Post by rogerlons on Aug 13, 2021 9:16:51 GMT -5
As I mentioned on another thread I use Volumio on my Pi... and it supports UAC2 devices a bit more universally (it seems to recognize everything I connect to it).
Volumio itself is not a Roon endpoint... but there is a Roon Bridge plugin for it (I have not tried it).
What you need to understand "up front" is that "things" like RoPiEEE and Volumio are a single monolithic combination of operating system and player program.
So, for example, when you download "Volumio", you are downloading an "all in one package" that contains both the Volumio program and a customized version of the operating system it runs on.
This makes it simple to install - just download one file, copy it onto a micro-SD card, plug it in, and turn it on.
But, if you want to get into the nuts and bolts, you can dig into the adjustments in the operating system under Volumio...
Or you could even separate the two, create your own customized version of the operating system, and run Volumio on that instead...
The same is true for RoPiEEE.
I don't use RoPiEEE but, from several posts I've read, RoPiEEE seems to need to have its support for specific DAC hardware configured individually.
In other words, it expects you to "pick your DAC off a list", or at least to be able to "look your DAC up on its list by looking it up by name", rather than offering "generic UAC2 support".
And the RoPiEEE program doesn't include much in the way of allowing you to create new items on that list or configure it manually for things that aren't on it.
But, if you're sufficiently motivated, you can still customize it, or the Linux distribution it runs on...
As I understand it, RoPiEEE is based on Arch Linux (I think), which supports UAC2...
And it includes a list of specific DACs that it "recognizes" and settings to use with them...
So, if your DAC isn't on their list of ones it's pre-configured to recognize, you would have to dig into the actual settings in Linux and manually configure it...
That sort of thing tends to be very complicated - and often not well documented (at least not at the level ordinary users can understand).
We're talking about changing settings in config files - after figuring out what they should be...
Honestly, being "limited" to 24/96k isn't really much of a hardship... 
For anyone who wants to "really get into this stuff" here's an interesting link..... (just for an idea of what would be involved)
This describes getting a different DAC to work with a different version of Linux... but the basic concepts are pretty much the same...
You would be wanting to see how Linux identifies the DAC you cannot get to work...
You would then need to either add it to RoPiEEE's list of supported devices along with the proper settings for it...
Or enter the appropriate settings directly into the Linux that RoPiEEE is running on...
(Basically, Linux should be able to "see" the DAC, since it can see UAC2 devices in general, but RoPiEEE cannot "recognize" it. That's what you need to fix.)
Things like ALSA are common to pretty much all Linux distros... but the detials may vary slightly.
Linux in general is very open so all of this stuff is almost certainly stored in a file somewhere - and you can edit it if you figure out how.
That process MIGHT require simply finding the entry for a similar DAC, making a duplicate copy of that entry, and substituting the proper DEVICE ID for the DAC you want to use.
Also - I have had zero success connecting the RPi to a USB Class 2.0 device - both the XMC-2 and my Oppo UDP-205 can work this way. In the case of the Oppo, it doesn't see it at all (no big deal because the Oppo is also a Roon endpoint)... But with the XMC-2, it means that I am limited to 96K bitrate. Assume this has to be some kind of driver issue. I have the same issue with Volumio, but at least it works over HDMI.
Anyone had success getting an RPi connected as a Class 2.0 USB device?
Thanks, Keith. I agree that (in theory) the Class 2 device should work... But in reality I think it's dependent on the specific version of Linux that the distribution is based on, and the drivers that whoever built that distro included (or not).
Also agree that 96K isn't that big of a deal, but it does mean down-sampling 192K and DSD128 (176K). And I always assume that less manipulation of a signal is better than more. And the HDMI connection seems to work fine at the higher resolutions. And I can use the HDMI connection with either the XMC or the Oppo and it seems to work just fine.
So here's a technical question that you should be able to answer. From the Emotiva side, is there any difference in the way a signal gets processed from USB vs HDMI? I have either option from the RPi4 to the XMC-2... So I am wondering if there's any difference in the way the signal is handled by the processor... I think the XMC does DSD Direct decoding over HDMI (but not USB yet). Should one be cleaner/better than the other?
