ok, firstly apologies if I used the wrong tone last night. I started by using the same form of words as JeffChap, thinking it would be a "fun" way of adding the information, but perhaps in hindsight it wasn't.
Genuinely surprised that this is news to people. Perhaps it is the fact that ARC is so difficult to get working, that comparitively few of us are in this situation?
However I'm at work at the moment and I can't do tests, and I feel I am in danger of conflating several different things:
- LG TVs being "awkward" with ARC in general
- I initially used Optical for my "TV audio output" because of this (and I'm sure I had DD+ working ok)
- But then Jack Ryan was released, and I wanted DV and DA together, so I tried extra hard to get ARC working
- I succeeded, and I got Atmos-inside-DD+ fully working over ARC-in-HDMI.
- I believe, with the LG TVs, this is the only way to get (lossy) Atmos out of the internal apps, and this is DD+, and of course this is nothing new (to me)
- My memory is that if you use Optical for your "TV audio output", you don't get Atmos but instead it "falls back" to DD+. With non-LG TVs, there's no DD+ over optical and you just get 1990's lossy DD.
I promise to test this tonight, but given the incredulousness from last night a) I'm now doubting myself!, and b) not sure what level of proof would help
. A better photo of the front panel of the AVR is probably the best I could offer for now..
In the meantime, here are some links and refs I found quickly.
IEC 61937-3: defines how to transmit Dolby Digital (AC-3) and Dolby Digital Plus (E-AC-3) bitstreams via an IEC 60958/61937 (S/PDIF) interface. However, the S/PDIF interface has insufficient bandwidth to transport Dolby Digital Plus (E-AC-3) bitstreams at the 3.0Mbit/s datarate specified by HD DVD; lower datarates are possible.
Netflix and Amazon Prime both do use those "lower datarates", so it works (from my recollection).
That wiki page also goes on to say that with some equipment which do not recognise the DD+ bitstream, it is in danger of getting corrupted during transport. It's not implemented by many TV manufacturers.
But, it is by LG.
post by "snapilica2003" [Onkyo SR608 AVR]
Firstly, the official spec of ARC (basically S/PDIF over HDMI) does not allow DD+. The spec was established before DD+ was even a thing. Only 5.1 DD and 5.1 DTS are supported. Now, technically, even though it's not in the spec, E-AC3 can be sent through ARC, as long as the bitrate is at or bellow 640kbps (the max bitrate allowed for standard 5.1 DD). And Netflix DD+ streams are under 640kbps so it should work.
post by "Djuganight" - he's having ARC-in-HDMI propblems, which meant his last sentence is actually the most helpful:
I have a LG OLED55C8 and the internal neltflix app only plays sound over HDMI ARC if I have the TV set to PCM. If I put on Automatic I only get crackling noise. If I connect via Optical Audio Cable all works well and netflix sound is output as DD+
That's the best I can find from here for now, HTH.