Overview
The audio node provides audio recording and playback capabilities
through ALSA (Advanced Linux Sound Architecture). Use it to record voice memos, play alert sounds,
detect available audio devices, and control system volume on your Raspberry Pi or Linux device.
Properties
| Property | Type | Default | Description |
|---|---|---|---|
| operation | select | "detect" | Operation: "record", "play", "detect", or "volume" |
| device | string | "default" | ALSA device name (e.g., "hw:0,0", "plughw:1,0") |
| format | select | "wav" | Audio format: "wav" or "raw" |
| sampleRate | select | "44100" | Sample rate: "8000", "16000", "22050", "44100", or "48000" |
| channels | select | "1" | Audio channels: "1" (mono) or "2" (stereo) |
| bitDepth | select | "16" | Bit depth: "8", "16", "24", or "32" |
| duration | number | 5 | Recording duration in seconds |
| volume | number | 75 | Playback volume percentage (0-100) |
| outputDir | string | "/tmp/edgeflow-audio" | Directory to save recorded audio files |
Inputs
Any incoming message triggers the configured operation. Override settings via payload properties.
{
"payload": {
"operation": "record",
"duration": 10,
"sampleRate": "16000"
}
}Outputs
{
"payload": {
"filepath": "/tmp/edgeflow-audio/rec_001.wav",
"duration": 5,
"format": "wav",
"sampleRate": 44100,
"channels": 1
}
}{
"payload": {
"status": "complete",
"filepath": "/home/pi/alerts/alarm.wav",
"volume": 75
}
}{
"payload": {
"devices": [
{ "id": "hw:0,0", "name": "bcm2835 Headphones" },
{ "id": "hw:1,0", "name": "USB Audio Device" }
]
}
}{
"payload": {
"volume": 80,
"device": "default"
}
}Example Flows
Temperature Alert with Audio Warning
Play an alarm sound when temperature exceeds threshold.
[
{
"id": "temp-sensor",
"type": "dht22",
"pin": 4,
"interval": 5
},
{
"id": "check-temp",
"type": "switch",
"property": "payload.temperature",
"rules": [
{ "t": "gt", "v": "35" }
]
},
{
"id": "set-alarm",
"type": "change",
"rules": [
{ "t": "set", "p": "payload.filepath", "to": "/home/pi/sounds/alarm.wav" }
]
},
{
"id": "play-alarm",
"type": "audio",
"operation": "play",
"volume": 90
}
]Scheduled Audio Monitoring
Record 30-second audio clips every 10 minutes for environmental monitoring.
[
{
"id": "schedule",
"type": "inject",
"repeat": "600",
"payload": ""
},
{
"id": "record-audio",
"type": "audio",
"operation": "record",
"duration": 30,
"sampleRate": "16000",
"channels": "1",
"format": "wav",
"outputDir": "/home/pi/audio-logs"
},
{
"id": "log-result",
"type": "debug",
"name": "Audio Recorded"
}
]List Available Audio Devices
Scan and display all ALSA-compatible audio devices on the system.
[
{
"id": "scan-trigger",
"type": "inject",
"payload": "",
"once": true
},
{
"id": "detect-devices",
"type": "audio",
"operation": "detect"
},
{
"id": "show-devices",
"type": "ui-table",
"name": "Audio Devices"
}
]Common Use Cases
Voice Alerts
Play pre-recorded warnings when sensors detect anomalies or thresholds are exceeded.
Environmental Monitoring
Record ambient sound for wildlife tracking, noise level analysis, or acoustic sensing.
Intercom System
Build a two-way intercom by combining record and play operations across devices.
Doorbell & Notifications
Trigger audio chimes from button presses, MQTT messages, or webhook events.