Salvage MP4 file with artifacts and heavy discolouration

[Monoploid]

Hey there,

I'm new at the forum and have a huge Problem with a video I recorded. Its a 1 hour 22 minutes Video recording made with OBS and directly saved to MP4. The only change I made from previous recordings that didn't cause this problems, is that I reduced the bitrate in OBS from 35mbits/s to 15mbits/s for space reasons.

I added some snippets for you to see what the problem is:

https://youtu.be/7NdNX1S9CA8

The video immediately starts out with some moving artefacts. This could still be tolerated but as the timeline moves on the artifacts get more and more intense, turning the whole video into a pink coloured, blocky mess. When skipping back and forwards in VLC player to the same point in time the artefacts look different every time. This leads me to believe there is still hope to save this footage as It doesn't seem "burned into" the actual video information. (Sorry for my nooby terminology). I tried different players and loaded the footage into Premiere Pro for editing - the problem persists across all platforms (Mac & PC, Premiere Pro, DaVinci Resolve, VLC, Quicktime)

I had the issue once before with a MKV file and was able to fix it by converting to MP4 via Handbrake. This doesn't work this time. In my desperation I even tried converting to MKV and back to MP4. Also no luck there.

Here the file infos pulled from Invisor:

File
Name: 2021-07-17 23-33-34.mp4
Size: 9.49 GB (9490026601 bytes)
Kind: MPEG-4 movie
UTI: public.mpeg-4
Location: /Users/robinbarth/Movies
Created: 17. July 2021 at 23:33:35
Modified: 18. July 2021 at 00:56:08
Container
Format: MPEG-4
Format profile: Base Media
Codec ID: isom (isom/iso2/avc1/mp41)
Duration: 1 h 22 min 30 s 0 ms
Overall bit rate mode: Variable
Overall bit rate: 15.3 Mb/s
Writing application: Lavf58.29.100
Video
ID: 1
Format: AVC
Format/Info: Advanced Video Codec
Format profile: Main@L4.2
Format settings: CABAC / 2 Ref Frames
Format settings, CABAC: Yes
Format settings, Reference frames: 2 frames
Codec ID: avc1
Codec ID/Info: Advanced Video Coding
Duration: 1 h 22 min 30 s 0 ms
Bit rate mode: Variable
Bit rate: 15.0 Mb/s
Maximum bit rate: 768 kb/s
Width: 1 920 pixels
Height: 1 080 pixels
Pixel aspect ratio: 1.000
Display aspect ratio: 16:9
Frame rate mode: Constant
Frame rate: 60.000 FPS
Frame count: 297000
Color space: YUV
Chroma subsampling: 4:2:0
Bit depth: 8 bits
Scan type: Progressive
Bits/(Pixel*Frame): 0.121
Stream size: 9.28 GB (97.8%)
Color range: Limited
Color primaries: BT.709
Transfer characteristics: BT.709
Matrix coefficients: BT.709
Codec configuration box: avcC
Audio
ID: 2
Format: AAC LC
Format/Info: Advanced Audio Codec Low Complexity
Codec ID: mp4a-40-2
Duration: 1 h 22 min 29 s 952 ms
Bit rate mode: Constant
Bit rate: 320 kb/s
Channel(s): 2 channels
Channel layout: L R
Sampling rate: 48.0 kHz
Frame rate: 46.875 FPS (1024 SPF)
Frame count: 232030
Compression mode: Lossy
Stream size: 198 MB (2.1%)
Title: Track1
Default: Yes
Alternate group: 1


Unfortunately I'm not able to re-record the session as we had guests from abroad so I'm running into huge trouble when I can't get this fixed.

With MP4 being a compressed format is there any chance to salvage the footage?

Thank you in advance.

Rob

[davexnet]

Cut a representative 30 second sample direct from the source. No re-encoding. Post it here

[Monoploid]

Cut a representative 30 second sample direct from the source. No re-encoding. Post it here

Thanks for your reply. Can you advise me how to cut without from the source without reencoding?

[davexnet]

Avidemux

[Monoploid]

Avidemux

Thank you! Here you go: https://files.videohelp.com/u/300030/Artifacts_cut.mp4

Looking forward to hear your opinion.

[Monoploid]

P.S. Sorry for sending almost 3 minutes, Avidemux wouldn't let me set the marker at the point I wanted. No idea if that's because of the program or a problem with the file itself.

[jagabo]

I don't think there's any way to fix that clip. Consider it an exercise in datamoshing. But...

The entire clip is a single GOP -- over 10000 frames And there's no telling how much longer the GOP was before you cut it. Next time use shorter GOPs (I frame interval), no longer than 1 or 2 seconds (60 to 120 frames at 60 fps). That way your corruption will be limited to 1 or 2 second sections. And the video will be much more playable/editable.

Also, there are many many duplicate frames in an irregular pattern. The system wasn't able to capture 1080p at 60 fps properly -- at least with the settings you used.

[Monoploid]

Hi jagabo, thanks for your reply.

That's bad news... I will consider your advice for future recordings though.

If it was just the "datamoshing" artifacts at the beginning, it would be kinda cool but as it becomes fully overexposed and blown out later in the video it makes it pretty useless.

I guess there's nothing I can do to even reduce the discolouration (except for color correction in post) ?

Thank you guys !

[jagabo]

By the way, in AviDemux you can move to the next I frame with the up arrow on the keyboard, previous I frame with the down arrow. That will let you see what your GOP size is.