Originally Posted by HockeyoAJB
...my concern isn't with the streaming services capabilities or the internet bandwidth but with the ability of current streaming devices (Roku, AppleTV, smart TV, etc.) to recognize that the connected AVR is capable of decoding a Dolby Atmos soundtrack and then tell the streaming provider to send it the Dolby Atmos soundtrack rather than the plain old DD 5.1 version.
Ah, got it. I'm guessing that Atmos soundtracks for home video will have a core + extension structure, for backwards compatibility. The core will be a 5.1 or 7.1 channel-based mix containing all the sounds. The extension packet will have the objects.
Older AVRs won't recognize the extension packet and just play back the channel-based core. Newer, object-aware AVRs will decode the objects, slice those sounds out of the channel-based mix, and render those sounds where intended.
Since Atmos mixes are a collection of sounds, in channels and as objects, they can be compressed like any audio is. For streaming, the audio will be compressed using DD or DD+ (more likely the latter). Your Roku will see a DD+ stream, like it does now, and pass it on to your AVR.
Your current AVR will decode the DD+ 5.1 mix. If you get one of the newer AVRs, it will decode the entire Atmos soundtrack.
The Roku has no idea what's in the bitstream; it just recognizes the DD or DD+ flag and passes the data through. It has no idea whether your AVR will decode only the channel-based core or fully decode the core+extension Atmos mix.
Same with my 7 year old BD player. It will see a TrueHD bitstream and pass it through, like it always does. It will have no idea that there is an Atmos soundtrack inside that TrueHD wrapper.