Audio

Dolby TrueHD

Lossless Dolby audio

TrueHD is the format most likely to be silently downgraded by something in the chain. The Diva does not alter audio at all, so what reaches your AVR is decided by the EDID.

Dolby TrueHD is Dolby's lossless codec, introduced with the high definition disc formats in 2005 and standard on Blu-ray since. It is built on Meridian Lossless Packing, so decoding returns bit for bit what the studio mastered: nothing is discarded, and the bitrate varies with the content instead of being fixed as it is in a lossy format.

A TrueHD track carries up to 7.1 channels at 24-bit and up to 96kHz on disc, and peaks at several times the rate of a lossy track. Carrying that over HDMI needs HBR, the high bit rate audio transport, which uses all eight channels of the HDMI audio path at four times the ordinary clock. Dolby Atmos on disc rides inside a TrueHD stream as an additional substream, so a decoder that knows nothing about Atmos plays the 7.1 bed underneath and hears nothing missing.

Because of that structure, TrueHD is sent from the player as a bitstream and decoded at the AVR. A player can decode it to PCM instead, but the Atmos objects are lost when it does, and no version of it fits down an optical link.

Dolby TrueHD on the HDfury Diva

The Diva performs no audio format manipulation: what comes in goes out untouched. Any HDMI sound format in existence today passes through the inputs, TX0 and the dedicated HDMI audio output intact, so the practical limit is what your AVR can decode rather than the unit in the middle.

There is a second route in. When a television with an eARC capable input is connected at TX0, the Diva extracts up to Dolby Atmos HBR over TrueHD from it and forwards that to the HDMI audio output, which is how the soundtrack of an app running on the television reaches an AVR with no eARC of its own. Extraction happens automatically and does not rely on CEC, so there is no CEC option to select for it. ARC on an older television tops out at DD+ and Atmos over DD+, which is why an ARC set will never hand you TrueHD.

Making sure the source sends it

A source sends TrueHD only if the EDID it reads says the chain accepts it. If your AVR sits on the dedicated HDMI audio output while a stereo television sits on TX0, Automix reports what both agree on, which is stereo, and the disc player obliges. Check the AUDIO OUT flag, which forces the mixed EDID to present the maximum audio capabilities of the sink at the audio output, or 7.1 Full to force full sound outright. Over RS232 or IP the same choice is set edid audio full. In CUSTOM mode, pick a table whose name ends in All Sound rather than SPDIF or Stereo.

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