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Frame (in)accuracy


Pete31684

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I've just downloaded the latest beta version. Website says it's 13.38, it displays as 13.37 so I'm guessing it's one of those two.

Frame accuracy is still wrong (remember, this is after over seven years now), doesn't appear to have been touched, so it's obviously not one of the issues that comes under the banner of "work done under the hood". It's also clearly something NCH don't consider to be very important.

Frame accuracy on a video editing package is of absolute, utmost, fundamental importance. Without guaranteed frame accuracy, a video editing package really isn't a video editing package at all. It's just something that will nail a few video clips and stills together, with no consideration to timing.

I liken it to a tape measure. It doesn't matter how many brilliant features it gets such as auto pay out and rewind, variable speed rewind, laser markers, built in GPS etc, if the inches/mm markings are wrong, the entire gadget is utterly useless.

Think of frame accuracy as the inches/mm. If they are wrong, the entire software is utterly useless. I simply cannot use it at all for my purposes. Pity, as I like the rest of it.

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On 5/10/2023 at 11:12 AM, borate said:

Chances are that the devs weren't aware of the issue until it was recently brought to their attention.

It would be nice to believe so. I've reported bugs relating to this issue at least 25 times since 2016. They occasionally fiddle with it, sometimes fix part of it, but in the process introduce another bug directly related, but slightly different. As far as I can tell there hasn't been a single version without a bug of one sort or another directly related to frame accuracy.

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On Beta 13.39 they've done some work on the frames. Some work. But it's still not right.

Single stepping through the frames (on 30 fps) now correctly shows the relevant frame, forwards and backwards so that's an improvement. However, on any frame that ends in 33ms the "next" frame is always wrong. It shows the current frame and the next frame as being the same frame.

To clarify that, set it to "show previous and next frames", the "next" frame is always wrong on a 33ms interval. It shows the current frame as also being the next frame. The other two (at 00ms and 067ms) are correct (this bug existed previously).

Further, when stopping play, the previous and next frames are not updated. It displays what they were last at before hitting play (this bug also existed previously).

Also, when stopping play, the time counter bears little to no relation to the actual time of the frame being displayed. Tapping next/previous frame will often have it jumping substantially in order to correct itself. I've seen it as far out as 200ms - that's six frames! (and this bug also existed previously).

So, in summary, a small improvement, but still a long, long way to go.

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On 5/20/2023 at 6:24 PM, Pete31684 said:

Single stepping through the frames (on 30 fps) now correctly shows the relevant frame, forwards and backwards so that's an improvement. However, on any frame that ends in 33ms the "next" frame is always wrong. It shows the current frame and the next frame as being the same frame.

To clarify that, set it to "show previous and next frames", the "next" frame is always wrong on a 33ms interval. It shows the current frame as also being the next frame. The other two (at 00ms and 067ms) are correct (this bug existed previously).

I have tried a few different files and found that it's actually the video themselves have duplicated frames. I.e. frame 33 and frame 67 are the same. This could happen if the video is re-encoded by a video editor by forcing a constant frame rate.

I tried some original videos directly from cameras or computer rendered, they don't have this issue.

BTW: The stopping bug will be fixed for next release.

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12 hours ago, c_major said:

I have tried a few different files and found that it's actually the video themselves have duplicated frames. I.e. frame 33 and frame 67 are the same. This could happen if the video is re-encoded by a video editor by forcing a constant frame rate.

I tried some original videos directly from cameras or computer rendered, they don't have this issue.

That simply doesn't explain what is seen.

If it was the video itself that had duplicated frames, they would also show as duplicated in the "previous" and "current" frame. They do not. Only the "next" frame is wrong. They would also show duplicated frames in other software packages. They do not. Only VideoPad "next" frame gets them wrong. Nothing else.

The file I am using was manually generated (in Express Animate as it happens). It consists of individual frames that simply contain the time and frame number. It was created at 30fps. No re-encloding, no frame rate conversion. The results are as follows (you'll have to put it into a text file to get the columns right):-

Time previous current next

167 04 05 06

200 05 06 07

233 06 07 07 <- this is wrong

267 07 08 09 <- where has frame 08 gone?

300 08 09 10

333 09 10 10 <- this is wrong

367 10 11 12 <- where has frame 11 gone?

It is definitely a bug in VideoPad, not a currupt video file.

-0-

Download the H.264 file from here...

https://archive.org/details/VideoTestFiles/1024X76830FpsPhotoJpeg75.mov

Single frame step through that, you'll see the bug in all its glory.

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If you're referring to 'stuck' preview on rewind when dragging the red scrubber to the left, evident in the "test.cut video" sequence, then that's a known issue.

Advance/retard frame button or arrow key action seems fine here, as shown in my above video.

This probably should be a separate thread,😊

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