HDR and Dolby Vision

HDR10

The open static-metadata HDR format

HDR10 is what most 4K discs and streaming apps actually send. Everything a display does with it comes from a small packet of metadata, and on the Diva that packet is something you can read, rewrite or stop.

HDR10 is the baseline high dynamic range format, published as an open and royalty free specification in 2015, which is why every UHD Blu-ray player, console and streaming box supports it. Three things define it: the SMPTE ST 2084 transfer function, better known as PQ, BT.2020 colour primaries, and at least 10 bits per component.

Its metadata is static. One descriptor covers the whole title and is sent repeatedly in an HDR infoframe alongside the picture, carrying the transfer function in use, the mastering display primaries and white point, the maximum and minimum mastering luminance, and MaxCLL and MaxFALL. The display reads those numbers and decides how to tone map content brighter than it can reproduce. None of it changes the video itself: strip the infoframe and the same pixels arrive looking washed out, because the display has stopped applying the PQ curve to them.

HDR10 on the HDfury Diva

The HDR/DV section is where all of this lives. CAPTURED HDR METADATA shows the infoframe the source is sending, in hex and deciphered into human readable form, and CAPTURED AVI METADATA does the same for the format and colorimetry packet beside it. The OLED has an HDR INFO page reached by cycling with the INFO button, and the OSD can put HDR info and HDR IF onto the picture itself.

Below that sits the custom HDR metadata generator. Set EOTF, Primaries, White Point, Max Luminance, Min Luminance, MaxCLL and MaxFALL, click Create IF, and the resulting hex appears in the text box. Nothing is injected until you tick one of the mode boxes, which are all unchecked by default: custom HDR unconditionally, custom HDR only when the input is HDR10, which is the setting that replaces incoming HDR10 metadata with yours, or only when the input is HLG. The IP command for the HDR10 case is set hdrcustomhdr10only on.

Cancelling HDR10 rather than changing it

Three disable options sit in the same list and they are deliberately surgical. Disable output HDR when the input is HDR10 cancels HDR10 while HLG still passes through; the HLG version does the reverse; disable all output HDR stops everything. The commands are set hdrdisablehdr10only on, set hdrdisablehlgonly on and set hdrdisable on. The feature was added so JVC projector owners could apply their own gamma curves to HDR content and keep the dynamic iris working, and it suits any display that allows a custom gamma curve on the incoming signal.

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