birdnet-esp32-rtsp-mic

ESP32-C6 network microphone for BirdNET-Go and BirdNET-Pi. It reads an I2S MEMS microphone and serves mono 16-bit PCM/L16 audio over RTSP.

• Latest firmware: v1.9.2 (2026-05-16)
• Target sketch: esp32-birdnet-mic
• Web flasher: https://esp32mic.msmeteo.cz (Chrome/Edge desktop, USB-C data cable)
• Manual OTA firmware: manual-ota-firmware/firmware-app.bin
• Detailed firmware docs: esp32-birdnet-mic/README.md
• Changelog: esp32-birdnet-mic/CHANGELOG.md
• License: MIT (LICENSE)

Quick Start

1. Open https://esp32mic.msmeteo.cz.
2. Click Flash, select the USB JTAG/serial device, and wait for reboot.
3. On first boot, connect to Wi-Fi AP ESP32-RTSP-Mic-AP.
4. Open http://192.168.4.1 if the captive portal does not appear, then enter your Wi-Fi details.
5. After reboot, open the device Web UI at http://<device-ip>/.
6. Use these RTSP URLs in BirdNET-Go, BirdNET-Pi, VLC, or ffplay:

rtsp://<device-ip>:8554/audio1    Stream 1
rtsp://<device-ip>:8554/audio2    Stream 2

If mDNS is enabled and works on your LAN, the same streams are available through the device hostname:

rtsp://<device-hostname>.local:8554/audio1
rtsp://<device-hostname>.local:8554/audio2

The default hostname is unique per device, for example esp32mic-a1b2c3.

Default build notes:

• XIAO ESP32-C6 external antenna path is enabled by default.
• OTA has no password in the default public build. Keep the device on your trusted LAN.
• For OTA without USB, open https://esp32mic.msmeteo.cz, enter the device IP in the OTA section, and open the device update page.
• For manual OTA upload, use manual-ota-firmware/firmware-app.bin on the device update page.

Wiring

Tested hardware: Seeed Studio XIAO ESP32-C6 + ICS-43434 I2S microphone.

Mic signal	XIAO ESP32-C6 GPIO	Notes
BCLK / SCK	21	I2S bit clock
LRCLK / WS	1	I2S word select
SD / DOUT	2	I2S data from microphone
VDD	3V3	Power
GND	GND	Ground

INMP441 has also been reported to work with the same I2S pins. If your board exposes L/R or SEL, set it to the left channel, usually GND, because the firmware reads the left I2S channel. See discussion #25: #25

XIAO ESP32-C6 Antenna

XIAO ESP32-C6 uses an RF switch path controlled by GPIO3/GPIO14. The firmware selects the external antenna path by default.

• Use a 2.4 GHz external antenna for stable RTSP streaming.
• Weak Wi-Fi can cause packet loss, retries, and extra heat.
• If your hardware intentionally uses the internal antenna path, adjust or remove the GPIO3/GPIO14 antenna-control block in setup().

Test The Stream

Use /audio1 for stream 1 unless you specifically need the old /audio URL.

ffplay -rtsp_transport tcp rtsp://<device-ip>:8554/audio1
ffprobe -rtsp_transport tcp rtsp://<device-ip>:8554/audio1

For VLC: Media -> Open Network Stream -> paste rtsp://<device-ip>:8554/audio1 or rtsp://<device-ip>:8554/audio2.

If VLC/ffplay works, use the same RTSP URL in BirdNET-Go or BirdNET-Pi.

What The Firmware Provides

• English Web UI on port 80 with live status, settings, logs, and actions.
• JSON API for automation and monitoring.
• Two RTSP streams: /audio1 and /audio2; /audio is an alias for /audio1.
• Configurable 1-3 concurrent RTSP sessions; default is 2.
• Per-stream enable/disable and BirdNET-Go / BirdNET-Pi target selection.
• Transport selection based on target: TCP for BirdNET-Go, UDP for BirdNET-Pi.
• Dedicated audio producer task with ring buffer between I2S capture and RTSP packet output.
• Audio/API diagnostics for I2S errors, ring-buffer drops, and RTSP write stalls/timeouts.
• MQTT telemetry and Home Assistant MQTT Discovery.
• Stream schedule by local time, including overnight windows.
• Optional deep sleep outside the stream schedule window.
• Auto-recovery, scheduled reset, CPU frequency control.
• Thermal protection with persistent latch and manual acknowledgement.
• Configurable high-pass filter for low-frequency rumble.
• mDNS hostname support and OTA support.

Recommended Hardware

Part	Qty	Notes	Link
Seeed Studio XIAO ESP32-C6	1	Tested target board	AliExpress
MEMS I2S microphone ICS-43434	1	Tested reference microphone	AliExpress
MEMS I2S microphone INMP441	1	Reported compatible with same wiring	-
Shielded cable, 6 core	Optional	Helps on longer microphone runs	AliExpress
5 V power supply	1	At least 1 A recommended	AliExpress
2.4 GHz antenna, IPEX/U.FL	Recommended	Important for XIAO ESP32-C6 stability	AliExpress

Links are examples only. Verify the exact part number before buying.

Practical Tips

• Keep I2S wires short; use shielded cable for longer runs.
• Keep the microphone and I2S wires away from the ESP32 antenna/RF area.
• Aim for Wi-Fi RSSI better than about -75 dBm.
• Use DHCP reservation or fixed IP if BirdNET cannot resolve mDNS reliably.
• Keep the device on a trusted LAN; do not expose HTTP/RTSP to the public internet.

RF Noise / Wi-Fi TX Power

If the stream is stable but the audio is noisy or distorted, try lowering Wi-Fi TX Power in the Web UI. When the access point is nearby, lower TX power can reduce RF coupling into the microphone, wiring, or power rails.

Suggested test:

1. Set Wi-Fi TX Power to about 11 dBm.
2. Watch RSSI, packet rate, reconnects, and audio quality for a few minutes.
3. If Wi-Fi becomes unstable, raise TX power step by step.

A grounded metal enclosure can help shield microphone wiring, but keep the Wi-Fi antenna outside the metal enclosure.

High-Pass Filter

The firmware includes a configurable high-pass filter to reduce low-frequency rumble.

• Default: ON at 500 Hz.
• Typical range: 300-800 Hz.
• Web UI: Audio -> High-pass and HPF Cutoff.
• API: POST /api/set with key=hp_enable&value=on|off or key=hp_cutoff&value=600.
• Mutating API calls require header X-ESP32MIC-CSRF: 1.

Compatibility

• Target board: ESP32-C6, tested with Seeed Studio XIAO ESP32-C6.
• Reference microphone: ICS-43434.
• Reported compatible microphone: INMP441 with the same I2S wiring.
• Other ESP32 boards or I2S microphones may work, but may need pin or I2S format changes.

Arduino IDE Build Size

Firmware v1.9.2 includes esp32-birdnet-mic/build_opt.h, which the ESP32 Arduino core loads automatically in Arduino IDE and arduino-cli. It disables unused C++ exception/unwind metadata and keeps the default XIAO ESP32-C6 partition scheme below the 1.2 MB app limit with about 60 KB reserve, without removing firmware features.

More Documentation

• Firmware details, build instructions, API notes: esp32-birdnet-mic/README.md
• Manual OTA firmware: manual-ota-firmware/README.md
• Web flasher notes: web-flasher/README.md
• Firmware changes: esp32-birdnet-mic/CHANGELOG.md

License

This project is released under the MIT License. See LICENSE.