Video lagging and bad quality after rendering

[PuccioTosch]

Hi there! I'm facing a terrible problem. I'm using Premiere Pro 2018. After rendering my video and producing it, I noticed it's not fluent at all and the quality is bad. I've never faced this problem. My original source video is 848x480 and I want to export it to 1920x1086. My video contains clip having different frame rates: some of them run on 43fps, instead most of them on 29.97 fps. I think the problem is in the slow-motion clips (43fps). I'm trying to change some options while exporting small parts of my video, but it still takes a lot of time (I can't spend 5 minutes for every attempt!). I've tried to find the solution online, but nothing seems working. I'm trying to export the video in 29.97fps, 50fps, 60fps but nothing changes. Moreover, the quality is low in all the cases, despite I export it in H.264. Moreover, I have some clips slowed using optical flow, so when I export the video, should I use optical flow or frame sampling (most of the clips use this last one)? It's driving me mad!

[Steve Griffiths]

Have your render settings for your H.264 encode changed? For example in the export dialogue menu try setting the 'preset' menu to 'Match Source - High Bitrate' (see attached image).

Additionally you are scaling your 848x480 footage to HD resolution - so you will see a significant 'softening' of your image in the HD output.

If you've already applied optical flow to clips in your sequence - no need to apply again in your export settings. Leave 'Time Interpolation' in your export setting at 'Frame sampling'

Also you mention 'not fluent', does this mean your motion is not appearing to be smooth in your exported videos? If so you should apply 'optical flow' to (most) clips in your sequence that do not match your sequence frame rate.

For example if your sequence is set to 29.97fps you should apply optical flow to your clips that do not match 29.97fps (like your 43fps clips).

However (another issue), and this might be what you are seeing - optical flow can create weird motion effects. They often appear as foregound movement appearing to drag' some of the background as the object moves. If this is a problem select 'frame blending' for these clips in your sequence.

Another option for clips that do not match your sequence frame rate is to right click these clips in your bin, select > modify > interpret footage and change the frame rate for the clips to match your sequence frame rate. Look for the 'assume this frame rate' section of the interpret footage panel. This won't work if your clips have sync sound, like people talking and in the case of changing 43fps footage to 29.97 will slow you footage down. 

Sorry, covered a lot. Hope this helps a little bit.

[PuccioTosch]

Should I export in 43fps or 29,97fps? 

[Steve Griffiths]

You should export at the frame rate your sequence is set at.

Generally most projects people work with have footage at all the same frame rate ... but in your case, having multiple frame rate source material I would suggest setting you sequence frame rate to match what most of your footage is.

So if you have mostly 29.97fps footage - then that would be your sequence frame rate.

Or 50 or 60 if that is what most of your footage is.

But not 43fps.

43 is a very odd frame rate!  - where is this footage coming from as it a very non-standard frame rate?

[PuccioTosch]

OK, so I should check the sequence settings.
I don't know why 43. I recorded 2 slow motions with an iPhone 8, but they have 2 different frame rates.

[PuccioTosch]

Moreover, if I use Match Source - High bitrate I don't get the HD option on Youtube because the video rendered is 848x480

[Steve Griffiths]

848x480 is a standard definition resolution. It's not HD. So putting this footage into an HD sequence (1920x1080) or exporting it to HD (1920x1080) is not going to make it HD.

There may be 'some' benefits to upscaling your 848x480 footage into an HD sequence if you are (say) adding graphics/text etc. but without knowing more about what you are creating it's hard to make the best suggestion.

But the bottom line is - yes you could put your 848x480 footage into a 1920x1080 sequence and scale it up to fit the HD frame - then export to a 1920x1080 video - so you can get the 'HD' option on YouTube but the video will still only have the resolution of a standard definition video. 

Does that make sense?

[PuccioTosch]

So there is no difference in quality if I my video is 848x480 or 1920x1080, cause my clips are all 848x480. Am I right?

[Steve Griffiths]

Quality will be best if you stay at the native resolution of your original footage (848x480). 

[PuccioTosch]

I've just noticed that one clip has 55fps. So should I export to 50fps or 60fps? Is there really a so big difference?

[Steve Griffiths]

You have a lot of non-standard frame rates in your project. Do you know why that is?

[PuccioTosch]

The non-standard frame rates come from the slow motion clips I made with an iPhone 8.

Well, I changed all the clips to optical flow, but the result is quite strange.There are some problems as the ones described by yourself. I changed the frame rate of the setting to 29,97fps and now it looks better

[Ann Bens]

All your footage looks like it has variable framerate.

Hence being a mess after export.

Make sure all footage has constant framerate (Handbrake).

Upscaling SD to HD nearly always results in image quality loss