Dynamic conversion of HDR10+ SEI to DV P8 NAL

[cpm]

It is a general DV tv-led issue not specific to this conversion case, with tv-led the display is sent the whole image including at that point the subtitles baked into the image, it then tone maps the whole image including those baked in subtitles.

This on-the-whole went unnoticed when the UI (and hence subtitle) brightness was at 100%, and started to be noticeable when bringing down the UI brightness (GUI luminance), which when further being tone mapped at the TV side can become quite dull and the variability is more noticeable in this lower brightness range.

Here is more discussion I had on that earlier if interested:

Dolby Vision - VS10 Engine on Ugoos AM6+

I would presume talking about generated text from SRT etc, where it is putting out a constant luminance but the display is adjusting the whole screen including the constant luminance subtitles based on the RPU in DV-Std. Would be interesting to known if the same happens for DD-LL, I would guess maybe not, as RPU maybe applied to the video only and then OSD overlayed. In order for it not to go up and down with the RPU I think would need to interpret the the RPU and apply an inverse adjustment t…

---

It was on my list of enhancements when I had the ambitious goal that could make this the best DV device for tv-led.

Would have gone something like.

1. First step put the GUI luminance control under keyboard / remote control - so could adjust to find a sensible balance on the fly.(you can bring up the UI now when playing and adjust on the fly so quite doable just need to marry that control with keyboard I guess)

2. Extract a brightness level from the RPU and apply that in-reverse to the GUI luminance control to reverse some of the effect of the tone-mapping (maybe need some manual adjustment to dial in per display) - Say some of the effect as likely still want the subtitles to tone down in dark scenes - but not to the extent it is distracting.