skips frames

[rcoenen]

Hi,

I tested your code with:
Google Chrome 48.0.2564.82 (Official Build) (64-bit)
Revision 6b53888d9893e17210eb2ec98d8e9f8d5ea8a5d1-refs/branch-heads/2564@{#564}
OS Mac OS X

Problem: start at frame 0 (STMPTE 00:00:00:00) then press SHIFT+right arrow 11 times.
The calculated SMPTE timecode shown is now 00:00:00:11 but the video frame shown is 00:00:00:10.
It has skipped a frame.

Press SHIFT+right arrow again and now both calculated and video frame SMTPE are at 00:00:0012

To be frank, this could be a bug in Chrome. I am not sure at all if this is a problem with your code, but as it stands it des not work correctly.

[alejandrocoding]

Hello,

I just hit the same issue, I see this ticket still open since 2 years now, is there any info about it? workaround? reasons why does this happen? I am facing same problem in my app and I'd love to know more on this.

Thanks,

[alejandrocoding]

I just tested on Safari and same error so I would say it's not browser related.

One step to reproduce this would be:

1. Open http://allensarkisyan.github.io/VideoFrameDocs/
2. Change Frame Rate to 30
3. Press next just once.
4. See the image attached.

[rcoenen]

I think it is browser related - the Javascript code seems fine... I also think that all the big browser vendors have made the same mistake in their implementation. They all copied Chromium I suppose and I suspect this is where the problem lies.
Would be worth testing in Opera maybe or some other browser that isn't a Chromium clone under the hood.

[alejandrocoding]

Tested on Firefox and same result. I think it's a problem about Web standards limitations, see this:

http://www.inconduit.com/smpte/

[rcoenen]

@ialex90 funny - tat is the test framework I originally wrote while at the BBC. It was intended for non-drop-frame (PAL). This sample you've sent has modified the code to work with drop frame/NTSC. Unsure if this was ever intended to work.

[tomByrer]

I think it's a problem about Web standards limitations, see this:

Might be more of a CPU float error that JavaScript does not attempt to fix, so you have to use float workarounds in JS.

[moha-osama]

I had been facing the same issue, but then I noticed this line
VideoFrame(a); this.obj = a || {}; this.frameRate = this.obj.frameRate || 24;
This line sets the frame rate to 24 when no frame rate is passed to the object or when it's undefined. Therefore, you must ensure that you pass the frame rate.
In my case, I had declared the configuration object before importing the video file, so there was no frame rate, and it defaulted to 24. You can reassign the configuration object after importing your video file.

hope that's help