Dolby Vision now possible through MP4 Mux.

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Hmm, so if we had a cmv4.0 DV test pattern, would we expect better conformance to that test pattern on ATV?

No, I tried a 4.0 version of this pattern and it's the same issues. (At least on the C2 and Shield)

But I think I read about Stacey Spears saying that Dolby ordered a bunch of their new benchmark discs so maybe that will be improved in the future.

[aboulfad]

…
But I think I read about Stacey Spears saying that Dolby ordered a bunch of their new benchmark discs so maybe that will be improved in the future.

That’d be funny, Dolby Labs using S&M test patterns. I wouldn’t hold my breath between Dolby & Apple to have something changed anytime soon.

If you take a guess, what do you think would be impacted when viewing a movie based on the difference(s) of ATV’s processing of that one pattern?

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It it possible to skip ProRes generation while converting HDR10+ to DV (using 3-1) or is it just better to use the old method if I want to do it quickly?

no
cm analyze requires a prores file.

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If you take a guess, what do you think would be impacted when viewing a movie based on the difference(s) of ATV’s processing of that one pattern?

No idea compared to your oppo but I prefer the PQ of the ATV better than the Shield.

[aboulfad]

No idea compared to your oppo but I prefer the PQ of the ATV better than the Shield.

Sorry I wasn’t clear. Knowing that the ATV has some clipping (Y low, Cr Low), does that translate in some perceivable difference for Picture Quality(PQ)?

I recall that Y(Luma) tends to be more important than Cr/Cb , I wonder if we’d expect crushed blacks or whatever ...

Doing back to back comparison with Oppo is difficult bcoz it takes like 5s on my TV to switch from DV to whatever then to DV. so I found it hard to do that comparison.

I copied inline the S&M explanation for that area of the pattern:

Clipping
Y high / low and Cr high / low

These boxes test whether the Y’CbCr channels are getting clipped at the reference high / low levels before being converted to RGB. This is always wrong; clipping should always be done as late as possible in the display pipeline, and certainly only in RGB.

If Y’CbCr is being kept intact until RGB conversion, there should be clearly visible lighter or darker small squares in the center of each of the four larger squares. If one or more of the channels in Y’CbCr is being clipped, one or more of the smaller squares will not be visible.

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I still dont know how this reflects in real content but the problem seems to be more than just clipped channels because IIRC, the whole square turns black instead of green/red as on cmv2.9 devices or in the SM docs.
If that was just a clipping problem you just wouldn't be able to see the lighter/small red/green square.

[aboulfad]

^^^ thanks for your replies, indeed the Ylow & CrLow squares are black. I just thought maybe I can send the ATV screenshot to S&M and ask. Buying their new UHD disc would be the official way to get some of their support : )

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@Stacey usually responds to users questions here: https://forum.blu-ray.com/showthread.ph ... 27&page=41

[aboulfad]

@Stacey usually responds to users questions here: https://forum.blu-ray.com/showthread.ph ... 27&page=41

Awesome, thank you ! I’ll read the 50 or so pages & post there. Tons of info, I’ve found two posts by Stacey that may be relevant to that test pattern, ATV & clipping (unsure if it’s about SDR only)
1. https://forum.blu-ray.com/showpost.php? ... tcount=878
2. https://forum.blu-ray.com/showpost.php? ... count=1224

[RESET_9999]

@Stacey usually responds to users questions here: https://forum.blu-ray.com/showthread.ph ... 27&page=41

Awesome, thank you ! I’ll read the 50 or so pages & post there. Tons of info, I’ve found two posts by Stacey that may be relevant to that test pattern, ATV & clipping (unsure if it’s about SDR only)
1. https://forum.blu-ray.com/showpost.php? ... tcount=878
2. https://forum.blu-ray.com/showpost.php? ... count=1224

yeah the 2nd link is about the green push in SDR. HDR does not have this problem

[aboulfad]

yeah the 2nd link is about the green push in SDR. HDR does not have this problem

Thanks for confirming, reading more & more just confirms to me as a noob there’s so much more to learn & try. I want to buy that UHD disc but unsure how many DV patterns there are that could be useful to me.

I re-watched some videos from HDTVtest about the first ATV 4K DV comparison between iTunes streaming (P5) & UHD BD (Oppo), the differences were very minor. Maybe in the end, it (UHD MEL to P8/ATV) doesn’t matter, oc what no one can agree or find info on is the color mode/space differences from UHD P7 to P8 to whatever the ATV is doing internally.

One thing I’ve learned is that DoVi is just a whole pile of mess ; - )

[jlpsvk]

so...does the latest atv4k 2022 play dovi p8 correctly from mkv in plex client? or still as fake dovi?

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Plex still does fake DV but with Infuse, P8 MKV, and TS works (with lossless audio being decoded as lpcm audio and you can access your plex server with infuse). The picture quality is better than on the Shield from the quick tests I did but I want to do a full comparison soon. It doesn't support cmv4.0 files though, they play as HDR10.

EDIT: example: https://slow.pics/c/41eRbGZ4

[jlpsvk]

thanks reset... so i will stick with Plex on my OLED Android TV for now.

[LV8HD]

Hi y'all, I would like to generate a custom HDR10+ layer for a movie with Davinci Resolve, but a doubt came to my mind. The movie is in fact a FEL movie, and since it expands the brightness of the BL what would be the most correct way to generate the custom HDR layer?

1. Measuring only the BL
2. Baking FEL and BL together to create a HDR10 video and measuring