Choppy video

Hello,
this issue is not new, but I did not find a solution here.
My video is: 29,97 pics/s - 35349 kb/s - Codec H.264/ AVC / MPEG-4 AVC / MPEG-4 part 10

It is choppy while playing in Shotcut and also the exported file.
I tried:
a) converting into an better format for Shotcut
b) no parallel work
c) different qualities and formats
But still choppy.

Some hints would be helpful. :slight_smile:

Hello @AbsBegin

Can you answer a few questions?

  • Computer specifications (CPU, Ram, OS: Win/Linux/Mac, Drives: HDD/SDD/NVME/other)

  • Shotcut version (Help - About Shotcut)

  • Video Mode used (If you have a timeline, click on Output, the Properties).

  • Display Method (Settings - Display method)

  • Source Video information

      1. Click the three little lines
        shotcut_2020-12-29_04-18-34
      1. Click More Information
        2020-12-29_04-19-02
      1. Click Save (Drag/drop this file you saved into this reply window, or use the file uploader icon.
        shotcut_2020-12-29_04-19-22
  • Export. Did you try the “Default” preset without changing anything in Advanced? If you did enter Advanced, what settings did you change?

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If it’s choppy in the export too, then the Video Mode is probably something lower than 29.97fps. Or the video clip was slowed down by a significant amount and there aren’t enough source frames to look smooth. (@Hudson555x‘s post has a link with more information about checking Video Mode.)

Hello Austin,
thanks. The fps and the speed are the same as in the original.

Best Regards
AbsBegin

What is the video source? Cell phone, .MTS file, etc? If the file is variable frame rate, there can be seeking issues that cause stutter in the export. We kinda need the rest of the information Hudson requested at this point.

Hello Hudson555x,
thanks for the answer.
one more info: videos I made by my camera works, only videos I made by my drone are choppy. Thus it depence on the imported video. When I look the source video in VLC it is not choppy.
Here are the specifications and/or answers to your questions (in German, but I hope you understand it by the units):

  • Computer specifications / Win10 Home / AMD Ryzen 5 3500U with Radeon Vega / 4 Cores / Mobile Gfx 2,1 GHz / RAM 8GB / 64 Bit / SSD

I hope it helps.

Best Regards
AbsBegin

one more Info: in Openshot (which I uninstalled) it was the opposite - videos I made by my camera did not work, but videos by my drone worked.

Could you include source video information for the camera video like you did for the DJI? Shotcut has an Automatic mode where it sets the timeline to the same settings as the first video dropped onto the timeline. I suspect differences between the camera and the drone. If true, then which one is choppy depends on which one was dropped onto the timeline first.

Also, did Shotcut ever prompt about “this video needs conversion to Edit Friendly” when adding a video?

Hello Austin,
I tried it also with only the drone video in a new project, but also choppy. I also converted the video in Shotcut - still choppy.
Enclosed the camera video info and the converted video info.
Source-Video-information-camera.txt (2.5 KB) Source-Video-information-converted.txt (1.7 KB)

thanks

The camera and the drone have different frame rates. The camera is 25fps and the drone is 29.97fps. They are not going to play nice on the same timeline. Either the 25fps video will have frames duplicated up to 29.97fps, or the 29.97fps video will have frames dropped down to 25fps. Both methods will create stutter. The real solution is to have both devices use the same frame rate, but that may not be an option as it appears one is PAL and the other is NTSC.

This tells me the Video Mode is set to 25fps. Frames are being dropped from the drone video to fit. One option could be setting the speed of the drone clip to 0.8333x which would slow it down enough to use all frames and restore internal timing.

yes - I changed the export file to 29.97 fps in advanced (only the drone file), but it is still choppy (see pic)

The Video Mode is still 25fps. Video Mode is the native format of the timeline. It is not overridden by the Export screen. The Export screen is an interpolation of the Video Mode, with all the problems that come with interpolation, including stutter. Video Mode is set as follows:

Ideally, the Video Mode and the Export screen will have the same settings. If not, interpolation and potential problems will happen. In the case of the drone video, frames are being dropped to get it down to the 25fps timeline rate (Video Mode), then frames from the 25fps timeline are being duplicated to get back up to the 29.97fps export target. This creates stutter.

Unless the files straight out of the two devices are the same frame rate, one of the two videos will be choppy (assuming 1.0x playback speed) because one video must be interpolated to match the other. That means dropped or duplicated frames which create stutter. The files you currently have are not frame-rate compatible with each other.

A workaround is to slow down the faster video (the drone) to match the frame rate of the slower video.

ok - I created a new project with only the drone video and the project setting on 29,97 fps. The Shotcut screen is still choppy, but the export file is now good, if I view it in VLC :+1: :slight_smile: .
Tomorrow I will slow down the drone video to 0,8333x.
Is there also another option?

Thanks

Excellent!

There are ways to generate in-between frames artificially. The general term is Optical Flow processing. But it is error-prone and slow. There is also depth-aware processing (DAIN) to improve on it, but still error-prone and slow and requires pretty beefy GPUs. These techniques never look as good as the real thing. The best look is when devices capture at matching frame rates from the start (unless there is intention to speed up or slow down a clip of course).

There is also a technique called 3:2 pulldown (or telecine) that converts 24fps movies to 60fps interlaced for television. I’m not sure how well it would convert your 25fps camera footage to 30fps progressive, but it might work for shorter clips.

Here’s a brief analysis of optical flow along with notes on when it works and when it doesn’t. However, Shotcut does not perform optical flow processing. This would have to be done with an external program like Premiere or Resolve or slowmoVideo, then bring that new video into Shotcut for editing.

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Thanks Austin,
I understand now the problem and how to avoid it - best is everything with the same fps.
Today I slowed down the drone video (from 29,97 to 25 fps)
and it works :star_struck: :+1:
Both work - the Shotcut viewer and the exported file - genial.

That’s it - super - 1000 thanks

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