Unable to get an avisynth recode to stay in sync

[pooksahib]

Hi. I've found a site with downloadable files of a favourite show of mine from the past - Bo Selecta. Here's the site if you're interested:
hxxps://archive.org/details/bo-selecta/Season+1/
I've taken episode one (which is mp4 and plays perfectly) and ran a script with LSMASH - audio out of sync. Tried again with ffms - still out of sync. I ran the mp4 through mkvtoolnix and used avisynth on the resulting file - out of sync.

Any idea as to why what seems to be a good mp4 file won't recode properly? And does anyone have any suggestions as to what else I can try to get an in-sync avisynth recode?

My thanks in advance.

[Selur]

MediaInfo reports:

Frame rate mode                          : Variable
Frame rate                               : 24.900 FPS
Minimum frame rate                       : 0.200 FPS
Maximum frame rate                       : 25.000 FPS

-> your source is vfr and you didn't handle the time codes. Either adjust the video to cfr or extract the time codes and add them back.
In case you, do the later make sure to edit them if you change length or speed of the file.

Cu Selur

[pooksahib]

Dank, Selur. Almost bedtime for me so I'll have to do some research tomorrow. I don't know how to 'adjust' the video to cfr (sounds simple though) and I certainly have no clue about extracting/editing time codes...

[davexnet]

To force the decoder to supply constant frame rate, something like this will do it:

FFVideoSource("C:\Users\davex\Desktop\Bo' Selecta S01E01 WEB-DL H264 BONE.mp4", track=-1, fpsnum=25, fpsden=1, colorspace="YV12", seekmode=0)

[pooksahib]

Thank you so much, davexnet - that worked perfectly. Although:
I omitted the colorspace and seekmode commands (my script didn't have a 'named argument' so MeGUI informed me).
I omitted the track=-1 command as MeGUI was adamant there were 2 tracks.

But, as I said, my shortened command worked. Out of interest, what would be needed for MeGUI to be happy with your full command?

When it comes to choosing the fpsnum is it just a case of picking the nearest round number i.e. if mediainfo says '24.9 variable' then make it cfr25?

Thanks again.