Question / Help Question about mp4 recording

[BobbyGoogus]

Hey everyone,

So about a month ago, I was recording a playthrough of a PC Game in segments, and during the 5th segment (each roughly an hour long), I went to end the recording and close OBS as usual, and it gave me some sort of message saying OBS was still encoding, would you like to wait? I clicked yes, but OBS closed anyways, and even though my video file size was roughly correct for the length/resolution of the footage, it couldn't be opened in ANY video player. I tried everything to recover it, but nothing worked. After some googling, I saw that this had happened to a few other people over the course of time. I read that the reason this happens is because OBS puts the metadata for the mp4 at the very end of the recording, so if anything is dropped/lost while it's finishing, you might lose the file. Now this is a BIG problem for games that autosave your data, which was the case for this recording.
So, onto the question. I guess I'd more just like some general info on why this happens/how I can 100% avoid this issue (if possible). I read that this sort of thing is more bound to happen if your .mp4 recording goes on for longer than an hour, I'm not sure if that's true. I've switched to recording in .flv because I heard it's much more reliable, and the recordings can go on for as long as you want. The problem with this is that .flv is HUGE, and I have to then transcode all of the footage back into .mp4 because Premiere Pro doesn't like .flvs, which takes a really long time (and I just upgraded to an i7-4790K processor).
So, if anyone could just make me more knowledgeable as to why this happens with .mp4s, ways to avoid it, etc. that would be great. I've honestly been so scared of losing my footage since then that I haven't gone back to .mp4s, but it'd really help if I could.

 

[FerretBomb]

OBS isn't the only program that puts the metadata at the end of an MP4. That's required by the file format.

ANYTHING that records direct to MP4 will have the same problem.

Yes, longer files are more likely to be affected, as it takes longer to close them out (and are more likely to crash OBS as well). Recording to MP4 can also cause high CPU load problems during a recording, on longer videos.

Record to FLV, and remux to MP4 if you need it later. That's the only way to avoid this issue. To fast remux (which takes a minute or two at most) follow the fast-remux guide, or just use the 'remux' option in OBS Studio's File menu.
Fast-remux guide:
https://obsproject.com/forum/resources/how-to-convert-flvs-to-mp4-fast-without-re-encoding.78/

Recording to FLV is only marginally larger than MP4, and is significantly more robust; if you happen to crash, you'll only lose a few seconds from the end at most. It's just a different container format, which is also why it can be fast-remuxed over, no transcoding or re-encoding necessary (though something like Handbrake can improve recordings' filesizes significantly, given time to crunch down a re-encode with a higher quality or multi-pass non-realtime encoder).

 

[BobbyGoogus]

OBS isn't the only program that puts the metadata at the end of an MP4. That's required by the file format.

ANYTHING that records direct to MP4 will have the same problem.

Yes, longer files are more likely to be affected, as it takes longer to close them out (and are more likely to crash OBS as well). Recording to MP4 can also cause high CPU load problems during a recording, on longer videos.

Record to FLV, and remux to MP4 if you need it later. That's the only way to avoid this issue. To fast remux (which takes a minute or two at most) follow the fast-remux guide, or just use the 'remux' option in OBS Studio's File menu.
Fast-remux guide:
https://obsproject.com/forum/resources/how-to-convert-flvs-to-mp4-fast-without-re-encoding.78/

Recording to FLV is only marginally larger than MP4, and is significantly more robust; if you happen to crash, you'll only lose a few seconds from the end at most. It's just a different container format, which is also why it can be fast-remuxed over, no transcoding or re-encoding necessary (though something like Handbrake can improve recordings' filesizes significantly, given time to crunch down a re-encode with a higher quality or multi-pass non-realtime encoder).

Okay, great to know! One thing though- you say .flv is only marginally larger than mp4....my mp4 files (when roughly an hour long) were about 2-5 gigs, my .flvs however, with the same OBS settings, and roughly the same length, are about 20-25 gigs. Is this normal? I feel like it isn't right.