Incorrect clipping for high dynamic range mastering display color volume metadata

[palexander-14]

vpl-gpu-rt/_studio/mfx_lib/encode_hw/av1/agnostic/base/av1ehw_base_hdr.cpp

Lines 42 to 57 in e6a12d5

	inline mfxStatus CheckAndFixMasteringDisplayColourVolumeInfo(mfxExtMasteringDisplayColourVolume* pMDCV)
	{
	mfxU32 changed = 0;
	changed += CheckOrZero<mfxU16, MFX_PAYLOAD_OFF, MFX_PAYLOAD_IDR>(pMDCV->InsertPayloadToggle);
	changed += CheckMaxOrClip(pMDCV->WhitePointX, 50000u);
	changed += CheckMaxOrClip(pMDCV->WhitePointY, 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesX[0], 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesX[1], 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesX[2], 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesY[0], 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesY[1], 50000u);
	changed += CheckMaxOrClip(pMDCV->DisplayPrimariesY[2], 50000u);
	return changed ? MFX_WRN_INCOMPATIBLE_VIDEO_PARAM : MFX_ERR_NONE;
	}

The implemented clipping of primary_chromaticity/display_primaries parameters is incorrect as it limits primary_chromaticity_y to the value of 0.762940, but it must be the 0.840000 (according to the range derived from AVC/HEVC/VVC specs).
To meet this requirement the upper limit of DisplayPrimariesY must be at least 55050.

Related specs:
https://aomediacodec.github.io/av1-spec/#metadata-high-dynamic-range-mastering-display-color-volume-semantics
D.2.29 of Rec. ITU-T H.264 (V15) (08/2024), dl link

BTW, AV1 specification does not set limits for HDR MDCV values (other than those determined by syntax).