ChangeFPS or ConvertFPS?

[agni451]

I know there are some threads out there about this subject, but they all seem to address PAL --> NTSC. I want to go from NTSC 29.97fps to 23.976fps so that I can get more quality per frame for the same bitrate. Do I use ConvertFPS or ChangeFPS? Since ChangeFPS will drop frames, I'm guessing that could make things a little choppy. But ConvertFPS will blend frames.

I'm using x264 command line with avisynth, after frameserving with DGIndex (NOT DGIndexNV). The source file is a 59.94fps 720p .ts video clip that I've already added "SelectEven()" to in the avisynth script.

[poisondeathray]

I know there are some threads out there about this subject, but they all seem to address PAL --> NTSC. I want to go from NTSC 29.97fps to 23.976fps so that I can get more quality per frame for the same bitrate. Do I use ConvertFPS or ChangeFPS? Since ChangeFPS will drop frames, I'm guessing that could make things a little choppy. But ConvertFPS will blend frames.

I'm using x264 command line with avisynth, after frameserving with DGIndex (NOT DGIndexNV). The source file is a 59.94fps 720p .ts video clip that I've already added "SelectEven()" to in the avisynth script.

Not a good reason to do a framerate change. The jerkiness isn't worth it

You can use motion interpolated frames using svpflow or mvtools2 based functions - everything will be smoother because frames will be evenly spaced in time (what happens is you interpolate every 2nd frame from 60p => 120p then divide by 5 to get 24p). But they have problems as well , some content is poorly interpolated you have edge morphing artifacts.

I would leave it as is, or SelectEven/Odd for 30p

[jagabo]

If your source is film based, inverse telecine back to 23.976 fps. TFM().TDecimate().

[zagnut]

There's a couple ways you can do this actually. (I'm in the process of testing for some of my footage).

Assuming your 60fps footage is interlaced -

Deinterlace 60i to 30p. Use ChangeFPS to convert 30p to 60p. Use AssumeFPS and slow 60p down to 48p. Then use ChangeFPS to convert to 24p, deleting every second frame.

Deinterlace 60i to 30p. Use ChangeFPS to convert 30p to 120p. Then use ChangeFPS to convert to 24p.

Deinterlace to 30p. Use AssumeFPS to slow footage down by 25% to get 24p.

Final way is to resample footage. Here's how in Adobe After Effects -
If dealing with 60i, deinterlace to 30p first and convert to 60p using ChangeFPS. Drag and drop your 60P clip onto the Make New Composition icon. After the comp is created, go to the comp's settings and change the frame rate form 59.94 to 23.976. In the timeline, turn on Frame Blending (choose pixel motion, not frame mix) for the clip and set it's quality to high (that's the solid diagonal black line). That's it. Render, and you'll have a 24P version of your movie. This particular method is supposed to work extremely well from what I've read.

Of course, if your footage is already 60p, and not 60i, you can skip deinterlacing and converting to 60p. Good luck.

[Gavino]

Deinterlace 60i to 30p. Use ChangeFPS to convert 30p to 60p. Use AssumeFPS and slow 60p down to 48p. Then use ChangeFPS to convert to 24p, deleting every second frame.

That's useless.
Since the first ChangeFPS duplicates each frame, and the second one then deletes every second frame, together they achieve exactly nothing. The overall effect is to deinterlace to 30p and then (because of AssumeFPS) play it back at 24p. The 20% slowdown will be obviously visible, as well as putting the audio out of sync.

Deinterlace 60i to 30p. Use ChangeFPS to convert 30p to 120p. Then use ChangeFPS to convert to 24p.

There's no need to call ChangeFPS twice - going directly to 24p in a single call will give exactly the same result.

Deinterlace to 30p. Use AssumeFPS to slow footage down by 25% to get 24p.

(Don't you mean slow down by 20%?)
This has the same effect (and unwanted consequences) as the first 'solution' above.

A better solution than all the above is to (bob) deinterlace to 60p, then use ChangeFPS to get 24p.
But like pdr, I'm not convinced you should be doing the conversion at all.

[jagabo]

You can use motion interpolated frames using svpflow or mvtools2 based functions

Here's an example: https://forum.videohelp.com/threads/345077-30fps-24fps-WITHOUT-pulldown?p=2152668&viewf...=1#post2152668 Interlaced video will have to be deinterlaced first.