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Old 10th October 2017, 14:18   #1  |  Link
d3rd3vil
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How to detect Dolby Vision in a videofile?

Ladies and gentlemen,

the issue at hand is about Dolby Vision

Does anyone have an idea how to detect DV in a videofile? For example MediaInfo doesnt seem to have the appropriate info whether DV is in the file or not.

For example this TS Dolby Vision file right here:
https://drive.google.com/uc?export=d...0RDWVVsWUtRMnM

Dolby Vision works. Tested on an LG Oled with DV capability.
After throwing the TS file in MKVToolNix the MediaInfo is quite similar however DV doesnt work anymore on my tv, its gone or deactivated or whatever. The metadata seems to get lost.

So is there a way to see DV in the TS file to see the difference between the TS and the mkvtoolnix mkv?

Thank you very much in advance

I know DV is still very new and in the early stages more or less. But maybe some of you have an idea for the issue at hand
Waiting for PowerDVD for example is possible of course but it will take months I suppose...

Last edited by d3rd3vil; 10th October 2017 at 14:23.
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Old 13th October 2017, 01:59   #2  |  Link
Balwyn
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Have no explanation for you, however replicated your results with my LG OLED TV, so nothing wrong with your test method.
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Old 14th October 2017, 00:05   #3  |  Link
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As far as I know DV data is inside h265 headers and it's dynamically inserted per scene. It's quite complicated and you can look at x265 documentation to see how it's done. There is some section about it.


update: sorry, I was talking about HDR10+, but DV is about the same.

Last edited by kolak; 14th October 2017 at 13:34.
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Old 14th October 2017, 11:09   #4  |  Link
d3rd3vil
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We need professionals the real Dolby Vision gods to solve the problem someday. We need the good stuff
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Old 14th October 2017, 12:17   #5  |  Link
kolak
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Not sure what you mean. Dolby won't give you anything for free- it's very patenting/money orientated company.
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Old 14th October 2017, 18:36   #6  |  Link
raffriff42
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https://www.dolby.com/us/en/technolo...hite-paper.pdf
Yep, from the looks of this, they really want to lock it down. Gonna require a secret decoder ring, er chip, no doubt...
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Old 14th October 2017, 23:29   #7  |  Link
Blue_MiSfit
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This dual stream technique is not used in practice AFAIK.

Real Dolby Vision implementations (I forget the profile numbers) for OTT VOD are pure 10 bit HEVC with proprietary dynamic metadata stored in SEI messages.
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Old 15th October 2017, 07:31   #8  |  Link
nevcairiel
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Quote:
Originally Posted by Blue_MiSfit View Post
This dual stream technique is not used in practice AFAIK.
On Blu-ray it is.
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Old 20th October 2017, 18:29   #9  |  Link
benwaggoner
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Quote:
Originally Posted by nevcairiel View Post
On Blu-ray it is.
Correct. Although I don't know that it is actually required for discs.

And I have heard at least one streaming provider is currently using dual layer. The single layer is quite a bit more bitrate efficient, so the general trend is to use that instead, But dual layer was available a lot earlier, so that's what a lot of early tooling was built around.
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Old 20th October 2017, 18:36   #10  |  Link
benwaggoner
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Quote:
Originally Posted by kolak View Post
As far as I know DV data is inside h265 headers and it's dynamically inserted per scene. It's quite complicated and you can look at x265 documentation to see how it's done. There is some section about it.

update: sorry, I was talking about HDR10+, but DV is about the same.
They are actually WAY different.

The single layer Dolby Vision uses a non-backwards compatible HEVC 10-bit base layer, using ICtCp and dynamically adjusting so that the 10 bits of precision are mapped to the current video parameters to preserve more precision. The file is absolutely not playable in a general HEVC player; it needs a lot of metadata-driven Dolby algorithms to convert from the non-backwards compatible stream to Dolby's 12-bit ICtCp space, and then using other metadata to go from that to the display, optimizing for the display's characteristics.

HDR10+ is a HDR-10 base layer, plus metadata in the SEI that can be used to improve tone mapping, or ignored. So those streams are playable in themselves in any HDR-10 capable player.

Dolby has a big proprietary display tone mapping library. HDR10+ is really just the descriptive metadata; it's up to each vendor to figure out how to use that metadata in their own tone mappers.
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Old 20th October 2017, 21:09   #11  |  Link
SeeMoreDigital
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Well....

When my Oppo UDP-203 plays typical HDR video sources, the player produces the following info: -
Media Information
HDR Format: BDMV HDR
Colour space: BT2020 YCbCr 4:2:0 @ 10-bit

HDMI(Main) Output Information
HDR Format: HDR
Colour Space: BT2020 YCbCr 4:2:2 @ 12-bit

But when playing Dolby Vision sources, my Oppo produces the following info: -
Media Information
HDR Format: Dolby Vision
Colour space: Dolby Vision @ 12-bit

HDMI(Main) Output Information
HDR Format: Dolby Vision
Colour Space: Dolby Vision @ 12-bit

So somehow a 4:2:0 10-bit (not 12-bit) encoded video stream becomes a uniquely flagged 'Dolby Vision' 12-bit output...
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Last edited by SeeMoreDigital; 21st October 2017 at 22:42.
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Old 21st October 2017, 10:31   #12  |  Link
d3rd3vil
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Well there are 2 things that could be interesting.

1: A software mediaplayer that can play DV material. That will probably be tricky.

2. A way to convert all the relevant data to mkvs or ts formats so the TV can handle the rest and play it.
And the second option should be easier to accomplish?! Of course there are already ts DV files that are no prob for the tv.

Last edited by d3rd3vil; 21st October 2017 at 10:35.
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Old 22nd October 2017, 16:48   #13  |  Link
benwaggoner
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Quote:
Originally Posted by SeeMoreDigital View Post
Well....

When my Oppo UDP-203 plays typical HDR video sources, the player produces the following info: -
Media Information
HDR Format: BDMV HDR
Colour space: BT2020 YCbCr 4:2:0 @ 10-bit

HDMI(Main) Output Information
HDR Format: HDR
Colour Space: BT2020 YCbCr 4:2:2 @ 12-bit

But when playing Dolby Vision sources, my Oppo produces the following info: -
Media Information
HDR Format: Dolby Vision
Colour space: Dolby Vision @ 12-bit

HDMI(Main) Output Information
HDR Format: Dolby Vision
Colour Space: Dolby Vision @ 12-bit

So somehow a 4:2:0 10-bit (not 12-bit) encoded video stream becomes a uniquely flagged 'Dolby Vision' 12-bit output...
DoVi even has a mode to pack pixels into RGB 8-bit over HDMI 1.4 (the technology predates HDMI 2.0). There are several HDMI modes, which different devices might call different things. And older receiver should be able to pass through the weird modes without knowing they are DoVi.
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Old 22nd October 2017, 18:22   #14  |  Link
SeeMoreDigital
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I wonder if it's possible to find some 'repeat information' with a hex editor...
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Old 2nd November 2017, 13:11   #15  |  Link
d3rd3vil
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Why is there no real detection software out yet? And also no mediaplayer for PC that can play the stuff....I dont believe it. Damn it Dolby
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Old 2nd November 2017, 16:13   #16  |  Link
SeeMoreDigital
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Jeez... There's less than two dozen UHD discs currently available (and most of them arn't worth watching). What's the rush?
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Old 2nd November 2017, 17:05   #17  |  Link
d3rd3vil
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No real rush but it looks like we'll have to wait till 2018 at least which is a bit disappointing.
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Old 2nd November 2017, 23:31   #18  |  Link
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mediainfo was updated today, there is something in the changelog about HDR detection, might want to give that a try.
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Old 3rd November 2017, 12:41   #19  |  Link
d3rd3vil
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Nope nothing worth mentioning
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Old 22nd December 2017, 19:35   #20  |  Link
d3rd3vil
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Anyone working on a reverse-engineering of Dolby Vision yet? ^^ For MediaInfo, or TSMuxxer, or sth. else, anything
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