Today we had to give a video presentation for the technically unannounced BCC Arte & Cultura project, and that involved a whole lot of Blender animation renders. One of them, a long one that took hours in Cycles, crashed at the very end. We were exporting in mp4 format, which is easy to import in video editors, but is quite hard to recover if the file is not terminated correctly.
VLC wouldn’t open it, and FFMPEG threw a “ERROR MOOV atom not found” warning, and then was unable to process any data.
With no time to spare for another render pass, we found this forum thread: https://www.videohelp.com/software/recover-mp4-to-h264
It’s a tiny and self-explanatory command-line utility, that saved us and gave us a usable file in seconds.
The only problem is that it’s Windows only.