Video with variable rate

Hello,
I use my cell phone (OPPO A74, Android) to film sequences which are then edited with shotcut.
When I upload a video I have the following message :
This file has a variable frame rate which is not ideal for editing. Proposal made (good): lossy I-frame-only H264 AC3 MP4
Is it possible to avoid this conversion or do I have to do it? If so, is the final result very degraded? Previously I used Windows Movie Maker and I never got this kind of message.
Could you share with me your experience on the subject? I tried exporting the video in FHD (1920x1080), it works. The file is certainly heavier but it seems to be of better quality.
Thank you by advance.
Regards.

This message is only a suggestion to convert to Edit Friendly.

The result would be something you need to experiment and find your own conclusions.

Shotcut, among other video editors export to a constant frame rate. While it may show 30fps, the actual frame rate is skewed to something like 30.002317 (instead of 30.000000). FPS = Frames per second. So here and there you’ll have a skipped or double frame in your video on your final exported video.

The conversion creates a new file, leaving your original untouched.

While your original is variable frame rate, Shotcut will only recognize one frame rate for the whole file which may cause issues with aligning filters and other media in the timeline.

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Thank you @Hudson555x for your detailed and very clear explanations !!
From what I understand, it is therefore rather recommended to follow the suggestions made by shotcut. All that remains is to position the cursor at the appropriate quality level/file size.
Regards.

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Most people don’t need frame-accurate detail in their edits. If you used windows movie maker then you also probably don’t need it.

I personally never convert variable framerate videos as long as they are not crazy bad (so 29 vs 30 ok, 16 instead of 30 is bad). I recommend you try it both ways to see if it works for you.

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Hello @daniel47,
Thank you for your feedback.
You are right the best way is to test and see the result. I chose resolution 1920x1080 (FHD) the file is not too heavy (about 2Go).
Here is the link to the vidéo :

Regards

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There is a caveat. Smartphones are unruly beasts that do whatever they want to do when it comes to encoding video. If one phone clip works, that isn’t a guarantee that future clips will work. VFR gives smartphones the freedom to skip frames for compression benefits or to cope with constrained processing resources. There is no predictable way to know which clips get huge VFR swings for one or both of those reasons.

Simply saying, keep in the back of your mind that if a clip is ever behaving erratically in Shotcut, or an export comes out choppy or with skips or inaccurate seeks, this is probably the reason. That clip should be converted to edit-friendly then try again.

The VFR unpredictability is why I use a dedicated camera instead of a smartphone for video. But I realize that is not viable for everyone. I’m just saying it’s a good use case for dedicated cameras.

The nice thing about Shotcut’s Properties > Convert feature is that it automatically replaces the timeline clips when it is done while also retaining their trim times, filters, and keyframes. So, make the video, export, and review. If there is a timing problem, convert and then review, as the timing could change very slightly. But after that, export result should be more predicable.

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Hello @Austin,
Thank you for your return of expérience. Of course a dedicated caméra is much much better. I did it with m’y mobile phone. Hère is the link to the final vidéo :

Regards

Hello @shotcut,
I supposed using convert function is the best way to optimise the vidéo. I had hésitation concerning the position of the cursor. I chose “good” (cursor positioned on the left side). Is it useful to move the cursor in the middle or to the right ? Huge increase of the size but is the quality much much better ?

Link to the final vidéo :

Regards

The middle and right options can be beneficial in two key scenarios:

  • high-quality videos from high-quality dedicated cameras, where all the detail and color need to be preserved for future color grading
  • super-low-quality videos that cannot survive another round of encoding, and therefore need what little data they have to be perfectly preserved

Most smartphone cameras are comfortably between those two extremes, meaning there isn’t a significant quality difference between the three options. So, the left option is best for smartphone video because it’s plenty good enough quality without consuming a large amount of unnecessary disk space.

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Hello @Austin,
Thank you for your (very clear and useful) comments.

Regards

Hi Fantomas,
I’m also having the same problem as you with the net video making application. How do you solve the problem?

Hello @antonyNguyen,
When I upload a group of videos in shotcut I have a message indicating variable rate, so I choose the option “convert” with cursor on the left side (if you want better quality move the cursor to the right, but you will obtain a huge vidéo). All vidéos are converted and renamed. Then I put all these new vidéos on the timeline and After editing (adding of text, …) I export the vidéo.

Here is the result :

Regards