But as it supports Atmos via LPCM, it won't really matter... unless your TV:
- doesn't have eARC
- can't decode & convert other formats to LPCM 7.1/Atmos LPCM 7.1
- can't pass through LPCM 7.1/Atmos LPCM 7.1
Technically, it does matter.
Although Linear PCM will be the cleanest audio, you still need support for codecs which matter such as Dolby Digital Plus. Dolby Digital has only been left on the soundbar as a way to gain surround sound through the optical connection. But DTS and other 7.1 solutions can be reencoded as LPCM 7.1 which is why they were dropped.(..)
The only way around this is to use a source device such as the Apple TV which can take the audio directly from the streaming app and present it in Dolby MAT which is technically Linear PCM 7.1 with Atmos metadata, just wrapped in a Dolby Atmos format.
I mentioned that in my second point as you would need to have that external device (like a 4K UHD/Bluray player) decode Atmos Dolby Digital Plus into LPCM.
The problem with Dolby Digital Plus Atmos is you can't change it to a Linear PCM format. You can reencode Dolby Digital Plus, but not when it has Atmos metadata. (..)
As far as I'm aware, no other streaming device does this such as the Amazon Fire TV or Roku as they all use Dolby Digital Plus and if your TV can reencode audio as a Linear PCM 7.1 format, it won't do it for Dolby Digital Plus with Atmos.
Can you share your sources on this?
That's my point exactly, which is where you're making a mistake. Linear PCM does not support Dolby Atmos, which means you can't reencode Dolby Digital Plus with Atmos into a Linear PCM format using a Blu-Ray or your TV. It's static and fixed.
If you've got a few days to spare, you can read all of this on the Dolby Developer website, but I will break it down for you to know the significant bits. I know all of this because I work in audio.
Dolby Atmos is metadata, not a codec which means it can lay on top of any audio signal as long as you can wrap it correctly in the audio codec such as Dolby Digital Plus or Dolby TrueHD. Unfortunately, Atmos can not exist on its own, so Linear PCM can't support it as it only has eight channels of analogue audio. So there is no stream for metadata.
Streaming Services or TV channels such as Netflix or Disney use Dolby Digital Plus as the bandwidth is much smaller at 768kbps when you compare it to Dolby Digital at a maximum of 640kbps. Therefore, it has no real impact on the service or the user to add that small amount of data.
Dolby TrueHD is mainly Blu-Ray only because the bandwidth with Dolby Atmos can range up to 18000kbps depending on how lossless the audio is. Although we're in 2021 and most internet connections are hitting gigabit speeds, services would realistically not handle an extra 16mbps of internet connection on top of a 4K stream which is usually around 25mbps. It's half of another 4K stream and costs money.
Dolby invented MAT mainly for gaming on PC. It's a way to place the Dolby Atmos metadata on top of the Linear PCM analogue audio. So it's Linear PCM with Dolby Atmos but wrapped in Dolby MAT, which allows it to travel together to a receiver. The Xbox One and Series X|S now support this, and Apple TV does too.
I believe Apple TV gets around this by having the streaming service offer the Dolby Digital audio and Atmos metadata separately, which allows them to decode the Dolby Digital audio into Linear PCM and then pack it into Dolby MAT with the Atmos metadata. Why they do this over just supporting Dolby Digital Plus is beyond me, but Apple TV has always been Pro-Linear PCM and prefers to output this over using compressed formats.
Any receiver that supports Linear PCM and Dolby Atmos should automatically support Dolby MAT. Because of this, many older receivers will show LPCM or LPCM/Atmos on them instead of Dolby MAT.
- A Blu-Ray player can reencode 5.1 and 7.1 formats such as Dolby Digital, Dolby Digital Plus, Dolby TrueHD to Linear PCM 5.1/7.1.
- Dolby Atmos is metadata that has to be wrapped in Dolby Digital Plus or Dolby TrueHD.
- If you want to use Linear PCM with Dolby Atmos, it must be wrapped in Dolby MAT by the source device. Only a PC, Xbox, or Apple TV supports this.