No Dolby or DTS Surround Sound Output Via Optical on Roku Streaming Stick 4K (2021)
I just bought a Roku Streaming Stick 4K (2021) connected directly to my LG OLED65E6P from 2016. My TV is connected to my receiver via optical cable. Through this cable, I am able to enjoy Dolby and DTS surround sound from the LG native apps (Netflix, Disney+, Vudu, etc.) as well as from my Blu-ray and DVD player connected to the TV via HDMI.
My new Roku Streaming Stick 4K is also connected directly via HDMI, but it will only output PCM stereo no matter what the setting. Right now, the audio output on the Roku is set to "Auto," but I have tried every combination to try to force the stick to output surround sound to the TV for pass-through to optical out, but nothing works. My older Roku model is able to output to the TV and pass-through surround sound via optical with no problem (as well as the devices/apps I mentioned earlier), but this new stick only outputs PCM stereo.
Does anyone know how to force the Roku Streaming Stick 4K to output 5.1 surround sound via HDMI for pass-through to the TV to optical to the receiver? This is extremely disappointing and makes me want to try another streaming device.
DD+ (EAC3) has been around for nearly 20 years, and superceded DD (AC3) 10-15 years ago. The DD+ bitstream is not inherently backwards compatible with DD, though devices with DD+ decoders can transcode/convert DD+ to DD for output (with limitations, depending on device).
Most streaming services/apps (e.g. NetFlix/Prime/Disney+/Hulu) use DD+ (EAC3) exclusively (other than AAC 2.0 converted to PCM 2.0 on device), so in order for DD (AC3) to be passed via Optical (Optical only officially supports DD, not DD+) either the streaming device or the device it connects to (AVR/TV - TV in your case) has to be able to transcode/convert DD+ to DD from HDMI>Optical (this requires a Dolby decoder).
However, from your description your TV cannot (or is not currently configured) to do this, though it doesnt explain "your older Roku", unless its a model 4640 (2016 Ultra - it has a Dolby decoder, like the new 2020/2022 Ultra - model 4800/4802).
There are some streaming services/apps (e.g. YT/YTTV/HBOMax/Paramount+/Apple TV/The Roku Channel) which can either do both DD+ and DD or only DD (depending on device detection/configuration), in which case as long as a device can passthrough DD from HDMI to Optical you will be able to experience their content in 5.1.
If Settings/Audio/Digital output format = Auto and "formats detected" = DD (not DD+) then your TV does not support DD+ passthrough from HDMI (just DD), in which case most/much streaming content will only be in PCM 2.0 (aside from the services/apps listed above), since the SS4K has no Dolby decoder (transcodes/converts DD+ to DD), and your TV doesnt support transcoding/converting DD+ from HDMI to DD for Optical.
Assuming you want to keep your TV and AVR, your best solution would be to get a model with a Dolby decoder, such as the Ultra 2022 (4802) or Ultra 2020 (4800), which can trasnscode/convert DD+ to DD for output via HDMI and allow Dolby 5.1 from all streaming services (regardless if they use DD+ or DD).
I recommend returning the SS 4K/4K+ and obtaining the Ultra 2022 (4802) instead for your situation.
Otherwise, many competitors' products have Dolby decoders, including the FS4K/FS4KMax, TS4K, O4KSB, and NS (the GCCWGTV does passthrough only like the SS 4K/4K+ so you want to avoid it).
FYI, there is an even newer Dolby codec intended to supplant DD/DD+ (AC3/EAC3) - AC4 (no known trade/brand name yet), and it is supported in some products, including the 4800/4802.
