AudioMixer bad on Pygamer / SAMD51 on CirPy 10.x #10867
Description
CircuitPython version and board name
Adafruit CircuitPython 10.1.2-14-gf75864d25f on 2026-03-03; Adafruit PyGamer with samd51j19
Adafruit CircuitPython 10.1.3 on 2026-02-20; Adafruit PyGamer with samd51j19
Adafruit CircuitPython 10.0.1 on 2025-10-09; Adafruit PyGamer with samd51j19Code/REPL
import time
import board, digitalio
import displayio
import audiocore, audiomixer, audioio
displayio.release_displays() # just in case
SAMPLE_RATE = 22050
CHANNEL_COUNT = 1
BUFFER_SIZE = 4096
spkr_enable = digitalio.DigitalInOut(board.SPEAKER_ENABLE)
spkr_enable.switch_to_output(value=True)
audio = audioio.AudioOut(left_channel=board.A0)
mixer = audiomixer.Mixer(sample_rate=SAMPLE_RATE, buffer_size=BUFFER_SIZE,
channel_count=CHANNEL_COUNT, voice_count=1)
audio.play(mixer)
mixer.voice[0].level = 0.25
wav1 = audiocore.WaveFile("amen1_22k_s16.wav")
mixer.voice[0].play(wav1, loop=True) # does not work on PyGamer / SAMD51, bare whisper of distorted audio
# audio.play(wav1, loop=True) # this works
while True:
print("hi", time.monotonic())
time.sleep(0.3)Behavior
On CircuitPython 9.2.9 and before, using AudioMixer works as expected.
As of 10.0.1, it outputs a barely-audible distorted version of the audio.
Bypassing AudioMixer with audio.play(wav) works as expected on all versions of CirPy.
Description
I'm currently thinking it's related to this commit fd2627c that added the very nice mono-to-stereo conversion.
I don't see any changes to "atmel-samd/common-hal/audioio" in the last two years, so I don't think it's port-specific, but rather < 16-bit audio destinations are giving AudioMixer issues?
Additional information
Works on Adafruit CircuitPython 9.2.9 on 2025-09-07; Adafruit PyGamer with samd51j19