Transplanting audio track from 25fps movie to 23,976

[Ygramul]

I have two video files:
- Movie A (low quality 25fps video, English audio) CLICK FOR MEDIAINF0 FILE
- Movie B (good quality 23,976fps video, Hungarian dub) CLICK FOR MEDIAINF0 FILE

I want to remux them to create movie C (audio from A, video from B). I tried a few methods and the output is always out of sync.

- TFMAudioTool (enable framerate conversion - PAL to NTSC, output format: MP3 CBR 320kbps)
- Clever FFmpeg GUI (25 -> 23,976 fps, length + pitch, 48000Hz, AAC)

Then I use Reaper to import both the output AND Movie B so I can line up both audio tracks. I do this to avoid manually adjusting a/v sync while watching the movie. They both line up perfectly (both start and end). Then I render the readjusted track as 320kbps MP3 again (sigh).

Finally I use Avidemux to replace the track from Movie B with the track rendered with Reaper.

What else can I do?

[johns0]

Most likely the videos have different scene changes/length and that will cause sync issues,what you need to do is check the first part of the videos to see if they match and and if the scenes are different when going to the next part,if there's new additions to the video then it's not worth doing,if its the same video after the scene and the lengths are different then you need to edit all the scene changes so they match.

[davexnet]

Yes, you can use something like stackhorizontal in Avisynth to put them up at the same time to see if they match

[Ygramul]

Most likely the videos have different scene changes/length and that will cause sync issues,what you need to do is check the first part of the videos to see if they match and and if the scenes are different when going to the next part,if there's new additions to the video then it's not worth doing,if its the same video after the scene and the lengths are different then you need to edit all the scene changes so they match.

This is a fair point. I got so fixated on the technical aspect of this endeavour that I forgot how often movies get censored (cut 1 second here, cut 4 seconds there). You're right, it probably isn't worth my time.

I have another question, though. What exactly is SPF? I took a look at a few random movies I have and the FPS/SPF value in Mediainfo varies a lot:

23,976		31.250 FPS (1536 SPF)		AC3
23,976		38.281 FPS (1152 SPF)		MP3
23,976		43.066 FPS (1024 SPF)		AAC
25		46.875 FPS (1024 SPF)		AAC
25		31.250 FPS (1536 SPF)		AC3

[ProWo]

I have another question, though. What exactly is SPF?

SFP means sample per frame, it's audio related.
Example:

Frame rate: 93.750 FPS (512 spf)
93.750 audio frames per second * 512 samples per frame = 48000 samples per second = 48 kHz sampling rate

[Ygramul]

I have another question, though. What exactly is SPF?

SFP means sample per frame, it's audio related.
Example:

Frame rate: 93.750 FPS (512 spf)
93.750 audio frames per second * 512 samples per frame = 48000 samples per second = 48 kHz sampling rate

All right, but does it have anything to do with a/v sync? Why do all those movies have varying SPF and FPS?

[johns0]

Nothing to do with sync,just different codecs with different bitrates.

[Ygramul]

I took a closer look at one of the problematic movies and the framerate had a lot of anomalies. Some frames would get up to 5 duplicates. It all makes sense now.