Topic: First Half Video Only

Hi all,

Not sure if a bug or something I'm doing incorrectly. Occasionally when I try to open a video file it will only show me the first 1/2 of the video not the full length. I check the raw file in a media player outside Kinovea and it is fine. As soon as I load it into the viewer, it just shows the first 1/2. This has happened on a few occasions but not consistently.

Any insight?
Thanks!

Re: First Half Video Only

It is the first time I hear of this. Could you share a sample file please?

Re: First Half Video Only

Thanks for the sample.
It is one of those files where the first frame of the video has a negative timestamp, this throws off some calculations… Can you share what camera or process has generated the file?
It's probably fixable but needs care to not break other things in the process.

Re: First Half Video Only

All the videos are filmed with either iPhone or android equivalents.

Re: First Half Video Only

It's interesting to compare the behavior with version 0.8.15 which used a different way to get the timestamps. In that version the duration is computed wrong and the video goes all the way but then it loops back before the stated duration and the playhead continues and never loops back. It also completely breaks the working zone selector.

Re: First Half Video Only

Stepping frame by frame in debug, the timing info inside the file is fairly consistent with having just 59 frames, somehow the last 20 frames or so are not reachable by normal means.

Is there a player where it fully works? I think the file is broken. When I open in VLC it just freezes on the first frame. In media player classic it shows the entire video but the timeline jumps back at zero halfway through. In the Windows 10 media app it shows the whole video but the timeline reaches the end after maybe a third of the video so seeking with the timeline is even worse. In the classic Windows Media Player the timeline is also completely confused. Some of these players may have less strict requirements on frame-to-timestamp coherence when they just want to playback the video. For frame by frame and accurate time computation Kinovea needs more consistency.

Did you use a particular application or mode on the phone to record it or did you modify it afterwards to trim the endpoints or other post-process? Like maybe a pre-roll or slo-mo feature?

Re: First Half Video Only

Here is our workflow:
1) Athlete films the video on their phone camera. They just use whatever the normal camera is on normal speed, no special apps, no slo mo.
2) They email it to me, I open it on my Dell using the "Films & TV" app to take a quick check I tagged it correctly. That's just the program that was on my Dell.
3) I open it on Kinovea and analyze it.

The video clip I sent to you plays perfectly on the Films & TV app on my Dell. I only have this issue with about 10% of the videos. I'm not sure what is different about these ones vs the others.