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Multi-channel Audio Part 2

by kogir on 2/2/24, 6:49 PM with 32 comments

• by adanto6840 on 2/2/24, 8:03 PM

  Somewhat tangential, but here's a cool somewhat open-source project related to Dolby Atmos:

  https://cavern.sbence.hu/cavern/

  https://github.com/VoidXH/Cavern

  The visualizer, which is what I was _most_ interested in (along with software decoding) is written in C# and the rendering is done in Unity -- both things I valued & thought were cool. In theory, you could build a DIY multi-channel "receiver" with this type of software if given enough audio outputs (and/or put something like Dante to use).

  I explored it a bit further but it's relatively cost prohibitive, especially if you want to do something like accept HDMI input, it gets messy. AFAICT, at least when I went down this research path a few months back, even finding & getting dev kits/boards with HDMI input (of semi-recent generation) was non-trivial & pretty pricey.

• by omnicognate on 2/3/24, 8:27 AM

  Atmos has put me in an awkward position. I have a proper home cinema setup (AVR, wired separate speakers including the ones that bounce sound off the ceiling) and listening to Atmos music on it is amazing. It's every bit as revolutionary as claimed.

  However, I like to own music and that is simply impossible at the moment for most Atmos recordings. I would love to build a library of such recordings, preferably in physical form, and would happily spend quite a lot of money doing so. But Apple Music is basically the only way I can listen to anything.

  I can't help but suspect this is entirely deliberate, an attempt to use this innovation to hasten the passing of the concept of owning music into the past.

  Sadly, I also worry the move to streaming means an awful lot of music is eventually going to be lost forever.

• by recursive on 2/2/24, 8:13 PM

  I'm a grumpy old man, and no one can ever make me care about any audio transport fancier than analog stereo. To my dismay, it's getting hard to find TVs that can even provide usable stereo output without some kind of extra decoder box or something. Luckily, last time I bought a TV, I was still (barely) able to find one that had a headphone jack, which I use as a stereo line out.

• by aidenn0 on 2/2/24, 7:33 PM

  I gave up on getting audio passthrough to work reliably and just send PCM over HDMI. I don't think there are downsides to this, unless my computer is somehow worse at decoding DTS than my AV receiver?

• by theandrewbailey on 2/3/24, 2:55 AM

  I'm sad that PC surround sound is (mostly) either multiple analog wires to plain old speakers, or HDMI to a receiver. HDMI mostly works, but it's not ideal, since running it through the video card and drivers introduces points of failure, and needs a monitor output to piggy back off of to work. (That's fine for a TV, but PC audio and video are separate concerns.) Why can't they use USB instead? Is the market too small? Receivers have had USB ports for years, but those are for playing MP3s off a flash drive. A PC isn't a flash drive.

• by NoPedantsThanks on 2/2/24, 8:13 PM

  All the Atmos PR and descriptions talk about "objects," but they never say how those objects' sounds are separated from the others' in the datastream. How can, for example, 56 waveforms be carried independently in one stream?

  The use of Atmos in music is just plain bad. How many pop recordings are actually mixed for Atmos? I can't imagine that it's as many as Apple is presenting "in Atmos" on Apple Music. So is there some post-processing BS going on, a la "Q-Sound" and other fake surround over the past few decades?

  Here's an example of Atmos messing up music. It's too bad it happens, too, because the Atmos versions of songs seem to be less dynamically compressed: https://www.youtube.com/watch?v=xUgfp6mFG2E

• by atoav on 2/3/24, 9:52 AM

  Ad the part about cables:

  If you have long cable runs I'd use an optical signal or a balanced line signal (this is why professional audio gear has balanced outputs and inputs with TRS 6.3mm or XLR-3 connectors).

  There are simple adapters that allow you to send 4 balanced audio signals over existing ethernet connections. With CAT6 you can easily push balanced signals over a kilometer (long beyond the 100m treshold of actual CAT6 ethernet) without any noticable degradation.

  If you have unbalanced signals from weak sources (vinyl needle?) you should keep the cable runs short, but even if the driver is good it can help to add a balun (passive or active) to run the thing balanced when the cable run is longer than 10 meters or is in a harsh environment (e.g. power chords with bursty loads emitting EMF).

• by qozoq on 2/2/24, 8:17 PM

  VLC and other PC based software has always left me with just as many problems - if not more - regarding picture quality, as well as audio. The gold standard for me - this goes for three TVs going back 12 years - has always turned out to be to use the TV's own media player app, in conjunction with a solid DNLA server.

  Otherwise it's gripes over finding the ideal combination of TV picture settings AND OS display settings. The TV is an OS of it's own, of course. How does one go about tweaking two sets of settings that overlap?

• by duped on 2/2/24, 7:42 PM

  > But what about object-based surround sound? I'm using that somewhat lengthy term to try to avoid singling out one commercial product, but, well, there's basically one commercial product: Dolby Atmos.

  In theory, the recent(ish)ly standardized SMPTE 2098-2 bitstream protocol will allow for 3rd party encoders/decoders of object-based "immersive audio." In practice, 2098-2 is the bastard child of Atmos and DTS:X and I kind of doubt we'll ever see a FOSS decoder.

  But anything's possible.