01-Apr-2022, 08:43
(01-Apr-2022, 06:47)Drifter Wrote: Dolby Labs developed an algorithm that is able to allow audio producers to record multi channel information into a standard audio recording. In order to decode the multi channel information one requires the use of a decoder. AV receivers (Denon, Yamaha, Marantz etc) have this decoder as part of their circuits. It all started with Dolby Digital with allowed for the recording of 5.1 channels and have since evolved to Dolby Atmos which allows up to 9.1.4 channels. Dolby Atmos is object based which basically just means that in addition to the front and surround speakers, over head speakers are added and in the 9.1.4 Atmos terminology the ".4" refers to the number of overhead speakers.
So for Dolby Digital or Dolby Atmos to work the source audio requires that the multi channel info was recorded into the audio stream by the producer. Dolby also has a decoder that is able to take standard two channel audio and, using fancy algorithms, split the two channel audio stream into multi channels. This is called Dolby Surround and it is able to split the audio stream even into over head channels. So you can get the same effects from Dolby Surround as from Dolby Atmos. It is surprisingly effective.
In order to use the various Dolby decoders that Dolby Labs have created, one needs to pay Dolby Labs. It would appear as if the Dione does include the Dolby Atmos decoder. HOWEVER, it does not include the Dolby Surround decoder. The way that I understand Devialet's "SPACE is that they effectively wrote their own version of the Dolby Surround that is able to take a standard two channel signal and splits it into 5.1.2 (which is the number of speakers the Dione has) channels.
This has nothing to do with SPATIAL AUDIO from Apple which is headphone audio reproduction system as Struts correctly explained in his OP. Devialet uses the terms "spatialized" which is where the confusion comes in. It has nothing to do with Apple SPATIAL AUDIO but is simply the word that they chose to describe how "SPACE takes a standard two channel audio stream and "upmixes" it into 5.1.2 multi channel audio - exactly what Dolby Surround does.
The Dione does not support Apple SPATIAL AUDIO as it is for headphones and irrelevant to scenarios using fixed position speakers with a listener whose head is facing the front all the time.
Further, Airplay2 does support the transfer of Dolby Atmos signals over its protocol, so in theory you should be able to get the Dione to decode Atmos from an Apple TV that is not directly connected to the Dione via HDMI but is streamed wirelessly using Airplay2.
Hi @Drifter
Many thanks for filling in the background on Dolby, certainly is a lot to learn here!
I am still a bit confused as to whether Dolby Surround used metadata embedded in the stereo signal or not. Reading the Wikipedia entry for Dolby Surround (below), the statement that it decodes Dolby Stereo 4-channel soundtracks kinda implies that it does. If it doesn't then I can only assume that its effect is fairly limited. Deriving a centre channel from L and R is not rocket science but deriving directional information from data that contain no directional information is.
Quote:Dolby Surround]
Dolby Surround is the earliest consumer version of Dolby's surround sound decoding technology. It was introduced to the public in 1982 during the time home video recording formats (such as Betamax and VHS) were introducing Stereo and HiFi capability. The name Dolby Surround described the consumer passive matrix decoding technology; the professional, active-matrix cinema technology bore the name Dolby Stereo. It was capable of decoding Dolby Stereo 4-channel soundtracks to 3 output channels (Left, Right, Surround). The Center channel was fed equally to the Left and Right speakers. The Surround channel was limited to a 100 Hz to 7 kHz frequency bandwidth, as dialog from the center channel could leak into the surround channel - there was as little as 3 dB of separation between LCR and Surround channels.[1
The glib and hyperbolic description of SPACE™ clearly states that 5.1.2 information can be derived from "any mono or stereo signal", i.e. no metadata. If that were true then I would expect Devialet to have patented it and for that patent to be one of their most valuable assets. It is possible to create anything resembling spatial audio out of a rip of a 78rpm mono recording? Show me! There's a big difference between "there's something going on above/behind me" and "defined sound sources moving in 3D space above/behind me".
To your last point, yes, Airplay 2 is quite capable of transporting Atmos signals and indeed it does already (see my second post, above). However the way Apple has implemented Atmos support requires that the Apple TV and the relevant speakers be assigned to the same room in the Home app which requires the speakers to support HomeKit (they need a HomeKit Setup Code to identify them) which Dione currently does not. As I said above Apple currently seem to be confining Atmos-over-Airplay to one or two HomePods or HomePod minis although it is unclear if that is for technical or commercial reasons. Also, since there is currently no way of assigning speakers in Airplay 2 to receive different channels of the same track other than as a simple stereo pair the only Atmos modes currently supported are 1.0.0 and 2.0.0.
