Audio - Qualcomm Dragonwing Documentation

The IQ-9075 audio subsystem is powered by Low Power AI (LPAI) and delivers advanced voice UI and audio experiences via PipeWire.

Key Features

Low Power AI (LPAI) subsystem for efficient audio processing
PipeWire multimedia server for low-latency audio routing
Hardware-accelerated encoding/decoding
Fluence ECNS — advanced echo cancellation and noise suppression
Multiple audio interfaces — I2S, TDM, SoundWire

Hardware Configuration

Speakers: Onboard MAX98357 I2S amplifiers; connect the two supplied mini speakers to hear output. HS0_MI2S is shared between left and right for stereo.
Microphone: Single onboard microphone (MMICT5848) on HS2_MI2S, configured to left channel by default

Speaker connection:

Microphone location:

Architecture

Component	Description
PipeWire	Multimedia server; replaces PulseAudio; low-latency, flexible media handling
WirePlumber	Session/policy manager; handles default sink/source, auto-connect rules
PAL	Platform Abstraction Layer; provides audio-specific APIs and DSP graph operations
AGM	Audio Graph Manager; ALSA-based mixer controls and PCM/compressed plug-ins
ARGS/GSL	AudioReach Graph Service; handles initialization and creation of audio graphs
SPF	Signal Processing Framework; modular framework on LPAI DSP

Configuration Files

Component	Location
ALSA card registration	`/proc/asound/cards`
UCM2 profiles	`/usr/share/alsa/ucm2/<card-name>/`
PipeWire config	`/etc/pipewire/`
WirePlumber rules	`/usr/share/wireplumber/`

Verify Audio Stack

cat /proc/asound/cards                                   # List registered ALSA sound cards
aplay -l                                                 # List playback (output) devices
arecord -l                                               # List capture (input) devices
systemctl --user status pipewire wireplumber --no-pager  # Confirm the audio services are active
wpctl status                                             # Show the default sink/source and routing
pw-top                                                   # Live view of the audio graph (Ctrl+C to exit)
pw-cli ls Node                                           # List PipeWire nodes

Expected: /proc/asound/cards lists at least one card, and aplay -l and arecord -l each show a device. For example:

 0 [<card-name>     ]: <driver> - <card description>
                       <card long name>

**** List of PLAYBACK Hardware Devices ****
card 0: <card-name> [<card description>], device 0: <pcm-name> []
  Subdevices: 1/1

wpctl status should list a default Sink and Source (each marked with *). If /proc/asound/cards is empty or wpctl status shows no default sink or source, the audio stack did not come up: see the Troubleshooting section below.

Audio Playback and Capture

PipeWire Playback

Push audio file to device

Copy a short test clip to the device so you have something to play. test.wav is any small PCM WAV file (48 kHz, 16-bit stereo works well): use one from the host, or create one with ffmpeg -f lavfi -i "sine=frequency=440:duration=5" -ar 48000 -ac 2 test.wav.

scp test.wav ubuntu@<ip-addr>:/home/ubuntu/

Set default sink and volume

wpctl status   # Find sink node marked with *
wpctl set-default <sink-node>   # If not already set
wpctl set-volume @DEFAULT_AUDIO_SINK@ 1.0

Play audio

pw-play /home/ubuntu/test.wav -v

You should hear the clip play through the connected speakers, and pw-play prints a progress and peak-level readout while it runs:

Press Ctrl+C to stop.

PipeWire Record

Set default source and volume

wpctl status   # Find mic node marked with *
wpctl set-default <mic-node>   # If not already set
wpctl set-volume @DEFAULT_AUDIO_SOURCE@ 1.0

Start recording

pw-record /home/ubuntu/record.wav -v

Press Ctrl+C to stop.

A value of 1.0 represents 100% volume.

GStreamer Audio

Capture
Playback

# PCM capture
gst-launch-1.0 -v pulsesrc volume=10 ! audioconvert ! wavenc ! \
  filesink location=/home/ubuntu/audio.wav

# FLAC capture
gst-launch-1.0 -v pulsesrc volume=10 ! audioconvert ! flacenc ! \
  filesink location=/home/ubuntu/audio.flac

# WAV playback
gst-launch-1.0 -e filesrc location=/home/ubuntu/audio.wav ! \
  wavparse ! audioconvert ! pulsesink volume=10

# MP3 playback
gst-launch-1.0 -e filesrc location=/home/ubuntu/audio.mp3 ! \
  mpegaudioparse ! mpg123audiodec ! pulsesink volume=10

# FLAC playback
gst-launch-1.0 -e filesrc location=/home/ubuntu/audio.flac ! \
  flacparse ! flacdec ! pulsesink volume=10

Log Capture

# PipeWire logs
journalctl --user -u pipewire
journalctl --user -u wireplumber

# Live debugging
journalctl --user -u pipewire -f

# Kernel audio driver logs
sudo dmesg

Troubleshooting

No Audio Output During Playback

wpctl status
wpctl set-volume @DEFAULT_AUDIO_SINK@ 1.0
systemctl --user restart wireplumber
aplay -l

Verify speakers are connected properly
Increase volume if at 0%
Restart WirePlumber if PipeWire is not routing correctly

No Audio Capture from Microphone

# Check ALSA capture devices
arecord -l
dmesg | grep -i "snd\|audio\|asoc"

# Test raw ALSA recording (bypass PipeWire)
arecord -D hw:0,0 -f S16_LE -r 48000 test.wav
aplay test.wav

# Check PipeWire capture nodes
pw-cli ls Node | grep -i source

# Check services
systemctl --user status pipewire pipewire-pulse wireplumber

If ALSA capture fails → kernel/DT is the first place to check.

Audio Playback Stuttering or Crackling

# Check CPU load
top

# Check PAL media config (expect rate=48000, ch=2, fmt=2)
grep "setDeviceMediaConfig" /var/log/syslog

# Check for underruns
dmesg | grep -i -e underrun -e xrun -e lpass -e audio

# Check PipeWire quantum
pw-metadata -n settings

# Monitor real-time
pw-top

Fix — increase PipeWire buffer:

mkdir -p ~/.config/pipewire/pipewire.conf.d
cat > ~/.config/pipewire/pipewire.conf.d/99-custom-buffer.conf << 'EOF'
context.properties = {
    default.clock.quantum = 1024
    default.clock.min-quantum = 1024
}
EOF
systemctl --user restart pipewire wireplumber

Fix — convert audio to 48 kHz 16-bit stereo:

ffmpeg -i input.wav -ar 48000 -ac 2 -sample_fmt s16 output.wav

PipeWire Service Not Starting

systemctl --user status pipewire pipewire-pulse wireplumber
journalctl --user -u pipewire -u wireplumber -b

# Reset configuration
rm -rf ~/.config/pipewire ~/.config/wireplumber
systemctl --user daemon-reload
systemctl --user restart pipewire pipewire-pulse wireplumber

# Reinstall if needed
sudo apt install --reinstall pipewire wireplumber pipewire-pulse

Advanced Features

Echo Cancellation (ECNS) for VoIP

# VoIP record
pw-record /home/ubuntu/record_voip.wav -v --target=voip-tx0

# VoIP playback
pw-play /home/ubuntu/record_voip.wav -v --target=voip-rx0

Features: adaptive echo cancellation, stationary and non-stationary noise suppression, acoustic echo path cancellation.

​Key Features

​Hardware Configuration

​Architecture

​Configuration Files

​Verify Audio Stack

​Audio Playback and Capture

​PipeWire Playback

​PipeWire Record

​GStreamer Audio

​Log Capture

​Troubleshooting

​Advanced Features

​Echo Cancellation (ECNS) for VoIP

​Resources

Key Features

Hardware Configuration

Architecture

Configuration Files

Verify Audio Stack

Audio Playback and Capture

PipeWire Playback

PipeWire Record

GStreamer Audio

Log Capture

Troubleshooting

Advanced Features

Echo Cancellation (ECNS) for VoIP

Resources