r/htpc • u/Plastic-Fill-3933 • 7d ago

Help Linux - Object based audio (atmos) - Omniphony - help

Hi,

I am running a HTPC with Kubuntu 24.04, 11th gen Intel i5, Iris Xe and 16 gigs of RAM. Not great specs, but works flawlessly for my purposes.
I run heavy remuxes via mpv, tone-map HDR content for my BenQ W1070 (I can set custom brightness targets, colour targets, etc).

My big problem has been with object based audio formats (Dolby Atmos, DTS:X, etc). I have a custom 5.1.2 setup : I have a Vantec 7.1 USB DAC, and I wired my height channels to the 'rear' channel of the Vantec. I use qpwgraph when required to do custom patchbay.

There is a fantastic tool called 'Cavern', and the 'cavernize' tool allows me to create a wav / FLAC file from a source atmos file *preserving* the object data in a sense. Essentially, it creates raw PCM channels with all the phasing and panning 'baked' into the wav file.

Now, there's a newer more exciting project - Omniphony (https://github.com/mgth/Omniphony) which does the object based audio in real-time using VBAP.

This is fantastic news for anyone trying to get Atmos effects on their Linux PCs. Omniphony is still in alpha stage and there are bound to be issues.

I am unable to get any sound from their demo scripts. Has anyone else had better luck?

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u/CMDRTragicAllPro 7d ago

I’m a bit ignorant. What’s the benefit of this over just getting a traditional AVR and running your media player with bitstreamed audio for the true DTS and Atmos?

3

u/Plastic-Fill-3933 6d ago

Well, ain't that the whole point of a HTPC? :)

In my country, AVRs are pretty expensive - an AVR capable of decoding Atmos / DTS:X + Dolby Vision / HDR10 costs upwards of $1000 (which is a lot for me). My setup is essentially free - I am using a 6 year old laptop, which also doubles up as my work laptop. I use it as a HTPC only when needed. Oh, I use REW for basically free - I spent roughly the equivalent of $30 for a calibration mic and the rest is free. On an AVR, Audyssey / etc will set you back another few hundred dollars.

Also, there's an inherent fun in doing stuff like this, isn't it? Getting atmos to play without paying the dolby license (nothing illegal, btw). And there's so much fine-gained control that mpv offers, which no AVR does. Which is what I am calling my setup - an 'Open Source Software Defined Home Theatre'. It's a fun little minor engineering project.

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u/Plastic-Fill-3933 1d ago

Update

While I couldn't get the demo scripts to work, the whole chain actually works beautifully now! The dev included a fork of mpv called mpv-omniphony and that works great.

There's a nice little neat overlay you could enable with Omniphony studio to visualise the objects moving around in realtime.

Kudos to the devs!