm green to this so perhaps this issue is simply due to my being a newbie... When I manually mark an object in a frame, usually the video automatically advances to the next frame. But sometimes it doesn't and remains the same one. If I click on it again (a second time, at the same spot), it will usually then advance, but that second click results in a new row of t,x,y data, which has a slightly greater timestamp (even though it was the same exact video frame). The frame number also increases by 1. This has me definitely confused. What am I doing wrong or misunderstanding?


Replies to Marked frames dont always auto-advance

Re: Marked frames dont always auto-advance - Jun 20 10:51AM
Douglas Brown Avatar
Douglas Brown
231 Posts

I think that for some reason some frames are duplicated in your video. What is the camera? Can you step through the video frames in another application?

Another possibility is that the Xuggle video engine cannot handle the video codec. In this case you might try converting the video to a different format--Xuggle does well with FLV, for example.  There are a number of free video converters out there.

Hope this helps.  Doug



Re: Marked frames dont always auto-advance - Jun 20 2:08PM
kim reynolds
3 Posts

Indeed, it seems there are duplicate frames sprinkled throughout my original video - hmmm. I've been using a GoPro. Is this a GoPro characteristic?



Re: Marked frames dont always auto-advance - Jun 20 6:03PM
Douglas Brown Avatar
Douglas Brown
231 Posts

I haven't heard of this problem with GoPro before. Have any of you GoPro users out there? Doug


> Re: Marked frames dont always auto-advance
>
> Indeed, it seems there are duplicate frames sprinkled
> throughout my original video - hmmm. I've been using
> a GoPro. Is this a GoPro characteristic?



Re: Marked frames dont always auto-advance - Jun 21 2:04PM
kim reynolds
3 Posts

Thanks, Douglas for your help. It was my dumb of course - the original GoPro file was too big (I guess) to load, so I cut it in half in a video editor and in doing that, I inadvertently changed the frame rate from the original 24 to 30. That's where the repeated frames came from that confused me. The video editor had automatically inserted them.



Re: Marked frames dont always auto-advance - Jun 25 4:50PM
Paul Nord
19 Posts

Kim,

Yes, be very leery of video editors.  Even if you aren't doing something like changing the frame rate they can drop or repeat frames.  I suspect that they do this to optimize data rates.  But that's really not what you want for physical analysis of a video.

A more famous example is the "Thrown Bat Home Run."  Google that phrase and you'll find Todd Frazier's home run a 2012 game against the Cincinnati Reds.  The network's official high speed video actually includes a dropped frame.  That's difficult to analyze, but not impossible.

Paul



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