Audio

HBR audio

High Bit Rate audio over HDMI

HBR is the reason a lossless soundtrack has to travel by HDMI. Knowing which Diva output can carry it saves a long argument with an amplifier that keeps reporting the wrong format.

HBR stands for High Bit Rate audio, added to HDMI in version 1.3. A single IEC 61937 stream of the sort S/PDIF carries tops out at about 6.144 Mbit/s. That is comfortable for Dolby Digital, DTS and Dolby Digital Plus, and nowhere near enough for Dolby TrueHD or DTS-HD Master Audio, which are lossless and therefore variable and large.

HBR solves it by spreading one bitstream across all four of the audio sample packet slots HDMI provides, giving roughly four times the rate, up to around 24.576 Mbit/s. The consequence is the part that catches people out: HBR is an HDMI only transport. No optical or coaxial cable carries it at any quality, which is why a lossless track arriving over S/PDIF is really its lossy core. Since Atmos rides inside TrueHD and DTS:X inside DTS-HD Master Audio, an optical link cannot carry those either in their full form.

Where HBR audio can go on the HDfury Diva

HDMI audio output

A self generated 720p or 1080p stream carrying full audio, made to feed any amplifier input. This is the output to use when you want every format your amplifier can decode, including Atmos HBR over TrueHD pulled back from an eARC television at TX0.

TX0

Any HDMI sound format in existence today passes through the inputs and TX0 intact, so a television or amplifier here can have the lot.

TX1

Full HDMI sound and video for equipment that is only capable of 1080p, in HDR or SDR.

SPDIF or L/R analogue jack

Optical carries up to 5.1 and the analogue side is stereo, so no HBR format leaves here. The manual is direct about it: lossless audio is transmitted through the HDMI output only.

The Diva does not compress or downconvert incoming audio, and performs no format manipulation at all, so the practical limit is your amplifier rather than the unit.

Making the source send it in the first place

A source only sends what the EDID claims, so an HBR format that never appears is usually an EDID question. In Automix the audio flags are 2.0 Stereo, 5.1 Multi and 7.1 Full, along with TX0, TX1 and AUDIO OUT, which force the mixed EDID to present the audio capability of one particular sink. AUDIO OUT is the one to reach for when the amplifier is fed from the dedicated HDMI audio output, since otherwise the mix is being made out of two displays that have nothing to do with it. The command is set edid audio with values stereo, 51, full, native or tx1. Among the 90 predefined tables each video format appears in All Sound, SPDIF and Stereo variants, so pick an All Sound table if you are working in CUSTOM mode.

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