Its DD or DD+ stereo-only (2.0 channels), thus "DD2.0" or "DD+2.0" as opposed to say "DD5.1" or "DD+5.1" - this is common in TVs (E.g. LG) that have built-in DD+ decoders/encoders/transcoders and built-in apps - instead of outputting PCM 2.0 they can/do/sometimes output DD/DD+2.0 (depending on the detected ARC/eARC device and app) instead.
A little reading on the subject...
What distinguished DD 2.0 from just regular PCM stereo (other than file compression) is that with DD 2.0, you could possibly get matrixed audio on those two channels. In other words, 4 channels of audio could be decoded out of two discrete channels of data. This is what Dolby Pro Logic (and its later variations) provided - a rudimentary surround experience. Dolby Digital, Dolby Digital Plus, et al., provide actual separate discrete channels of audio.
Here's how a Dolby Surround book defines 2.0:
"Dolby’s ability to encode and decode information is only as strong as its source data. If it’s working with a two-channel stereo movie, you may see something like “Dolby Digital 2.0” on the package, designating that it is a stereo signal being encoded and decoded using Dolby Digital. All fine and dandy, but it’s still a stereo signal. However, if your receiver includes Dolby Pro Logic, Dolby Pro Logic II, or even Dolby Pro Logic IIx, the stereo signal on the disc can still be listened to as a multichannel surround signal, thereby allowing you to achieve full playback on your system."
The idea of the poster being that at the time of upload to YT the 5.1 audio is surround matrix encoded (Lt/Rt) in 2.0 and then transcoded to AAC-LC (Stereo+5.1) (which is what YT uses) and then, at playback, depending on the device/app capabilities (e.g. Roku 4640), the AAC-LC (Stereo+5.1) encoded is then transcoded back to DD5.1 (or DD2.0) or DD+5.1 (or DD+2.0) with the Dolby decoder/encoder in the 4640 for output via Optical/HDMI.
(This is what my LG TV does in fact with (some of) the internal apps - 2.0 AAC/PCM is transcoded to DD2.0/DD+2.0 when output.)
THE NICE PEOPLE AT ROKU DON'T TELL US ANYTHING! I FINALLY DISCOVERED THAT DOLBY DIGITAL WILL ONLY WORK ON "CERTAIN "MOVIES ONLY ON THE R O K U CHANNEL... THAT IS SO STUPID. THANK YOU R O K U
DD+ is simply built on top of Dolby Digital 5.1. It’s was designed so that even if using receiver that does not support DD+, it will output Dolby Digital 5.1. You can think of DD+ as working on top of the Dolby Digital format allowing variable bitrate. Essentially if you have something that works with DD+ It will work with/in Dolby Digital 5.1.
Actually... you could think of Dolby Digital plus as a suitcase.
That carries ALL forms of Dolby digital. Their own standard is that it has to. Dolby Digital carried 5 separate bandwidths channels
DD+ carries 15.
So it carries the previous Stereo, 5.1, and the newer 7.1/ HD/ Atmos. It essentially carries all Dolby has produced that is still in use today. And HD DVD (basically obsolete) and Blu Ray HAVE to use DD+, in addition to whether they decode DTS or whatever else, or not.
So it only makes sense Netflix and Prime and other streaming services utilize it. Dolby is the industry standard.
As far as I know, Roku doesn't encode or decode, maybe the newest ones might, I don't know. Mine's a few years old. Far as I know it acts as a pass through.
I have a 4K UHD/ HDR TV and the 4k Roku Ultra. But hooked up to an 18 year old Denon receiver. And it outputs 5.1 perfectly fine.
It's a matter of the HDMI connect from the Roku to the TV and then the Digital Optical connect from the TV to the receiver.
They seem to be important in sending the proper signal for the receiver to be able to decode and output the best possible audio.
Because the cable box does the same. Connects via HDMI to the TV and the TV to receiver.
The Roku and TV both acting as passthrough. The source of the DD+ signal being the streaming service via internet, or cable channels via internet/ cable.
In my case, best I can hope for is Dolby Digital 5.1.
Or in some cases PCM or DTS depending on source. But I was also pretty diligent about the receiver I got, because I was into collecting 5.1 audio when it was a short lived fad through DVD-A/ DTS or SACD. So I made sure I had a receiver (and HD CD/ DVD player) that could play all those variables successfully.
Earlier in this thread, I forget the user's name, but he was the one that pointed out that it was the audio settings in the Roku itself that were misleading. And his suggestions were spot on about how to tell the Roku to properly act as the optimum pass through to deliver surround sound to legacy equipment.
My understanding, is, though, that if you're not delivering the audio to your legacy receiver with an HDMI/ SPIDF Digital Optical, then you'll have trouble and may end up with only stereo only or a Pro Logic default. I'm not sure about Digital Coaxial connections. And I may be wrong about other potential connections. But I know what I have the way I've described and the Roku audio settings as earlier described elsewhere in the thread, have worked without issue for me.
Also, TV audio settings should be checked also to allow pass through ability. That should go without saying. But when we're troubleshooting, it is far too easy to overlook the most obvious things.
But ultimately, and to the point, when I read up on Dolby Digital Plus, the analogy of a suitcase popped into my mind.
In reply to Heyitsrick, I pulled my console out over the weekend and wiggled my connection for my Blu-Ray player to make sure it was connected properly to my A/V receiver and now it works fine, and my switching does work on my A/V receiver. I then connected my Roku player directly to the A/V receiver as you recommended (note that Roku is not very friendly with providing a HDMI cable that is only 2', it would have been nice if it was 4' as I had to stick it on the side of my DVR way in the back, luckily it is small enough to do so and the remote control has a IR blaster to reach it). I found that the Roku does pass the DD+ to my receiver and it decodes it on Prime Video and I do get the 5.1 surround. The Roku channel works fine in Dolby Digital. (A side note with the Dolby Digital Plus, I get some minor static on the speakers when I do a rewind, it is very short. Do you get that?)
I have also found that the ARC control in both my Receiver and TV will pass the audio to the TV speakers when in stand by mode on the receiver but the TV will not play audio for the Dolby Digital Plus, it just goes silent and video plays. I also tried the Blu-Ray player as well and it will play on the TV speakers as I found that it is supported by Dolby Digital, so even though my TV states it supports DD+ it doesn't seem to. ?
I found that that ARC Control on my TV will automatically turn on my A/V receiver when it is turned on and if I want to use the TV speakers I just turn off the A/V receiver and the audio will transfer to the TV speakers and the blue light you referred to is on. I was not aware of Control with ARC and how it worked when I originally set up my system and just stumbled into it when I added the Roku and was trying to figure out why I was only getting stereo from the Amazon Video.
Thanks for your help.
I understand, and I after months of myself making an honest and diligent effort to contact them, they never once replied. This Dolby Digital issue is real, but I finally discovered what the problems are.
Imagine, although they have the ability to pass through "ALL" DOLBY DIGITAL, for whatever reason(s) they don't. I'm guessing it's because they don't want to pay not a penny more to DOLBY for such licensing.
Dolby Digital will work, but only on certain DD encoded movies on their ROKU CHANNEL only. Yes, you heard that right, on the ROKU CHANNEL, and no where else!
All they had to do is "SIMPLY" advise their customers of this, and it would of saved everyone a great deal of aggravation. Apparently they could care less.
This will undoubtedly reduce their sales to Audiophiles that prefer Dolby Digital over AAC...
Try the ROKU Channel, and when you stream certain movies, VIOLA, your Dolby Indicator light will appear. The sound quality is excellent, but it should be for all channels including XFINITY but it isn't. I called Xfinity for help quite some time ago, but they too could of cared less for what ROKU is delivering to their customers. So sad.
When 5G is available, and multitudes leave Xfinity, they have no one to blame but themselves. But at an income of $200 billion a year, I don't think Xfinity cares either.
Just my opinion.... TRY THE ROKU CHANNEL (MOVIES) and see for yourselves like I did!