Question / Help OBS Crashed; file exists but won't play. Recoverable?

[Phnord Prephect]

So here's the deal...

I was recording a Pathfinder game on Roll20 when my display driver fritzed out on me, which caused OBS to close.
But then, in looking at my hard drive, I see the file exists; it has the appropriate bite-size (480meg) and everything, which means the data was in fact recorded. Which is nice. Because as you may or may not know, you can't just go back and re-do a Pathfinder game - all the magic is gone when you try (not literally of course.)

However, when I open the file, nothing plays. VLC player opens but does nothing; Windows media player gives the message that "The Player might not support the file type or might not support the codec that was used to compress the file."
Also, whereas the other videos in my folder have a "length" property, this one doesn't.

My assumption (yeah, I know what they say; just apply it to me, not yourself) is that the data was recorded but the OBS software didn't get the chance to finalize something-or-other. Whatever it needs to do to make the file playable, didn't happen.

So my question is, how can I make this file work? There should be a way to open it in OBS and 'finalize' it, I would think, but if so I can't find it.

Any advice?

 

[Harold]

You saved directly as mp4?
If so, that caused the problem and the file is completely unrecoverable.

Set your recording settings to save as flv instead.

 

[Phnord Prephect]

Well &#^@. Yes, I did save as .mp4. I was hoping there would be some way to recover the information.
Thanks for the reply, tho.

To clarify, you're saying that if I save as .flv, the file will be playable even after a catastrophic failure such as this in the future? I will implement that change immediately.

 

[FerretBomb]

Yes, FLV will only lose the last bit, and can be played post-crash. Quite a bit more robust than MP4. It really should be the default filetype in OBS (and IIRC was switched over to it in a recent patch, but that only addresses fresh installs). It's easy and fast to remux to MP4 if you need it later anyway.

MP4 keeps an 'atom' at the *end* of the file about the structure of the file and how to play it back. Without that, it's a big heap of digital trash. There are theoretical ways to recover it, but none of them work well, if at all. Closest I came with even a paid tool was a video that sped up and slowed down randomly, and the audio track sounded like a Chipmunks album. Oh, and couldn't be scrubbed through reliably. And some spots would crash VLC just trying to play it back. Not viable unless all I wanted was a couple of screenshots from whatever could be read. Best not to bother even trying, honestly.

In addition, extremely large MP4 files (7+ hours) take a long time to close out, can cause high-CPU issues even when just streaming, and actually increase the chances that OBS will crash while trying to close the video... and turn the recording into digital garbage.

tl;dr: USE FLV, NOT MP4.