Video capture frame rate vs. final output file frame rate

[Theodore]

Hello,
Newbie question here. I have converted 8mm film to digital using a Wolverine Movie Make Pro. It's output is a (1440x1080) mp4 at 20fps. After I import into my non-linear editing program, I need to change the speed of the output file because everything looks too fast as-is. The speed is currently defined as 100%, and I can only change as a percentage. Can anyone help explain this speed ratio problem and what percentage I should be setting this to so it looks ..."normal"?
Many, many thanks.
Theodore

[smrpix]

Which NLE are you using? Super 8 is normally 18fps, Regular 8 is 16fps.

[Theodore]

Hi, I'm using the free/open source Kdenlive, which seems to be behaving well/agreeable
Thank you for reminding me about the other film types. I will be converting 8mm AND super 8mm film on my Wolverine Movie Maker Pro. I understand that the output file of this machine, in each case, will be the same: (1440x1080) mp4 at 20fps. Any guidance you can offer is greatly appreciated.
Regards,
Theodore.

[jagabo]

Consumer 8mm film usually ran at 14 to 16 fps, super 8 around 18 fps. I believe the Wolverine produces one frame of video for each frame of film, and they mark it as 20 fps because that converts to 60 fps (for computer monitors and TVs) with 3:3 pulldown or repeats, delivering smoother motion. But if you want the original frame rate you'll have to slow the video down to the original film frame rate. Be careful, there are two ways programs perform slowdown, by increasing the time each frame is displayed (1/20 second to 1/18 second per frmae) or by adding frames (18 frames becomes 20 frames by duplicating every 9th frame). You want the former.

[Theodore]

Thank you for the reply. I think I understand what you're saying but, in practice, the attached image is what I am allowed to change (speed in percent), while acknowledging that the mp4 rate is 20fps. I would like to render these videos so they appear to play at a normal/human speed and not what appears to be too fast. Is there any way I can calculate what percent I should be entering?

[poisondeathray]

If you assume it was 16fps , 16/20 = 0.8 or 80%

In other editors , one approach is to interpret the frame rate of the asset. You do this before editing, usually in the clip bin. This changes the frame rate of the video, but keeps the same number of frames. So if you assume 16fps, it just plays back at 16fps. So if you edit on a 16fps timeline it's 1:1 perfect frames , nothing dropped or added

But right now I assume you're using a 20fps timeline. Chances are it's going to insert duplicate frames to make up 16fps in 20fps. The frames won't be evenly distributed, so playback will be less smooth

If you can't interpret the frame rate in kdenlive, another approach might be to "patch" the mp4 file to 16fps, such as using mp4box, before importing clips into the editor