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HiFiBerry for Real-Time Audio Sharing (e.g. Jamulus, SonoBus)?

Matthew

November 11, 2024 15:47

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I am looking to be able to provide an easy-to-use, ultra-low-latency, real-time audio device to fellow musicians to facilitate remote/virtual rehearsals using software such as Jamulus or SonoBus.  Essential to this capability is keeping latency as low as absolutely possible (if total end-to-end latency exceeds 25 - 40 milliseconds [including network delays between physical locations], then remote rehearsal just isn't workable).

 

To that end, I have seen HiFiBerry products recommended as having low latency.  As such, I would like to inquire more specifically as to the potential suitability of HiFiBerry products for this.

 

Must haves:

•  Microphone input (dynamic mics are fine)
•  Audio output for headphones
•  Case designed for use with the Raspberry Pi hat
•  Real-time or low-latency OS
•  Run Jamulus or SonoBus
•  Easy for non-technical users

 

Nearly must haves:

• Integrated mount on case for official Raspberry Pi touchscreen display; usable with the official Raspberry Pi Touch Display or Touch Display 2 with optional extra-length cable.

 

Nice to haves:

• Balanced XLR audio inputs
• Stereo audio output for headphones
• Stereo audio input
• Run Audacity

 

 

Would a HiFiBerry-based setup such as the following be suitable, or is there a different configuration that might be recommended instead?

 • Raspberry Pi 5

 • HiFiBerry DAC2 ADC Pro

   - Is it possible to reconfigure (e.g. via jumper) the 1/8” input jack as a balanced mono input (instead of as an unbalanced stereo input)?

 • HiFiBerry Steel Case Pi5

 • HiFiBerryOS64

   - While neither Jamulus or SonoBus are currently listed as supported, how feasible might it be for support to be added?

 

 

Thank you!

 

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4 comments

• 0
  
  HiFiBerry team November 11, 2024 17:51

  A few comments here:
  
  > Real-time or low-latency OS
  Many users think that a realtime kernel is a good thing for audio. It can be, if you know exactly what to do. Just installing a real-time kernel often makes things worse if you're not familiar with every detail of the application as you have to configure it correctly. 
  Therefore, we do NOT recommend this for "normal" users. 
  
  > Easy for non-technical users
  If you want something, that you can "just use", have a look at commercial offerings like JackTrip. They spend a lot" of time making sure it works for "normal" people. Jacktrip can run on the Raspberry Pi (you don't even need a Pi5)
  
  > HiFiBerryOS64
  That's definitely not the right system for this application. HiFiBerryOS is a music player distribution. It's not designed for this type of use case. If you want to install 3rd party software, just use a general purpose OS, ideally Raspberry Pi OS.
  
  > HiFiBerry DAC2 ADC Pro

     - Is it possible to reconfigure (e.g. via jumper) the 1/8” input jack as a balanced mono input (instead of as an unbalanced stereo input)?
  No, but you can easily do this in software, if you can configure it. It's simply: channel L-channel R
• 0
  
  Matthew November 11, 2024 18:26

  I appreciate the follow up.

  As a bit of background, Jambox was a low-latency Raspberry Pi OS build for the Jamulus/SonoBus-like applications for the Raspberry Pi 4, so looking for something similar for the Raspberry Pi 5.  Where every millisecond of latency counts, a stock, general-purpose OS like Raspberry Pi OS is not ideal.

   

  This would be a dedicated setup (i.e. the Raspberry Pi would not be used for anything else), so it doesn't have to be used for other things.  Regarding ease of use, I'm fine with handling the initial setup for the group so long as the ongoing usage is straightforward (e.g. do this to join a session).

   

  Have seen JackTrip before, but it is completely unsuitable as a commercial option.  Even if following their Open Source guide for the Raspberry Pi 4, it still just installs on the stock OS.

   

  > you can easily do this in software, if you can configure it. It's simply: channel L-channel R

  I'm not sure I'm following how "channel L-channel R" will configure the input jack as balanced mono input?

   

  Thank you!

• 0
  
  HiFiBerry team November 11, 2024 19:58

  > Where every millisecond of latency counts, a stock, general-purpose OS like Raspberry Pi OS is not ideal.
  
  You can do <2ms latency with Raspberry Pi OS with 64 samples buffer sizes at 192kHz. That's doable and a "stock OS" is just fine for this. I'm not sure if anybody got a working setup with 32 samples buffer sizes - I don't know anybody. We have been working with a handful of different companies in this area in the past. Latency is caused by all kinds of stuff, the OS and the ALSA stack usually wasn't one the main issues.
  Feel free to configure an RT-kernel and try to get stable 32 samples buffer size working - it would probably be interesting for some people.  

  > I'm not sure I'm following how "channel L-channel R" will configure the input jack as balanced mono input
  
  The signal on a differential input is just a substraction of the positive and the negative signal. You can just do this in software by substracting left and right channel if you want a balanced input instead of two unbalanced.
  
  

• 0
  
  Matthew November 12, 2024 14:21

  Thank you, I'll check that out.