Distortion using ALSA inputs

[aking7]

I have a small GUI app running on a Raspberry Pi 3b+ with Rasbian Buster. The app inputs audio from an ALSA input PCM, does some processing, and plays the audio out of another ALSA PCM, a HifiBerry Amp2. After a short time the audio begins to distort, sounding like some samples are being skipped. There is no distortion unless the inputs are being used. For example, audio playback from a file sounds as expected.

I select the ALSA inputs and output using getAudioDeviceSetup() and setAudioDeviceSetup() of the AudioDeviceManager class. My processing is done inside a AudioSource::getNextAudioBlock(bufferToFill), which I set for playback using AudioSourcePlayer::setSource().

I’ve seen quite of few posts related to issues with JUCE and ALSA:

Nastiness in the ALSA wrapper

hey guys, I’m using JUCE on linux and there is a crackling/gliching problem with it. It occurs only if ins and outs are both turned on, and strangely it disappears with really low bufferrates (but not all, just certain…). Its independent from the soundcard (same glitching with two different soundcards). Jules said here the following: Blockquote Hmm, that’s interesting. Because the inputs and outputs are separate, there’s some nastiness in the ALSA wrapper to try to synchronise them, and tha…

Playback glitching with ALSA

Still no update on this? I have a very similar problem: Audio noise when input channels enabled, despite only playing a simple sine wave or something… Using PulseAudio for both input/output, Xonar D1, Ubuntu 18.04. Noise goes away if I reduce buffer size to 128 (default sample rate 44100Hz) or increase sample rate to 176400Hz (default buffer size 512) but anything in between get a pulsing buzz sound added to it

Linux/ALSA output broken

I'm using the latest JUCE and the DEMO code only, i always get crackling or distorion, i tried raising the thread priority to the max (no luck) renice (no luck) i compiled a low latency kernel (no luck). all other apps in the system work fine with ALSA, i remove pulseaudio completly from the system so there is just pure ALSA   the device is a HDA INTEL (non-usb device) [root@AMDC2543:~]# aplay -l **** List of PLAYBACK Hardware Devices **** card 0: PCH [HDA Intel PCH], device 0: ALC269VB Analo…

Has there been any progress? I saw mention of using a real-time kernel for the Raspberry Pi, but didn’t see anyone who tried. Just wanted to check before trying my hand at patching a new kernel.