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  1. Member
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    I am familiar with frame-accurate cutting operations for avc source (e.g., cutting on keyframes, open and closed gops, etc.), but I've never tried cutting 265 with HDR layers. I assume things work the same as 264 regarding the video stream (e.g., need to cut on closed gop boundaries), but I'm confused about the HDR metadata layers. Do those simply get sliced in place, too? What if some reencoding is necessary, do the HDR layers remain unaffected? Do HDR layers add any complexity or problems when trying to cut 265 files? I'm new to the whole 4k HDR scene.

    For 264 material, I usually use mkvmerge/mkvtoolnix because it is easier for me and handles the audio and subtitle tracks well. I'll do a little reencoding with ffmpeg if I need to place keyframes for cutting. Anyone see a problem with this approach if I tried it with 265 and HDR layers?

    Thanks in advance.
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  2. For static hdr data (hdr10) I see no problem. For dynamic meta data (hdr10+, dv), the reencoding for the frame accurate cutting would require to extrat the dynamic data, cutting the data and re-adding it to the reencoded cut stream.
    For dv extracting the hdr-meta-data, manually edit it and re-apply the meta data should be possible using https://github.com/quietvoid/dovi_tool.
    For hdr10+ extracting the hdr-meta-data, manually edit it and re-apply the meta data should be possible using https://github.com/quietvoid/hdr10plus_tool
    iirc both can convert the meta data to and from a human readable json format which addresses the frames by indices, so simply deleting the removed sections and apply the indices accordingly should work.
    (Note that I haven't done this myseld and this is only from what I read a while ago when I was curious about the same thing.)

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    That is exactly what I'm looking for Cu Selur, thank you! In regards to cutting the main video stream, do you think my normal route of mkvmerge and/or ffmpeg is appropriate, or is there another program that would be better? I run Windows.
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  4. They should both work fine while cutting on gop boundaries (without reencoding).
    In theory (assuming you only reencode and don't change the content itself really by filtering) the reencoding should work too.
    I don't know of any tool which specifically handles hdr content.
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    Sounds good, thank you!
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  6. Member Ennio's Avatar
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    Next to RPU metadata, note that Dolby Vision authored with FEL carries an extra videotrack which holds the differential data between 10-bit and 12-bit color.
    I wouldn't know if, and with what tool such videostreams can be edited.
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    Yes, I will need to do some playing around. The HDR stuff is all very new to me. I suspect that assuming I can locate closed GOP boundaries, or at least encode some GOP boundaries around my desired cut point in the main HEVC stream, then something like mkvmerge will "slice" through all the layers/streams and I won't have to do anything with the additional layers. But this is all speculation on my part. I don't know if the metadata or secondary video stream can even be cut and appended like that. Hopefully the secondary stream doesn't have GOP issues of it's own!

    I know that FEL layer causes problems for playback (e.g., red shift on Nvidia Shield). Dovi_tool has an option to convert that to standard MEL, but I don't know what the repurcusions of that are. I believe that secondary layer is just discarded, so some information is probably lost.
    Last edited by Travillion; 17th Nov 2021 at 12:23.
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  8. Member Ennio's Avatar
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    Within mkv container, mkvmerge supports "single track dual layer" according to its Dolby Vision support status: https://gitlab.com/mbunkus/mkvtoolnix/-/wikis/Dolby-Vision-support-status
    MakeMKV creates these. Whether making cuts goes well I've never tried TBH. Of course you can give it a go.

    I doubt if presence of FEL has anything to do with Shields redpush. IIRC the issue was also mentioned when playing single layer DoVi.
    What does dovi_tool when converting to MEL? Would it ignore FEL and create a dummy MEL to hold RPU?
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    Originally Posted by Ennio View Post
    Within mkv container, mkvmerge supports "single track dual layer" according to its Dolby Vision support status: https://gitlab.com/mbunkus/mkvtoolnix/-/wikis/Dolby-Vision-support-status
    MakeMKV creates these. Whether making cuts goes well I've never tried TBH. Of course you can give it a go.
    Of course! I knew that, I swear.... I've read so much about this the last few days that I think all this info is now just swimming around my head in a non-sensical mess.

    I doubt if presence of FEL has anything to do with Shields redpush. IIRC the issue was also mentioned when playing single layer DoVi.
    What does dovi_tool when converting to MEL? Would it ignore FEL and create a dummy MEL to hold RPU?
    That could be. I have the 2017 Shield so that won't be pushing the Dolby Vision anyway. I'm *hoping* my TV will play the DV files from its native Plex app, which I've heard a lot of conflicting information about. If not, then I'll just have to settle for HDR10 fallback on my DV titles. My understanding is the FEL layer just gets discarded when dovi_tool creates the MEL layer. So yes, some data is lost, but people seem to think it's still better than plain HDR10.
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  10. Member Ennio's Avatar
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    Originally Posted by Travillion View Post
    ...but people seem to think it's still better than plain HDR10.
    IMO HDR10 plus dynamic metadata - whether that be HDR10+ and/or DV RPU - is definitely worth it and looks significantly better than without.
    Many people would even prefer HDR10+ over DV. Matter of taste I guess.
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  11. Member Ennio's Avatar
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    Originally Posted by Ennio View Post
    Within mkv container, mkvmerge supports "single track dual layer"...
    Come to think of it, for dual track dual layer maybe you can try tsMuxer's split & cut features? Just a thought.
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