[FFmpeg-user] Fwd: OBS and OBS Portable Recording Into Same File Simultaneously

[David Bayles]

Corrupted video file, FFprobe output text file, and FFmpeg output text file
are all available to download here:
https://drive.google.com/drive/folders/1R0Y5plgkhTWWFNNKgSNJ5yitpKQbIKgg?usp=sharing

I'm hoping there is a way to extract good video and audio from this video
file, this was for a very important job that is impossible to do again. The
video linked is a 1 minute recreation of the exact same problem... the
actual video file is confidential (for a legal court case) and is much
longer/larger. I used the exact same settings, the only difference was the
window OBS was capturing (I used a YouTube video as opposed to the
videoconference software window used for the deposition).

Here's what happened:

In OBS and OBS Portable, my video technician had the save location set to
the same exact folder (this was not how I intended it to be, but he made a
last minute change to accomadate what he suspected was a faulty hard
drive). We also had a hotkey to start recording on both apps
simultaneously. We left the auto naming scheme in place for both instances
of OBS since they were supposed to be saving to two totally different
external hard drives (we have since changed this). This perfect storm
resulted in both recordings being written into a single file (see link
above), instead of two files as intended. It is unplayabe in VLC.

I ran an FFprobe (available via link above), and found that there are 8
streams in the file. Each file should have had 4 streams (1 video and 3
audio streams per my setup in OBS), so at first glance it looks like all
the data is there in some form/arrangement.

I tried to map the 0:0 stream to a new file and tried the same thing with
the 0:4 stream (these are the video streams), but did not have any luck
extracting good video. Here are the two things I ran (again see link above
for text files with full FFmpeg ouput of each):

ffmpeg -i C:\Users\David\Videos\2020-06-23_17-39-32_corrupted.mkv -map 0:0
-c copy C:\Users\David\Videos\2020-06-23_17-39-32_corrupted_map0-0.mkv

ffmpeg -i C:\Users\David\Videos\2020-06-23_17-39-32_corrupted.mkv -map
0:4 -c copy C:\Users\David\Videos\2020-06-23_17-39-32_corrupted_map0-4.mkv

It seems the audio is intact, as I was able to map one of the audio streams
into a wav file... although there seemed to be extra/repeated audio tacked
onto where the video/audio should have ended...

It looks to me like both video streams got written into stream 0:0, while
stream 0:4 looks empty (because this map results in a very small file).
However the thing that's weird (and maybe promising) is that when I play
the corrupted file in VLC, it mostly looks like smeared digital colors, but
if I click around to different times in the video, it sometimes shows good
video.

My life would saved if there is a way to extract good video/audio from this
corrupted file. Any help would be greatly appreciated, thanks in advance!