Shrink 4K UHD with Dolby vision

[moon_light]

I use TSMuxer to create UHD ISO, and then use ImgBurn to burn to disc BD66 and BD100, but the BD66 and BD100 discs cannot be played on my Panasonic UHD 820 Player. Is there any way to compress the 4K UHD BD66 and BD100 discs into BD50 disc? I hope to keep 4K HEVC Dolby Vision, thank you!

[Ennio]

Never tried so far but here's a link that says ISO can be created from Dolby Vision Profile 8.

https://forum.redfox.bz/threads/create-dolby-vision-iso-from-a-profile8-bl-rpu-mkv.87159/

Which would mean you'd first have to create DoVi P8 from your UHD ISO.

[moon_light]

Never tried so far but here's a link that says ISO can be created from Dolby Vision Profile 8.

https://forum.redfox.bz/threads/create-dolby-vision-iso-from-a-profile8-bl-rpu-mkv.87159/

Which would mean you'd first have to create DoVi P8 from your UHD ISO.

Thank you for your reply. Can I directly compress BL stream to generate a new BL stream, and then use it to replace the original BL stream?

[Ennio]

If you mean replacement next to native EL, the answer is no. It's been tried many times. Where I've learnt BL and EL need same frametypes order. Recoding BL obviously destroys its native order.

Converting to P8 means having BL only (recoded or not) and "inject" it with RPU (DoVi's dynamic metadata). At which point you must be careful. On UHDBD (DoVi Profile 7), note that RPU is always authored to be applied on full outcome of combined BL and EL. Where in case of EL being FEL (Full Enhancement Layer) it's often not recommended to use RPU for P8.

That having said, I am at the very moment looking into "DoViBaker". It can take FEL's additional videodata and apply it on BL, prior to recoding. Whether the outcome can be combined with P8-converted RPU and how all works out I yet have to learn.

[EDIT] Having read more on dovibaker, I understand it uses FEL's both RPU and videodata to merge with BL into one videostream.

[moon_light]

Because the m2ts file of the UHD disc already contains the double-layer Dolby Vision, I want to keep the EL+RPU layer without doing any processing, and then use handbreak to compress the BL stream, which is a 4K HEVC 10bit HDR video with a large amount of data (high bit rate), and then replace the original BL stream with the compressed video, and finally use TSMuxer to generate 4K UHD ISO.

[Attachment 74603 - Click to enlarge]

[moon_light]

Because the m2ts file of the UHD disc already contains the double-layer Dolby Vision, I want to keep the EL+RPU layer without doing any processing, and then use handbreak to compress the BL stream, which is a 4K HEVC 10bit HDR video with a large amount of data (high bit rate), and then replace the original BL stream with the compressed video, and finally use TSMuxer to generate 4K UHD ISO.

[Attachment 74603 - Click to enlarge]

[johns0]

Just use mkvmerge to split the m2ts into 2 parts and use what ever program you want to burn to 2 50gb discs without any encoding.

[Ennio]

Because the m2ts file of the UHD disc already contains the double-layer Dolby Vision, I want to keep the EL+RPU layer without doing any processing, and then use handbreak to compress the BL stream...

I already understood your intention. But like I said

If you mean replacement next to native EL, the answer is no. It's been tried many times. Where I've learnt BL and EL need same frametypes order. Recoding BL obviously destroys its native order.

Do consider that should EL be MEL (Minimum Enhancement Layer; this only carries RPU), P8 is equivalent as it will contain all video- and DoVi metadata that is on disc. So in which case, as a valid intermediate to the link in my first post, you can recode BL and first create a P8 file.
Your tsMuxer's screenshot doesn't show whether EL is FEL or MEL.

[moon_light]

M2ts of UHD discs are double-layer DV, so they are FEL, not MEL. they are profile 7

[Ennio]

Not true. P7 is indeed double layer. BL and EL. Where EL is always either MEL or FEL.

FYI https://forum.blu-ray.com/showthread.php?t=276448

[moon_light]

Thank you, you provided very important information!

[Ennio]

You're welcome. You can check for yourself whether a Dovi disc has MEL or FEL by importing it in MakeMKV. When you go to the videosection's properties, it will show either MEL or FEL.
Also, often it can be told by MediaInfo. Though it doesn't directly provide with MEL or FEL in words, EL's bitrate and/or streamsize can tell.

[moon_light]

Thank you! I used DVDFab UHD Creator to load an M2TS file containing double-layer DV, and then used transcode mode to make it into UHD. I found that compared with the original M2TS ES stream, its EL stream was basically unchanged, except for a few bytes.
The BL stream is compressed.

[Ennio]

If EL barely changed in size I'm guessing your UHDBD has MEL. And possibly the same as described in my link will be done. It also uses DVDFab where I reckon a dummy MEL is created, which only carries RPU.

I wonder how DVDFab would behave when feeding P7 FEL in this "transcode mode". I'm afraid FEL's additional videodata will be ignored and only RPU will be used in a dummy MEL. At which point not all videodata is in the endresult, which playback experience may/may not be as intended.

As such, I'm curious to what DVDFab can conjure up with when feeding it Saving Private Ryan. It's a notorious FEL title that's said to have severe non-constant luminance changes by FEL which are compensated when RPU is applied on composer output. However I don't intend to spend any time nor dime on both the movie and software.

[moon_light]

Is there any way to tell whether a HEVC stream is FEL or MEL?

[Ennio]

Yes, if you're willing to read.

You can check for yourself whether a Dovi disc has MEL or FEL by importing it in MakeMKV. When you go to the videosection's properties, it will show either MEL or FEL.

[moon_light]

This method is possible, I have succeeded, it works on Panasonic DP-UB820, I encode the BL stream directly, and then composite it with the original M2TS, below is my handbreak setting.
[Attachment 74740 - Click to enlarge]
[Attachment 74739 - Click to enlarge]

[Ennio]

I take it your disc was MEL?

[moon_light]

I don't know whether it is FEL or MEL. It shows 12 bit Dolby Vision, I tested it with makemkv, but I don't know where to display this information. Could you take a screenshot and show it to me? thank you!

[Attachment 74761 - Click to enlarge]

[Ennio]

Makemkv screenshot outtake.


[Attachment 74762 - Click to enlarge]

[moon_light]

Got it, thank you! It seems to be mel.

[Ennio]

I thought so. Try to do the same procedure with a FEL title and see what it results to.

[moon_light]

I checked all my UHD discs and they are all MEL(original disc).