wayland: convert luminance values to libplacebo space #17149
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| float a = wd->min_luma; | ||
| float b = (PL_COLOR_SDR_WHITE - PL_COLOR_HDR_BLACK) / (wd->ref_luma - a); |
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I'm just mapping primary color volume min_luma to PL_COLOR_HDR_BLACK now. I don't know if there is anything more sensible to do.
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You might want to test this with some dark videos to see if the blacks come out as the proper shade of black.
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PL_COLOR_HDR_BLACK is effectively 0, it's just sentinel value to discriminate from "undefined" which is 0.
It shouldn't make a difference.
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That is so, but the goal of this mapping is to ensure that 0 in nominal space A maps to 0 in nominal space B. But 0 in nominal space is usually not 0 luminance. For most SDR transfer functions 0 in nominal space is 0.2 cd/m^2 and for PQ 0 in nominal space is 0.005 cd/m^2. I'd have to know what 0 is in the nominal space assumed by libplacebo.
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Note that it depends on the values in csp. If things are set, they will be used, if not. Default is used instead, which is 0.203 (203/1000) for SDR and 0 for PQ. Generally internal absolute black is always 0 in libplacebo and SDR is shifted according to min_luma value.
float min, max;
pl_color_space_nominal_luma_ex(pl_nominal_luma_params(
.color = &csp,
.metadata = PL_HDR_METADATA_HDR10,
.scaling = PL_HDR_NITS,
.out_min = &min,
.out_max = &max,
));
video/out/wayland_common.c
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| wd->csp.hdr.max_fall = MPMIN(wd->csp.hdr.max_fall, wd->csp.hdr.max_luma); | ||
| } | ||
| wl->preferred_csp = wd->csp; | ||
| if (wd->csp.hdr.max_luma != PL_COLOR_SDR_WHITE) { |
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I changed this to != since that is the only case where it is ok for the rest of mpv to ignore the max_luma.
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Signed-off-by: Julian Orth <[email protected]>
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kasper93
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I think it make sense. We can always improve on case by case basis, should there be any issues.
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This PR contains the first commit from #17070 with some small changes.