HDMI signals

HDMI

High-Definition Multimedia Interface

HDMI is the connector on the back of everything you own, and also a set of rules about what may travel down it. The Diva sits in the middle of those rules and rewrites several of them.

HDMI stands for High-Definition Multimedia Interface. It first shipped in 2003 and replaced the separate video and audio cabling of the analogue era with one link carrying uncompressed video, up to eight channels of audio, control messages and copy protection at the same time. The video travels as TMDS on three data pairs plus a clock, and the audio and the small description packets called infoframes are tucked into the blanking intervals between picture lines.

Each version since has been about bandwidth and about what you are allowed to describe with it. HDMI 1.4 reached 4K at 30Hz. HDMI 2.0 raised the ceiling to a 600MHz pixel clock and 18Gbps, which is exactly what 4K60 4:4:4 8-bit needs, and 2.0a and 2.0b added HDR10 and HLG signalling. The parts people argue about, HDCP revisions, CEC, ARC and EDID, are all carried inside HDMI rather than being separate systems bolted alongside it.

HDMI on the HDfury Diva

The Diva is an HDMI 2.0b device with four inputs and three outputs, and each port negotiates on its own. The receiver block decrypts an input first, then each output encrypts individually to HDCP 1.4, to 2.2, or not at all if the source was never encrypted. That is why the manual's answer to which HDMI version you need is that it does not matter: the Diva works with any version from 1.0 upwards.

• Inputs 1 to 4: all equal, each accepting up to 4K60 4:4:4 at 600MHz and 18Gbps, so there is no preferred one to start with.
• TX0: the 18Gbps video output, the one the scaler upscales, and the CEC, ARC and eARC capable output.
• TX1: the 1080p SDR downscale output, which also drives the ambient light strip and the lag tester.
• HDMI audio output: a self-generated 720p or 1080p stream carrying full audio to any AVR input.

Which input feeds which output is set in the INFO section port selector, with the OUT0 and OUT1 buttons on the unit, or over IP with set inseltx0 1. Delay through the box is in the order of a few pixel clocks, so the Diva is not what you blame when something feels late.

The cable rules that come with 18Gbps

Any HDMI cable in the chain must support 18Gbps if an 18Gbps source or sink is connected to it, which in practice means the inputs and TX0. TX1 and the audio output never carry more than 1080p or a self-generated 720p or 1080p stream, so an ordinary high speed cable is fine there. For a 600MHz link, HDfury suggests cables certified or tested for 600MHz, ideally between 6ft and 12ft. The Diva acts as a repeater, amplifying and recovering the signal, so placing it in the middle of a long run often removes the need for a separate amplifier.

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