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  1. Member
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    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
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  2. Member
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    Cut a representative 30 second sample direct from the source. No re-encoding. Post it here
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  3. Member
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    Originally Posted by davexnet View Post
    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?
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  4. Member
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  5. Member
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    Originally Posted by davexnet View Post
    Avidemux
    Thank you! Here you go: https://files.videohelp.com/u/300030/Artifacts_cut.mp4

    Looking forward to hear your opinion.
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  6. Member
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    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.
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  7. 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.
    Last edited by jagabo; 20th Jul 2021 at 17:44.
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  8. Member
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    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 !
    Last edited by Monoploid; 20th Jul 2021 at 18:22.
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  9. 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.
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