Say hello to FlowFrames Video Interpolator!
A major problem for serious video makers is that of intermixed frame rates.
Any set of videos made with a multiple of 25 frames per second (the UK Standard) will happily mix together. Typically they are 25 – 50 – 100 FPS.
Or, alternatively, any set of videos made with a multiple of 30 frames per second (a US Standard) will happily mix together. Typically they are 30 – 60 – 90 – 120 FPS.
But woe betide the poor video editor who is confronted with mixture of both US and UK standards.
Quite simply, they don’t mix. In the case of 25 and 30 frame per second footage, each 1/5th of a second has a different number of images to cope with:
Therefore, if the editing timeline is 25 fps, then mixing 30fps footage is rather like trying to put a pint into a half pint pot – it won’t all fit.
The US footage has 30 images per second, but each second of the UK timeline only has space for 25 of those images.
That means that in every second, 5 of those 30 frames will need to be be discarded. As shown on the right, every 1/5th of a second caters for just 5 frames, so that one US frame has no location and is discarded.
The eye might not always spot it, but the reality of removing 5 frames every second is that the video with show some level of jerkiness. This will almost always be most apparent when watching a panning shot.
Although some editing software tries to compensate for it, perhaps by doubling up some of the extra frames, the fact is that is that it doesn’t fix it, it simply tries its best to mask it. The error will always be present.
The best way to ‘fix’ it currently is to slow down the 30 footage so that it closely matches 25 frames per second, and the eye can’t see any stutter. The formula to slow it down is to divide the frame rate (25) by the higher frame rate video (30). ie 5/6 or by 0.833 – not the easiest number to work with – but it does the job. Running the video at 5/6ths normal speed fixes the extra frame issue, plus it looks great for smooth and dreamy shots such as for wedding videos! But running the video slower might not be what is required.
Assuming that the poor editor has been confronted with some 60 fps footage (with no chance of a reshoot), and they are using a 50 fps timeline, they had two options:
1.Slow the 60 fps footage down by 0.833 of its normal speed so that it matches native 50 fps as previously mentioned,
2. Simply drop the 60 fps footage on the timeline and hope for the best (letting the editing software remove or juggle the extra 10 frames every second),
But now there is a third option – something that has only recently become available;
3. Utilise an Ai solution such as FlowframesVideo Interpolator.
https://nmkd.itch.io/flowframes
This program takes a series of adjacent frames and creates extra frames between them so that the overall number of frames per second is increased. For example, with 60 fps footage it can increase the number of frames by a factor of between x2 to x10. These interpolated frames are entirely generated using Ai so that the quality is good and the video motion becomes very smooth.
The next bit is the simple maths. The lowest common frame rate that both 50 and 60 frames per second can happily work together with is 300 fps. (Their multiples are 6 and 5 respectively).
In our case, using x5 with Flowframes will change our 60 fps footage to 300 fps by interpolating the extra frames needed and creating the new images.
This means that both the 50 fps and the 300 fps footage can now be placed together on the same 50 fps timeline without any issue. The playback is then as smooth as could be achieved natively, without stutters or jerkiness.
Brian O’Connell kindly provided some sample raw 60 fps iphone camera footage, and this video shows the three options the editor can choose.
The first clip in the video is slowed down to 5/6 ths (.833) normal speed making the video as close to native 50 fps as possible. The second clip shows the results of a typical editing suit – simply dropping the 10 excess frames every second (together with resultant jerkiness), and the third shows the results when using Flowframes to generate new extra frames to make a perfect 50fps match.
(Please bear in mind that you are watching this on YouTube and its extra processing will likely impact the quality)
This version of Flowframes does an exceptional job, and is free to run on your own PC (providing your hardware is powerful enough). At download they do ask for a donation but its your choice whether to offer something. There is a more advanced paid version, but for smaller tasks the free version should suffice.
Yet again, Ai lends a helping hand to video makers!
This smart software also has another use.
I am currently making a Pathfinders animated Pixar Style video, and I’ve used Flowframes to generate the extra frames so that existing footage can be slowed right down without any stuttering that might normally happen when a video drops below 25 frames per second.
But you’ll have to wait until July club night to see the results of that!
Jim