I understood that Elk Audio OS on RPi supports specific AD/DAC from HiFiBerry.
But are USB AD/DAC (like e.g. Behringer UCA222) also supported?
Are there any pro’s/con’s to be aware of?
Hi @ro5,
unfortunately no USB audio support.
Elk Pi images use RASPA / Xenomai for their driver architecture, and writing a USB driver is much more complicated than a I2S / TDM one (or SPI as we use in other configurations).
If you’re interested in getting some features of Elk without the ultra-low latency Xenomai setup, you can get e.g. a Raspbian image with the JACK audio server (and better if tuned with PREEMPT_RT etc.) and build SUSHI for it. In that case, you’ll be able to support any USB soundcard that work on standard Linux.
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Hi. Just like to know if the above technique would work with non-hifiberry I2S soundcards (in my case Fe-Pi V1)?
HI @SyntheticMete,
you need to have a I2S soundcard with the same converter ICs that are there on the HiFiberry.
I’ve just looked briefly at the Fe-Pi that you mentioned and unfortunately, that won’t work since it uses a different WM codec. It is possible to adapt the driver for that codec but it’s a job that requires some familiarity with Linux driver development.
Thanks for the response. I do have some other I2S cards (D/A only so no inputs), will check them.
I was actually looking into this, but felt deterred when I read this CMake option description:
| SUSHI_WITH_JACK | on / off | Build Sushi with Jack Audio support, only for standard Linux distributions and macOS. |
Is it possible to build with Jack support with Raspberry Pi 4 as the target platform?
Another question is whether such a setup could perhaps gain anything from your real-time kernel patch above PREEMPT_RT, or if it’s only beneficial in conjunction with Xenomai? Going by the visualization showing the differences between non-rt, PREEMPT_RT and Elk OS operation, Elk is a pretty tempting choice to just slap on an SD card anyway.
Hi Nnarol and welcome to the forums. You can certainly build sushi with jack on a Raspberry Pi 4, though with Raspbian or any other distro with jack included, not with Elk Audio OS.
You could also run sushi with Jack with a PREEMPT_RT patched kernel, though in that case sushi will not gain any lower latency than any other daw. In order to get the really low latency of Elk Audio OS, you need to use Xenomai/EVL for audio processing and that is only accessed via the Raspa api instead of Jack or Alsa.
Hi, I am using RPi with USB audio devices, meaning I cannot use the “superlow” latency of ELK OS/RASPA. Are there any benchmarks that shows the latency difference between current ELK OS and a standard raspberry pi os with jack and rt-patched kernel?
Hi @helander, there is this AES article with benchmarks doing this comparison:
Any chance you could reveal any details without me having to purchase the paper?
The tl;dr is that with Elk/Xenomai we were able to achieve stable latencly down to 16 samples @48kHz compared to 32 with PREEMPT_RT/Jack, and more importantly there was more headroom available for DSP processing (+50% computational power at the same latency).
The tests were done on RPi4 + HifiBerry, and we tried to make them as “fair” as possible by optimizing the PREEMPT_RT solution as best as we could.