Converting VFR to CFR

Dexcon wrote on 7/21/2022, 9:02 AM

For many years, its been suggested that the best way to convert Variable Frame Rate (VFR) - typical of phone video - to Constant Frame Rate (CFR) is to transcode via a utility such as Handbrake. But very recently I've been converting VFR phone footage to CFR within Vegas Pro 19 itself - and it seems to work well. My Samsung phone records in mp4 VFR 23.97 (30) whereas I am in 25 fps land.

If I put a VFR phone video on VP19's timeline and R click to Properties, there is an option to hit "Confirm to Project Frame Rate" - 25 fps in my case. In both Properties and Project Properties, there is also the option in VP19 to choose the resample rate as Optical Flow. With all of these selected and then rendered, I get a smooth conversion from VFR 30 fps to CFR 25 fps (MediaInfo confirms CFR at 25 fps). The same video converted by Handbrake works but with stuttering - no stuttering via Vegas Pro 19.

I wonder if this works widely rather than having to go to a 3rd party app.

Comments

john_dennis wrote on 7/21/2022, 10:11 AM

I'm curious about the subject even though I've been successful avoiding VFR video. In order to do a scholarly test, "we" would need a set of source files with a wide range of frame rate variations. Then, we would have to test against the various hardware configurations in the wild. Since I don't use smart phones or do gaming with VFR monitors, I'm at a loss for producing such media.

wwaag wrote on 7/21/2022, 11:11 AM

The ImportAssist tool in HappyOtterScripts enables the user to change VFR to CFR with NO transcoding. It simply rewrites the Presentation Timestamps and as such it is very fast--plus no loss of quality due to transcoding.

Here's a demo of some iPhone 11 footage. https://vimeo.com/414271488/b80168621d

Change of frame rate using Optical Flow has always been a feature available in HOS but only recently added to Vegas. My suspicion is that Handbrake does not support OpticalFlow and explains the stuttering.

Former user wrote on 7/21/2022, 6:26 PM

If I put a VFR phone video on VP19's timeline and R click to Properties, there is an option to hit "Confirm to Project Frame Rate" - 25 fps in my case. In both Properties and Project Properties, there is also the option in VP19 to choose the resample rate as Optical Flow. With all of these selected and then rendered, I get a smooth conversion from VFR 30 fps to CFR 25 fps (MediaInfo confirms CFR at 25 fps). The same video converted by Handbrake works but with stuttering - no stuttering via Vegas Pro 19.

I wonder if this works widely rather than having to go to a 3rd party app.

This technique has been spoken about before, and I"ve showed it's failings. Optical flow on Vegas does not work correctly. (I may add the clip later), and you were just lucky with your video. I don't have the happy otter but I think it is the best way. You can be 100% assured you start whatever you're doing with all the frames available. With Vegas and VFR it is often the case it can't see all the frames, so in an optical flow example you are starting with a offset negative, Vegas has less data to work with.

Former user wrote on 7/21/2022, 6:42 PM

This is a similar thing, frame rate change, but not using VFR files. Optical flow works great in parts, but quality is not sustained

It is my hope it's fixed with VP20, they are bringing out new optical flow features

sakendrick wrote on 8/30/2022, 5:46 PM

Does anyone know what happened to VFR2CFR.zip from JN? Seems like he hasn't been in the forum since 2021 and link in his profile no longer works.

Former user wrote on 8/30/2022, 6:09 PM

@sakendrick I don't know what that is, the most recent discussion involved mp4fpsmod for VFR to CFR, which is here http://www.mediafire.com/file/qyrj0d84gfauvdm/mp4fpsmod-0.26-Win64.7z/file

The command required also given, search forum or web in general