How to tell if a video file has color outside rec.709 in rec.2020?

Teagan wrote on 7/28/2020, 9:38 PM

After discovering that my V-Log on my Panasonic AG-CX350 is only in rec.709 I started to wonder about the rec.2020 in the HLG setting, if that is just rec.709 in a rec.2020 container.

I came across some interesting information regarding 4k blu rays from HDTVTest, on youtube, in the following video:

He shows that 4k HDR blu rays are mainly DCI-P3 inside a rec.2020 container BUT not all of them, but most.

Now how would I determine if my camera's video files have color values outside of the rec.709 and/or DCI-P3 color spaces in a supposed rec.2020 video file without buying the Sony BVM-HX310 he used to test this, which, by the way, costs more than a new car?

I have emailed Panasonic's pro video email and they have not answered me on this. They usually have answered me on many things within a couple days.

Comments

Musicvid wrote on 7/28/2020, 10:17 PM

What does MediaInfo say?

Teagan wrote on 7/29/2020, 8:33 AM

What does MediaInfo say?

Video
ID                          : 1
Format                      : HEVC
Format/Info                 : High Efficiency Video Coding
Format profile              : Main 10@L5.2@High
Codec ID                    : hvc1
Codec ID/Info               : High Efficiency Video Coding
Duration                    : 42 s 42 ms
Bit rate                    : 192 Mb/s
Width                       : 3 840 pixels
Height                      : 2 160 pixels
Display aspect ratio        : 16:9
Frame rate mode             : Constant
Frame rate                  : 59.940 (60000/1001) FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 10 bits
Bits/(Pixel*Frame)          : 0.386
Stream size                 : 962 MiB (98%)
Language                    : English
Encoded date                : UTC 2020-03-09 22:58:13
Tagged date                 : UTC 2020-03-09 22:58:13
Color range                 : Limited
Color primaries             : BT.2020
Transfer characteristics    : HLG
Matrix coefficients         : BT.2020 non-constant
Codec configuration box     : hvcC

 

Musicvid wrote on 7/29/2020, 10:12 AM

The dynamic range is 10 bits after transform. The color gamut is equivalent to 709, I believe.

Do you actually have a monitor with a hardware gamut wider than REC 709?

Teagan wrote on 7/29/2020, 10:18 AM

The dynamic range is 10 bits after transform. The color gamut is equivalent to 709, I believe.

What does that mean, exactly? And is this why HLG is backwards compatible, without doing color space remapping if colors were out of that range, so it's just rec 709 in a rec 2020 container and a 709 TV just reads it as 709?

Also, is there any software that can do what that monitor does, to see if color values are outside of rec 709, DCI-P3, etc?

Musicvid wrote on 7/29/2020, 10:25 AM

Oh. You've got homework. The internet is your best teacher.

Teagan wrote on 7/29/2020, 10:49 AM

To answer the other question, yes my main 1440p (8 bit + FRC) monitor is 95% of DCI-P3 and I have a 4k (8 bit + FRC) TV via HDMI that supports HLG/rec 2020. My 4K (true 10 bit) monitor supports only 100% sRGB.

Teagan wrote on 7/29/2020, 1:39 PM

Oh. You've got homework. The internet is your best teacher.

Ok I did some homework and found an easy way to find my answer. The problem is that I believe I need the full studio version of Davinci Resolve to use their CIE Chromaticity scope with the HDR scopes enabled. I clicked to show the additional gamut of rec 2020 as well as rec 709. Here's what it says for the following file with the following media info:

The footage comes from here https://4kmedia.org/sony-swordsmith-hdr-uhd-4k-demo/

So I believe I need to have the option "Enable HDR Scopes for ST.2084 and HLG" enabled to have this scope show anything beyond rec.709? I don't think this professional footage with the following info should show it being limited to 709. I have tried multiple files from the website I got this sample from and I don't believe all their super HDR samples are all 709.

Video
ID                          : 1
Format                      : HEVC
Format/Info                 : High Efficiency Video Coding
Format profile              : Main 10@L5.1@High
HDR format                  : SMPTE ST 2086, HDR10 compatible
Codec ID                    : hvc1
Codec ID/Info               : High Efficiency Video Coding
Duration                    : 1 min 26 s
Bit rate                    : 71.4 Mb/s
Maximum bit rate            : 114 Mb/s
Width                       : 3 840 pixels
Height                      : 2 160 pixels
Display aspect ratio        : 16:9
Frame rate mode             : Constant
Frame rate                  : 59.940 (60000/1001) FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0 (Type 2)
Bit depth                   : 10 bits
Bits/(Pixel*Frame)          : 0.144
Stream size                 : 733 MiB (100%)
Encoded date                : UTC 2016-10-24 06:29:51
Tagged date                 : UTC 2016-10-24 05:33:22
Color range                 : Limited
Color primaries             : BT.2020
Transfer characteristics    : PQ
Matrix coefficients         : BT.2020 non-constant
Mastering display color pri : R: x=1.000000 y=1.000000, G: x=1.000000 y=1.000000, B: x=1.000000 y=1.000000, White point: x=1.000000 y=1.000000
Mastering display luminance : min: 0.1000 cd/m2, max: 1 cd/m2
Codec configuration box     : hvcC

 

Here's a sample of the scope with my HLG footage that I posted the media info of in a few posts ago:

and my V-Log:

 

Do you have the studio version of Davinci Resolve to see if that sample footage I linked is showing values outside of the rec 709 space with the HDR scopes enabled?

Musicvid wrote on 7/29/2020, 2:04 PM

Thanks for finding that. I think you would need to work with transformed, not native V-log, to show the unpacked gamut.

Keep sharing your learning experience.

Teagan wrote on 7/29/2020, 2:35 PM

Thanks for finding that. I think you would need to work with transformed, not native V-log, to show the unpacked gamut.

Keep sharing your learning experience.


Yes that is just raw VLog from the camera, no LUTs nor grading - that's no problem. I just wonder if the HDR scopes option in davinci is my problem with the HLG or if I'm just stuck with 709 on everything.

Here's that Vlog with the Panasonic Vlog rec709 LUT without any tinkering:

 

Musicvid wrote on 7/29/2020, 5:36 PM

I found out the Sony A7R II and III shoots full Rec 2020. That's possibly your best option under $10k.

Teagan wrote on 7/29/2020, 5:47 PM

I'm personally looking for either the Panasonic GH6 which should be announced in like a week or two or the older GH5S.

I'm not really looking to invest more than $3000 at the max, which means I'm probably going to the GH5S unless the GH6 price is good.

I'm also thinking of buying a budget HDR grading monitor with FALD 384 zones, 1000 nits and rec 2020 coverage like the Dell UP2718Q 27". But if my TV camera doesn't support rec 2020 there's no real reason to get that.

I'd probably just stick with TVs for now. The GH6 with 6K and possibly 8K would be very nice, though.

So you think the GH6 and GH5S will do the same with rec. 2020 that my AG-CX350 does?

Also, to be honest, the GH5S specs looks like a downgrade from the AG-cx350.

Musicvid wrote on 7/29/2020, 6:12 PM

You are well outside my comfort zone by now. Best of luck.

Teagan wrote on 7/29/2020, 7:40 PM

Sorry for that. On the other hand I just figured out my problem with that scope, my timeline was set to 709. I changed it to Rec.2100 HLG and look at what I see now on the scopes! Colors are outside of the rec.709 space!

Thanks for the guidance. I appreciate it and I now appreciate my camera more as well!

Now, the next thing to learn is whether to use Rec.2100 HLG, Rec.2100 ST2084 or a similar one...

Here's the video after I click auto color in Davinci and have it set to Rec.2100 ST2084. Looks great. Hopefully it's not just stretching out 709 to look like this but the colors are accurate on the color card. It seems to be transforming my preview to sRGB or something automatically. I think.

Ok I rendered and everything is super saturated. It looks like I need to change my input color space and gamma sort of like I have to set my input color space in Vegas. The problem is that I can't do that perfectly on the free version of Davinci since I have no HDR features nor scopes that I need but I have them in Vegas. I am working around that by turning the video into a regular rec 2020 video in vegas pro without an HDR preset and then importing it into Davinci. In vegas I have to trick it into thinking the HLG is rec 2020 ST2084 1000 nits (in input color space on project media) to have it display properly.

That did not work but I did find out I can set the input on Davinci to 2020 and St.2084 1000 nits like I have to on Vegas and that made things look proper (being washed out on my pc screen). I don't know why I can do that on the free version, as I would think that's an HDR feature. I can output from there to a .mov h.264 file but my TV can't read that file format from USB to see if it is really rec 2020. My LG C9 OLED can though, but it looks exactly like it does on my sRGB/DCI-P3 monitors, just washed out, as rec 2020 content should on that screen but why it was ALSO on the rec 2020 capable TV, I don't know. The output file from davinci has no luminance information nor any HDR10 flags like I can do on Vegas for it to work perfectly, which the same source file from Vegas, trying to do what I'm doing on Davinci, works with no issues on the LG C9 OLED. I was also limited to 8 bit on davinci.

I guess I will need a studio license to output HDR10 for this to all work on Davinci if I want it to.

Here's my screen and I believe the scope is correct in showing there's colors outside the rec 709 area, but I'm not 100% sure anymore.

Here's another scope screen grab of when the camera is looking at a more colorful area, which shows many points outside the 709 area.

This is very complicated and confusing. Time for a break for today.

I tried this with a known rec 709 video with the same exact settings for input and gamma and that scope doesn't let any color show outside the 709 triangle.

Teagan wrote on 8/1/2020, 12:09 PM

I was about to say I was stumped and this is over but I have found my answer and I'm sure of it this time:

I initially put a known rec 709 video in the Davinci timeline and set the color space of the input and timeline to rec.2100 st2084 and was very confused why it was showing colors outside of the rec 709 triangle but came to the conclusion that the video just had artifacts that had some rare spots of color outside of that color space. Nothing major was being shown outside of the 709 triangle - just the random spot like this: (note this is a dark scene)

and

--------------------------

So I set my davinci timeline color space to color managed, input, timeline and output to rec.2100 st2084 and this time also limit output gamut to rec. 2020. That's all I changed on the color settings page in davinci.

So with that set I decided to put an HLG rec 2020 clip AND a regular rec 709 clip in the same timeline to see if that would solve some of this confusion by eliminating the problem of not choosing the correct color spaces for each clip (I also tried all rec 2020 related color settings to be sure I was using the correct one at least once, but I know the correct one for vegas but davinci is very odd regarding the naming so that's where the problem comes from).

All my rec 709 clips would not show any (major) color outside of the rec 709 triangle and my HLG 2020 clip is showing major amounts of color outside of the rec 709 triangle on all sides, depending on which clip I'm looking at. This was on all of the rec 2020 related color settings. I believe that the rec.2100 st2084 is the correct input color space as the one I use in vegas pro is rec. 2020 st2084 1000 nits. I believe this is so, because this is what an HLG HDR TV would use when it detects this HLG file, since how HLG works and the backwards compatiblity, etc.

Here's my HLG 2020 video in the correct color space of Rec.2100 ST2084: (scene of my lawn through a window in my house with a blue couch)

And here's the 709 clip in the same color space settings as the scene above: (very bright clip from a show I recorded a year or two ago for a client)

-----------------------------------

So to come to a conclusion, my camera is true rec 2020 in the HLG setting and I still don't know why Panasonic pro video won't answer my emails. Perhaps they are backed up because of too many requests or they think I'm too nosy with what I'm asking. Haha.

-----------------------------------

EDIT: adding on to this, to not bump it, my HLG rec.2020 is very unsaturated so I had to turn that up 70% (may change little higher or lower if I look with a color card) for it to look natural and in doing so, it fills up the scope way more in the 2020 triangle. In davinci this is to 85 from the default 50. In Vegas pro it's 1.7 saturation, same thing but different way of saying it.

This is very easy to see it's more correct when I do a transform from hlg 2100/ rec 2020 to rec 709/gamma 2.4 as I am not viewing this on a rec 2020 monitor.

Here's the scope while in rec 2020 on davinci's timeline with the proper saturation (85.0 from 50.0 default):