I'm a couple weeks into my research, and Blu-ray Disc ripping, and have collected some good information. I'm sure this information is nothing new to the savvy multichannel enthusiasts in this community, but based on my conversations with many others, there are tons of music lovers who are interested in Atmos and eager to learn.
I continue to be surprised at how Wild West this area of music playback remains, years after its release. The more I learn, the more parallels to computer audio I see. For example, trying to get decoded Atmos audio out of a computer ranges from simple (Dolby Digital Plus) to impossible (Dolby TrueHD). Searching for ways to achieve the impossible, as many of us like to do, leads to a few possibilities but after chasing them down and twisting the possible solutions into a logical pretzel, they are dead ends.
Dolby has so tightly controlled TrueHD decoding on computers that it doesn't make sense for me to continue pursuing the path. I could probably get something to work with a professional digital audio workstation, but even with that there are no guarantees because of the file formats required. In addition, it doesn't interest me too much to find a solution that works only for me and maybe a couple people willing to use kludgy audio systems. I remain optimistic that someone will find a solution to this issue.
The bottom line is if people want to play lossless TrueHD, they have to use HDMI and an Atmos processor. Don't get me started with vaporware products promising HDMI to AES67 conversion (Arvus). The reason why I touch on this HDMI thing because there are other possible solutions for Atmos playback, that don't involve a traditional processor with HDMI input. I will get into those in update 2.
Note: There is no industry accepted source of TrueHD content on a computer, so there is no solution to play this content. All such content is from ripped Blu-rays at the moment, and we know how the industry views ripped Blu-ray Discs.
I found out from Trinnov why my Apple Music streams were output as 7.1.4 but not my TrueHD rips being played back on the same Mac. Because macOS only supports Dolby Digital Plus, it isn't a native TrueHD decoder. TrueHD content will then be sent out as basic TrueHD, without height channels in the Atmos metadata. I knew about the DD+ issue on Mac, but could figure out why the Mac would play TrueHD content as 7.1. Now I know.
Much of my research right now surrounds processors for decoding Atmos. I've talk to people in the industry and manufacturers about the differences, and they are pretty large. The big ones for me are the difference between software and hardware decoding, room correction, and upgradability. Almost all processors use a mass produced chip to decode Atmos audio. This isn't bad in and of itself, it's just the mainstream way of decoding. Other processors handle decoding in software. These are endlessly flexible, upgradable, and appear to be capable of processing more channels at higher sample rates. Software based processors typically use a computer running Linux, so they run like an appliance. The end user doesn't interact at all with the operating system.
Some processors I'm focusing on today are from Trinnov, Datasat, Lyngdorf, and the new McIntosh MX180 has be intrigued. As always, I love the recommendations people are sending me. I'm all for whatever works for each listener, and very interested in all ways of doing this.
A couple things I really want in a processor are the ability to know which speakers are receiving / playing the audio signal, and identification of the incoming stream as lossless TrueHD or lossy Dolby Digital Plus. I know Trinnov can show much of this, can solo a single channel to hear the output, and can even show an object based view in real time. But, one hiccup is that the Trinnov processors identify all incoming Apple TV streams as lossless TrueHD, when they are really lossy DD+. I'm unsure what would happen if I connected my Mac Mini (M1) via HDMI and bit streamed the content from Kodi, but I believe it will show correctly.
Note: Newbies should understand that creating an Atmos mix involves the engineer placing sounds wherever s/he wants in space, not in specific channels like the old days. These sounds are the objects everyone talks about when Atmos is referenced. For example, a vocal can be placed front and center, without regard to number and placement of channels in a listeners home or headphones. Originally the core or bed channels were to be the 7 (or so) at ear level and the objects based audio as to be the height channels. In reality, mixing engineers are using object based placement for everything, except the LFE channel which remains really the only bed / core channel.
Getting back to HDMI input for a second. HDMI is required for the Atmos heigh channels to work for lossless TrueHD. I can get them to work over Ravenna / AES67 with a Merging Technologies device, but this only for lossy DD+. Atmos audio coming into a processor over HDMI also contains metadata that directs sound to the height channels. This is a bit different for audiophiles because a 7.1 stream can be decoded to 7.1.4, with 8 channels of data plus metadata. Ripping Atmos music from a Blu-ray Disc one can see Atmos TrueHD 7.1 channels, but if used by the mixing engineer, it will play as 7.1.4. This is partially why FLAC, with its limit of 8 channels, doesn't work for Atmos playback. MKA, M4A, and MKV files work best.
I have emails into Tidal, Dolby, and others about some of this stuff. I really want to know if Tidal is going to enable Atmos playback on the desktop.
Last, when texting with a recording engineer friend of mine, he asked if I though if people would really install 12 speakers in their homes for Atmos playback. Thinking about this further, I realized the install base for Atmos capable playback is already exponentially higher than high end two channel. Yes, some of these systems are Atmos soundbars, but it may be an entry into higher fidelity for some people. Everyone starts somewhere. As for us audiophiles, if out goal is to playback music as the artist intended, Atmos is required for a 7.1.4 mix. Doing this at the highest level we can, within space and budget constraints, is what audiophiles are all about.
Given that the vast majority of my music is two channel, that's how I'll be listening the vast majority of the time. Remember, I'm a card carrying, knuckle dragging, audiophile with zero intentions of abandoning two channel. I don't yet see a high end path for my two systems to use the same processor. However, because I'm using Constellation Audio amplifiers for my front two channels, I can flip a switch on the back to from a high end two channel to multi channel system very easily. It's the only way to get ultimate fidelity with DACs from dCS, EMM Labs, etc... Atmos is supplemental for me.
That wraps update 1 in my Immersive Audiophile series. In update 2, I'll cover my research into NOT using a traditional processor and saving many thousands of dollars. Keep the comments, questions, and information coming!
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