Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

PC Based Computer music servers, crossovers, and equalization

Digital distortion using loopback module - Raspberry Pi
Digital distortion using loopback module - Raspberry Pi
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 9th April 2020, 07:42 PM   #1
DarpMalone is offline DarpMalone  Canada
diyAudio Member
DarpMalone's Avatar
Join Date: Sep 2008
Location: Toronto
Digital distortion using loopback module - Raspberry Pi
Default Digital distortion using loopback module - Raspberry Pi

Hi all,

I'm running PulseAudio Crossover Rack software on Raspian Buster & I'm experriencing horrible digital distortion when I loopback audio in PulseAudio from source back to a sink - but only when using samplerate's over 88.2k.

This happens whether I'm looping back from the input from my HiFiBerry DAC+ ADC / from a cheap USB Soundblaster input or a S/PDIF input... The strange thing is though that it plays perfectly for a few seconds, then the distortion kicks in. It's not a digital saturation type of sound but more like R2D2 "bleep-blrrrp-bdleep" almost as though something's falling out of sync after 30s of playback.

I initially thought that it was because I'm running out of CPU but this happens whether I'm using the Pi2B+, 3B or 4. Even the 2B manages loopback @ 88.2K albeit with a few minor glitches here and there.... This is not a huge problem obviously but more of a nuisance.

I'm puzzled because even the Pi3 plays 192k flawlessly with tonnes of headroom whether playing local audio/video sources, streaming DLNA sources, Network streams using PA-Prefs, Bluetooth Audio sources from my phone or laptop. It only falls apart when monitoring from a loopback source, and only when over 88.2k.

Does anyone know why this occurs?


Last edited by DarpMalone; 9th April 2020 at 07:45 PM.
  Reply With Quote
Old 10th April 2020, 07:03 PM   #2
xorcz is offline xorcz  Czech Republic
diyAudio Member
Join Date: Feb 2020
Maybe it should be in the paxor thread? I use the rack (paxor) with LR4 filters for a 3-way and on Pi3 had to go down to 48k sampling rate. Later I moved paxor to J4105 board, which can maintain 192kHz. I found out sound degradation (starts with crackling to stuttering) happens if there is >80% load on the CPU. The network (I do not use wlan) steaming is demanding. I also used pulseaudio native tunnel. But even on recent Ryzen 5 i can get crackling if there are more (even local, so no network) sources of stream (typically I play audacious and have youtube in firefox - multiple).
  Reply to this post


Digital distortion using loopback module - Raspberry PiHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Queries on Soekris DAM1021 module and Raspberry pi. daniel4381 Digital Line Level 18 23rd December 2018 07:19 AM
can anyone recommend a digital output for a raspberry pi? Miller-8 PC Based 2 2nd August 2016 03:08 PM
Digital noise on TPA3116 - I2S DAC - Raspberry Pi combo Twerp Class D 10 8th April 2016 02:53 PM
Raspberry Pi -A New DIY'ers Digital Hub? pinkmouse Digital Source 164 11th June 2013 09:21 PM

New To Site? Need Help?

All times are GMT. The time now is 09:54 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio