HDfury Diva

Audio

Audio extraction

Splitting sound out of an HDMI stream

In short

Taking the audio out of an HDMI stream and delivering it on a separate output, so a receiver can hear it without having to handle the video.

HDMI carries picture and sound in one cable, which is convenient until the box that should decode the sound cannot cope with the picture. Extraction is how the Diva separates the two.

HDMI carries video and audio together in the same stream. That becomes a problem the moment the two need to go to different places, or when the device that should decode the sound is older than the device that should show the picture. An audio extractor splits the sound out and presents it on an output of its own.

The usual reason is a receiver that cannot pass the video. An amplifier bought before HDCP 2.2 or before 18Gbps becomes the bottleneck of an entire chain if the signal has to travel through it. Extracting the sound and sending the picture straight to the display keeps the receiver in the system as a decoder and an amplifier without letting it limit anything.

Extraction is not conversion. A well-behaved extractor passes audio on in the form it arrived, so the limits are those of the output you take it from: an optical link cannot carry a lossless bitstream no matter what is fed into it.

The three audio outputs of the HDfury Diva

HDMI audio output
A self-generated 720p or 1080p video stream carrying full audio, made to feed any AVR input. The sound can come from any source at the Diva inputs, or from eARC or ARC on TX0. Use this when you want every format your amplifier can decode.
TX1
Equipment that is only capable of 1080p, in HDR or SDR, connects here and gets full HDMI sound and video. Make sure the EDID presented to the sources reflects that equipment's audio capabilities, or a source will send something it cannot decode.
SPDIF or L/R analog out
One 3.5mm combo jack carrying either analogue left and right stereo or optical S/PDIF up to 5.1, using the supplied jack optical cable. It can also carry ARC audio taken from TX0.

Sound pulled back from a television is extracted the same way. With an eARC capable TV on TX0, up to Dolby Atmos HBR over TrueHD is extracted and forwarded to the HDMI audio output automatically, with no CEC option to set. With an ARC television the Diva handles up to DD+ and Atmos over DD+, which you can route to the HDMI audio output, to the optical output, or to both.

Settings that shape the extracted sound

MUTE TX0 AUDIO
In the CONFIG section, silences the sound going out of TX0, which you want when the amplifier is fed from the HDMI audio output and the display should stay quiet. The command is set mutetx0audio on.
MUTE TX1 AUDIO
The same for the TX1 output, with set mutetx1audio on.
ANALOG L/R AUDIO CONTROL
Volume, bass and treble for the analogue stereo output, applied when you click SEND. The commands are set analogvolume, set analogbass and set analogtreble, with volume running from -30 to +10 dB.

Related terms

S/PDIFA two channel digital audio interface, on optical or coaxial cable, which can also carry a compressed multichannel bitstream.ARCThe HDMI feature that sends sound backwards along the cable, from a television to an amplifier or a soundbar.eARCEnhanced Audio Return Channel: the link that sends sound backwards along an HDMI cable from a television to an amplifier, with room for lossless formats.BitstreamSending compressed audio onward in its original encoded form, so the receiving device rather than the source does the decoding.AVRAn audio/video receiver: the box that decodes surround formats, switches sources and drives the speakers in a home cinema.

In the manual

The pages of the HDfury Diva manual where this comes up.

All glossary terms