Recoding low Framerate to higher Framerate

glenpinn

Member
Hi everyone, i am curious to know what are the Pro's (if any) and Cons for recoding files at a higher framerate to what they were shot in.

I am only asking because i see so many 1080p and 4k videos that were shot using low framerates such as 24fps, 25fps, 29.970fps and 30fps and it does my head in watching many of these files because my eyes are very sensitive to jittering and jerkiness, especially in panning scenes and where there are objects moving fast past the camera, such as cars and people walking, and i often see sports videos also shot in lower framerates when they should be shot at a higher framerate to avoid this jerkiness, and car racing videos would be one classic example where video needs to be shot using a high framerate.

I have always shot video at 50 or 60 fps for this reason, as i love my videos to look smooth and not have any of this horrible jerkiness going on, but many people don't believe that video should be smooth, and reckons that anything over 25 or 30 fps is criminal.

Scenario 1: a video file shot in 1080p @ 29.970 fps, if i recode this file at a higher frame rate, should it be doubled to 59.940, or can i do it at 50 or 60 fps (i have already done several of these to 50fps and they seem to play back fine)

Scenario 2: a video file shot in 4k @ 25fps, if i recode this file at a higher frame rate, should it be doubled to 50 fps.

Any thoughts much appreciated.
 

glenpinn

Member
I also need to ask if it is possible, or wise, to join multiple files together which have the same resolution but different framerates and bitrates.

I had 3 different 1080p files that i wanted to join together to see how it played, one was 29.970fps, one was 50fps, and another was 59.940fps.

I chose to join them and output them at 50fps, but these 3 files would not load into the VRD joiner list because of the different framerates, so i decided to recode the 29.970 and the 59.940 files to 50fps individually to match the other 50fps file.

When those 2 files were recoded at 50fps, i imported all 3 files into the joiner list, and i joined them together successfully, and the joined file seemed to play back ok.

I asked this question in the Handbrake forum, and i was given the 2 following replies.

1. Handbrake will drop or dupe frames to match your chosen frame rate. Not always the best result.
A nonlinear editor with temporal field processing is the way to smooth motion.

2. The best option is to output variable framerate video.


Is there any way, or would it even be possible for VRD Pro to import multiple files with the same resolution but with different framerates into the Joiner List to save having to recode each file to the required framerate first, and then join them.

Cheers
 

Dan203

Ex-Senior Developer
There is no benefit to increasing the frame rate unless you need to for compatibility with some playback device or disc format. In most cases it will actually make it worse as you'll increase the number of frames in the video either increasing the size or reducing the average number of bits used to encode each frame.

Basically unless you have a specific reason to increase the frame rate you should avoid it.
 

glenpinn

Member
I understand what you are saying Dan, i don't normally need to do this, however i do have 2 clients who bring me files of differing framerates that need to be joined.

I am lucky here because his source files will be either 29.97 or 59.94 fps, so i only need to double the 29.97 file to match the other 59.94 files, and it seems to work very well.

At least you guys at VRD have implemented this feature of doubling the framerate without the output file being jerky, unlike in Handbrake and many other editing tools, and i have made those in the Handbrake forum aware of this issue, and they are looking into it, but they seem to have conceded that there is an issue somewhere in their software that causes the output file to be jerky, and not a bit jerky, it is actually very jerky.
 

Dan203

Ex-Senior Developer
In VideoReDo when the frame rate is exactly double we simply duplicate every frame. So it's basically just like displaying each frame twice as long, which is exactly what your TV will do to match it's refresh rate. I have no idea how Handbrake does it.
 

glenpinn

Member
Well i did an output of a 1080 file from 29.97fps to 59.94fps in Handbrake and it was severely jerky, i sent the Log file to one of the developers of Handbrake and even he was surprised at the outcome, but had a suspicion as to what may be happening.

I posted the exact same output file done ising VRD into their forum and some downloaded it, and they seemed quite surprised at how well it looked on playback.

So although i don't usually double framerates, at least i know that yet again, VRD is able to do the job that others can't seem to do.

Oh, btw Dan, i will be contacting you guys regarding the Title tool in the Joiner list, it is not working again with my current 818g build.
 

glenpinn

Member
Unfortunately with VRD there is no Double Framerate option in any of the profiles, probably because nobody would actually use it, and that would seem logical for most people, if you shoot at a given framerate why would you then double it.

For me, i never shoot video at lower than 50/60fps, as i do a lot of Run-n-Gun type video where i am walking around and panning while filming stuff such as travel videos etc, so i need my videos at least 50 or 60fps to prevent any kind of jerkiness from happening.

My issue has more to do with watching other peoples videos that were recorded at 30fps or less, not so much in scenes where there is not a lot of panning or fast movement going on, my problem is when there is panning of the camera and/or there is a lot of fast movements happening in the scene being recorded, things such as people walking or running, vehicles driving past the camera etc etc etc, as this sort of stuff causes some degree of jerkiness in the playback, and my eyes are very sensitive to this and can make watching this sort of video very difficult for me.

So when i get lower framerate videos from people where i can notice any kind of jerkiness going on, then i will recode it by doubling the framerate IF i can, unfortunately i am restricted to videos recorded at either 25 or 29.97 or 30 fps as i can simply select 50 or 59.94 or 60 fps in the output profile framerate list, BUT if i have a video recorded at 23.976 or 24 fps and i see jerkiness going on, then i cannot double the framerate using VRD as there is no option for 48 or 47.952 fps inb the framerate options list.

Maybe if either of the Dans read this Topic then they might like to look into the possibility of including a "Double Framerate" option in the profiles list, but for me i am not that bothered, as most of the videos that i have had to double the framerate have been either 25 or 29.97 or 30 fps anyway.

I should note here that i have used several other Encoding programs, including Handbrake to double the Framerate of a video file, and all of them fail to do it properly, Handbrake especially causes the output video to jerk even more than the original file did, where as VRD seems to double the framerate and it does manage to decrease any jerkiness that was in the original file, and this is yet another reason why i absolutely love using VRD.
 
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