"The base horizontal layer uses 5.1 or 7.1 format, the height layer is on top of the base layer and its information is extracted from the standard 5.1 surround PCM carrier."
WTF is "the standard 5.1 surround PCM carrier"? DD is a
lossy compressed format, not
PCM.
There are several technologies here to unpack and not confuse, as those would works differently with Auro 3D.
1. Dolby Digital (5.1) and Dolby Digital Plus (7.1 and more) on their own - compressed audio, discrete channels
2. old Dolby Surround over PCM - stereo, uncompressed audio, with matrix surround, e.g. Pro Logic iterations
3. new Dolby Surround - replacement for Pro Logic; upmixes stereo and surround to play on Atmos configs
Auro 3D
The original text reads: "Auro-3D is an immersive 3D audio format developed by the Belgium-based company Auro Technologies. It consists of three layers of sound - surround, height and overhead ceiling. The base horizontal layer uses 5.1 or 7.1 format, the
height layer is on top of the base layer and its information is extracted from the standard 5.1 surround PCM carrier. The a/v receiver decoder then extracts this information during playback."
This makes sense in principle. In order to create Auro 3D sound field, AVR's algorithm could use PCM stereo signal or LPCM signal with descrete 5.1/7.1 channels and any metadata for heights and overherad. It's debatable how much could Auro 3D make listening a pleasant benefit from PCM with matrix surround over traditional speaker layout. Try at home and let us know. "Standard 5.1 surround PCM carrier" is unfortunate expression here, but we should see it as explained below.
PCM - uncompressed stereo
PCM can carry plain stereo and also older Dolby Surround/DPL, which is 2-channel stereo with the center and surround channels mixed in, so it will play as stereo or surround. This is an old school 5-channel set-up. Modern AVR or soundbar should be able to decode this and send it to the right places on the system. Everyone can play PCM stereo or PCM stereo with embeded Dolby Surround on 2, 5 or 7 speakers.
For Auro 3D, the question is once 5.1 Dolby Surround from PCM stereo signal is mapped on the base 5.1 layer, is there any different sound left to be heard from the heights? No. The heights could simply repeat what is already on the base layer if the output is set over 5.1 + 2 high speakers, the same as playing 5.1 track over 7.1 speakers.
Another example. PCM from a TV is almost always plain stereo or stereo with Dolby Surround (not to be confused with Dolby Digital). Most of the older non-HD core TV channels use Dolby Surround because the signal carries a hidden centre and rear surround field that is ignored by basic stereo-only capable gear. Soundbar or AVR would detect the hidden Dolby Surround and activate its Dolby ProLogic decoder (DPL or DPLII) and you might have the option of setting it to DPL II Movie/Music/Game.
