Stuttering Footage - How to solve?

[MelleBax]

Hi everyone,

I have some 4K drone shots that are very smooth, but after editing very stuttering.

The original footage is shot in 4K 29,97 fps with a bitrate of +/- 58.000 kbps.
The final video is 4K 29,97 fps as well, and I tried different bitrates (11,000 and 185,000), as I had to solve another quality issue in my edit.
I've tried exporting in x264 and Voukouder MOV, but it's all stuttering.

Attached you will find a part of the final video I'm editing with the stuttering.

I have no idea why there is stuttering in the final edit. Is there anyone that can help me out?

Would be much appreciated
Many thanks in advance!

Melle

[poisondeathray]

Hi everyone,

I have some 4K drone shots that are very smooth, but after editing very stuttering.

The original footage is shot in 4K 29,97 fps with a bitrate of +/- 58.000 kbps.
The final video is 4K 29,97 fps as well, and I tried different bitrates (11,000 and 185,000), as I had to solve another quality issue in my edit.
I've tried exporting in x264 and Voukouder MOV, but it's all stuttering.

Attached you will find a part of the final video I'm editing with the stuttering.

I have no idea why there is stuttering in the final edit. Is there anyone that can help me out?

Would be much appreciated
Many thanks in advance!

Melle

Frame rate : 23.976 (24000/1001) FPS

The one you uploaded is 23.976 . If you shot at 29.97 , you probably dropped frames to achieve 23.976 . Try exporting it at 29.97 and keeping all the same settings at 29.97

The other way if you actually wanted 23.976 is to interpret the footage as 23.976 . That basically slows it down without frame drops to 23.976, so the duration is longer

[jagabo]

Yes, every 4th frame was deleted to convert 29.97 fps to 23.976 fps.

[MelleBax]

Sorry guys, I uploaded the wrong file.

The final edit is 29,97 fps as well (instead of the 23,97 in the wrong file).

Could there be another issue causing the stuttering?

If you want I can upload the final edit but the internet here is very slow

[davexnet]

Have you stepped through it frame by frame to see if you can spot a duplicate or obvious dropped frame?

[JVRaines]

What is your editing software? Encoding software?

[MelleBax]

Have you stepped through it frame by frame to see if you can spot a duplicate or obvious dropped frame?

I have not, but I will do so tomorrow (it's late here). Keep you posted!

[MelleBax]

What is your editing software? Encoding software?

I do everything with Adobe Premiere Pro. I exported in both x264 and Voukouder MOV 4K with same fps as original files

[johnmeyer]

Play the video in Premiere one frame at a time, but fairly rapidly so you can still get a sense of the time interval between frames. Try to sense of frames have been dropped (usually pretty easy to see if someone is walking across the frame). If you have dropped frames (like accidentally rendering at a different frame rate), then you need to fix that.

A more likely cause is that you have rendered using uncompressed or some other method that results in really huge files. This can strain some disk drive systems, and the video will drop frames during playback in an attempt to keep up, or it will simply wait until the next frame is ready. Either way you end up with video that isn't smooth. You can also get this problem if you render using a Profile setting (for h.264, for instance) that is higher than your playback processor can handle.

[MelleBax]

I checked it frame by frame but didn't find a duplicate or anything else that seems off.
I attached the complete file down the post, feel free to have a look.

It's especially the following shots:
00:46 - 00:53
00:53 - 00:57
00:57 - 01:01

If you compare it to the shot in 01:01 - 01:07 (which is super smooth and doesn't have any stuttering), you know something seems off with those 3 shots.

By the way, please don't mind the grain troughout the edit. I exported with relatively low bitrate and will export the final file with a higher bitrate that should solve this grain

Here is the full file: https://files.videohelp.com/u/275619/Beautiful%20Bali%20TEST.mp4

[jagabo]

00:46 - 00:53
00:53 - 00:57
00:57 - 01:01

Every 6th frame is missing in those shots. I didn't look closely at all the other shots but the few I checked had no missing frames -- and hence played more smoothly.

Also, the video is encoded variable frame rate. Did you have a mix of sources with different frame rates?

[MelleBax]

@jagabo, thanks for checking the footage.

How did you manage to find out that every 6th frame is missing?

I rechecked, and 3 shots are all shot with 29,97 fps, exactly the same as the output of the final video. Everything was shot on the same drone and as far as I can remember I didn't make any changes in settings in between.

Would it make a difference if I check the frame rates of every single shot in this video in my original folders?

I'm sorry for the many questions, I'm still new to making videos

[jagabo]

How did you manage to find out that every 6th frame is missing?

I stepped through the video frame by frame in an editor. You can see an extra large motion after every fifth frame. Obviously, a missing frame causes that extra large motion.

I rechecked, and 3 shots are all shot with 29,97 fps, exactly the same as the output of the final video. Everything was shot on the same drone and as far as I can remember I didn't make any changes in settings in between.

Did you speed the shot up? The most common method of speeding up video is to discard frames. For example, to make a shot run twice as fast you discard every other frame.

[MelleBax]

How did you manage to find out that every 6th frame is missing?

I stepped through the video frame by frame in an editor. You can see an extra large motion after every fifth frame. Obviously, a missing frame causes that extra large motion.

I rechecked, and 3 shots are all shot with 29,97 fps, exactly the same as the output of the final video. Everything was shot on the same drone and as far as I can remember I didn't make any changes in settings in between.

Did you speed the shot up? The most common method of speeding up video is to discard frames. For example, to make a shot run twice as fast you discard every other frame.

Yes I did speed up some shots

Those 3 shots I sped up to 120%, and some other shots anywhere between 120% up to 170%.

Would that be a potential cause of the missing frames?

[jagabo]

Yes I did speed up some shots

Those 3 shots I sped up to 120%, and some other shots anywhere between 120% up to 170%.

Would that be a potential cause of the missing frames?

That's the cause.

[MelleBax]

Yes I did speed up some shots

Those 3 shots I sped up to 120%, and some other shots anywhere between 120% up to 170%.

Would that be a potential cause of the missing frames?

That's the cause.

Thanks for the help Jagabo!
Is there any way to speed up the footage without messing with the frame rate of the shot?

If not, I'll try to get it back to 100% and see if it's better that way

[jagabo]

There are techniques that speed/slow video by analyzing motion between frames to generate new frames with in-between motions. Those techniques work especially well with panning shots. Look for optical flow, or motion compensation, options.

https://adobemasters.net/how-to-create-slow-motion-adobe-premiere/

You're going faster, not slower, but the same techniques apply.

[johnmeyer]

To add to what jagabo has said, any speed change (faster or slower) that is not an integral multiple of the original speed will leave you with an irregular pattern of either duplicated or dropped frames. This will usually be noticeable. So, if you speed up by 100% (i.e., 2x original speed), you drop every other frame, and the resulting motion is smooth because the time interval between each frame is the same. However, if you speed up by 20%, as you did, the time interval between each frame is not the same.

The optical flow (a.k.a. motion estimation) technique synthesizes new frames at the exact moment in time required to keep the time interval between each frame precisely the same. This avoids any jerkiness or jumps. However, it introduces the potential for optical flow artifacts. While the results of optical flow can often be near-perfect, when it fails, the failures are usually spectacular (meaning, they are awful), and are far worse than the jumpiness you get from changing speed the way you did.

You can also do speed changes by blending adjacent frames in order to get those intermediate frames that represent the exact moment in time needed to give you uniform motion. However, blending tends to make the video soft, with the worst softening happening when the new frame is exactly halfway in time between the two adjacent frames.

So, each technique has pluses and minuses. If you want to experiment, AVISynth has a plugin called MVTools2 that does motion estimation. Because it is pretty geeky, there are several front ends designed to make the technology more approachable. To get really good results, you have to tune the settings just right.

[jagabo]

Here's an example of optical flow with your video. On the left is a jerky segment from the video in post #10. On the right I used optical flow to restore the missing frames, then to speed up the video by 20 percent. You can see the motion is much smoother.

[MelleBax]

I have speeded up some clips to 200% and some I left in 100% speed and there is no more stuttering! Learned something again

Thanks everyone for all the help! I really appreciate it, this is an awesome community!