Roon downsampling to roon Bridge

Support
1

Hi all,

I am new to Roon and have playing with different configurations and I am facing an issue with my ideal one.
I am running Roon server on my Synology DS716+ NAS and everything seems responsive and working fine, but when streaming to a my endpoint (Roon Bridge on a pi3) the music are being down-sampled. I can see that Roon only identifies the endpoint as bit perfect up to 48khz and everything higher is in RED. Can also see that the problem is within Roon as it indicates that is down-sampling the music

Why is this ? What is creating this limitation ?
Pi is on WIfi and the output is the HDMI to my receiver.

Thanks,
Ricardo

2

That’s why Roon is downsampling … the limitation is the receiver is returning 48k as it’s hihest resolution.

3

Roon queries the endpoint and will only play the resolutions that the endpoint tells Roon it can handle. In your case, when Roon is testing your endpoint, it is coming back with 48 khz being the highest possible resolution and so it is down-sampling the music to match what the endpoint is telling Roon it can handle.

4

The current Pi drivers for HDMI/3,5mm audio out only support up to 48kHz. They’re also notoriously bad quality wise. Updated drivers are in development, but still in experimental stage. DietPi offers them as a choice. The so seem to improve the sound, bit bitrate is still limited to 48kHz. (More info: http://dietpi.com/phpbb/viewtopic.php?f=9&t=450#p1965).

If your receiver supports SPDIF (optical or coaxial), you may be better served by adding a Digi+ HAT by HifiBerry or IQAudio to your Pi, as it will support highres and greatly improve AQ.

5

Thanks for the replies.

After doing some digging I can see that the PI is replying back with 16bit and 48khz as the limit via HDMI.
Already updated the kernel to the latest version but no luck.

I understand this is not a Roon software issue but does anyone knows how to overcome this problem ?
It surely is not a hardware limitation which leaves a bit more annoyed!

Thanks

6

Thanks RBM.
Will order a digi+ HAT then.

Can you please clarify on the quality over usb ? (to a usb dac)
Optical or Coax will be limited to 192khz and I would like to remove the limitation if possible via HDMI or USB.

Thanks for the quick support

7

@evand: it appears the receiver is connected by HDMI, so the Pi’s HDM support is the limiting factor here.

@Ricardo_Cardoso: while USB is generally fine wth current Raspbian versions, all I/O (USB and networking) is sharing one USB 2.0 bus, limiting bandwidth. Some users have reported pops and crackles at higher resolutions (PCM and DSD).

For USB you may be better served with a different board (Cubox, Odroid, Beaglebone). I used up to DSD256 on a Cubox with no problems, while @evand appears to be having great success with his Odroids.

8

Thanks again.

Will try the HAT first and then decide what to do.
Regards,
Ricardo

9

@RBM Thanks, I had no idea the pi’s HDMI has an audio limitation.

10

I do believe that later HDMI revisions have been updated on the audio front, but for PCM, you never hear of greater than 192 kHz sample rates via HDMI, especially between a computer and an AVR.

AJ

2 Likes
11

Hi RBM,
I did tried the dietPI and the sound over hdmi using the new driver (the one with HQ in the end) is way better then the noisy one from raspian but as you mentioned the 48khz limitation is still there.
While I am waiting for the digi+ PRO to become available I am still trying to get this to work, and have realised that if you recompile the kernel with the correct settings it will work.
Do you know anything about this?
Thanks