How to compare different fps side by side

[Takie]

Hello forum members,

I would like to preview 2 videos side by side, one at 23.98 fps and another that has been frame interpolated to 59.94 fps. In the past I used this script for videos of the same frame rate:

result = ffvideoSource(...)
source = ffvideoSource(...)

source2 = crop(source,Width(result)/4,0,-Width(source)/4,0)
result2 = crop(result,Width(result)/4,0,-Width(result)/4,0)
STACKHORIZONTAL(source2,result2)

But when I do this on the aforementioned, the first one is played at normal speed while the interpolated clip gets slown down. Is there any way to make them play 'in sync' at the same time?

[Gavino]

StackHorizontal 'inherits' the frame rate of the first clip and the second clip is just shown frame-for-frame with the first.
If you want the two in sync, you will have to convert one of the clips to have the same rate as the other (eg using ChangeFPS or ConvertFPS)

[IanB]

Assuming your PC has enough grunt, ChangeFPS(120000, 1001) on each clip before you StackHorizontal.

This will then display 5 copies of each frame from the 23.98 fps clip synchronised to 2 copies from the 59.94 fps clip.

An alternative to ChangeFPS is SelectEvery(1, 0,0,0,0,0) and SelectEvery(1, 0,0) if the input fps's are not an exact N/1001 rate.