We can't investigate an issue with a sample file where there's no problem.
Please share a problematic sample file.
Thanks
If you have a way to move headers at start of file (fast start)
and then truncate after a few megabytes, that would still be a valid sample
Otherwise you can also zerofill inside the mdat section after few MB and compress the whole easily
I'm happy post a problematic file to Google drive for you to download.
The problem only happens with large files. If someone wants to step me the the process of filling a 150Gb file with zeros for compression, I'll do that but it's much easier for me to simply render a test and upload it.