Mp4Box is failing to merge files with one I encoded

[Cyber Akuma]

My camera is hard-coded to split files at the 4GB mark even if the filesystem on the SDcard I am using can handle files over 4GB.

Ok, fair enough, it's a few seconds of extra work but I can always use MP4BOX to just merge them. And normally this would work, but during one of my recordings I have a 10 second gap near the end. It looks horrible to just merge them like that with the cut, and re-encoding an hour long video just to add a quick transition in the last minute would normally not be worth it, but I lucked out in that it had just started a new file past the previous 4GB mark when the cut happened, so I just have to add a transition between a 15 second and 1 minute file.

I wrote a simple AviSynth script to add a transition and then tried to use MP4BOX to merge them, but now it's not working. MP4BOX does not seem to like the clip I encoded as it's finding something (I honestly have no idea what) incompatible with it, and fails to properly merge the video. It tosses the warning "No suitable destination track found - creating new one (type vide)" and spits out a file that will not play. This only occurs when I attempt to add the encoded file in the mix, it has no issues merging all the original untouched files.

I am not sure what kind of information I am even supposed to provide to try to help with this.

Here is my AviSynth script:

Mov1=FFmpegSource2("video1.mp4", atrack=-1)
Mov2=FFmpegSource2("video2.mp4", atrack=-1)

Eff1=TransRipple(Mov1,Mov2,24,20,8)

FullMov = Eff1

ConvertToYV12(FullMov)

And what data MPC-HC reports for one of the original files:
https://pastebin.com/KMwqpxFv


As well as what I encoded:
https://pastebin.com/ZpvZ3pSL


I honestly do not see any difference, so I have no idea what MP4BOX is complaining about.

Does anyone have any suggestions what I can look into that could be causing this issue with MP4BOX failing to merge the files?

[jagabo]

High@L4.2 vs. High@L5.1? Along with all the other settings that implies (too many reference frames, too many b-frames, etc.).

[Cyber Akuma]

I tried matching the settings in the x264 encoder in MeGui with those of the other MP4 file, however, despite manually setting reference frames to 2, it seems to refuse to go lower than 4, and I still get the same issue with MP4BOX with the new file. This is what the new file I encoded looks like:

https://pastebin.com/j3sCMmeE

[jagabo]

Try adding the x264 options

--profile high --level 4.2 --stitchable

Also, try appending with MkvToolnix. If that works, and the resulting file plays properly, demux with MkvExtract, then mux the elementary streams to mp4.

[Cyber Akuma]

The encoded file itself plays properly, I mean once I try to merge it with the others in mp4box is when the merged file does not play properly. This only happens if I attempt to add the file I encoded with the originals in the merge, if I just merge the originals I get no warnings and the output from mp4box plays fine.