Is it correct to say that the Apple TV 4K takes DD+ stream for Dolby Atmos from a service eg Netflix, decodes it in the box and sends it to eg. a AVR as a Multi- In PCM stream?
Other media boxes have a bitstream option which allows the AVR to do the decoding.
I am curious if any one can tell me what is the reason the Apple TV 4K makes this choice?
Is it correct to say that the Apple TV 4K takes DD+ stream for Dolby Atmos from a service eg Netflix, decodes it in the box and sends it to eg. a AVR as a Multi- In PCM stream?
Yes, sort of. It outputs Atmos in Dolby MAT format, which is uncompressed like PCM, and may be identified by some receivers as Multichannel PCM. Technically Dolby MAT includes the spatially encoded meta data added to the multichannel data stream, i.e. not discreet channels, but the intended object based audio, to be rendered by the receiver/audio system. Sending the audio uncompressed means no quality difference with AVR decoding. HDMI devices are supposed to do this (mandatory fixed bitrate uncompressed for Dolby Atmos).
Dolby Atmos for the Home Theater - Dolby Laboratories [PDF]
Home theater implementation - Dolby Atmos - Wikipedia
I am curious if any one can tell me what is the reason the Apple TV 4K makes this choice?
Apple hasn’t said. And we shouldn’t speculate here.
Urquhart1244 wrote:
[...]
Dolby Atmos for the Home Theater - Dolby Laboratories [PDF]
Home theater implementation - Dolby Atmos - Wikipedia
Another good reference is Nakamichi's "Ultimate Dolby Atmos Guide". It references their products in examples but evenhandedly -- it's an educational piece.
am curious if any one can tell me what is the reason the Apple TV 4K makes this choice?
Apple hasn’t said. And we shouldn’t speculate here.
One not-so-speculative reason for the Atmos decoding (if not the Dolby MAT encoding) is to support spatial audio with dynamic head tracking using various models of AirPods and Beats headphones (more speculative: probably also the 2018 HomePods support as well). Although as @lkrupp points out, the ATV audio decoding approach predates these spatial audio innovations.
Since the original release of the Apple TV users have been asking this question. Many have asked for/demanded the option but no responses from Apple and no explanation as to why the the Apple TV does its own thing with audio decoding.
Hi Urquhart1244
Thx for taking the time to write your articulate and informative reply.
I found a quote in the Dolby Document.
" A key benefit of Dolby MAT 2.0 is that Dolby Atmos object-based audio can be live encoded and transmitted from a source device with limited latency and processing complexity. Among the possible sources are broadcast set-top boxes, PCs, and game consoles. The Dolby MAT 2.0 decoder in an AVR outputs the object-based audio and its metadata for further processing. The Dolby MAT 2.0 container is scalable and leverages the full potential of the HDMI audio pipeline. "
On the other hand most devices provide the option of bitstreaming.
Verrrrrrrry Interesting! 🤔
Cheers 🍻 🦊
Hi Ikrupp.
Thx for your reply. 👍
Curious isn't it, as wouldn't it be cheaper for Apple not to implement a Dolby Atmos MAT encoder in their device.
Still Apple aren't silly and must have a good reason.
Cheers 🍻🦊
What is the advantage of decoding audio in the Apple TV box and not having a bitstream option?
