birdnet-esp32-rtsp-mic

Seeed XIAO ESP32 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: v1.21 (2026-07-22)
• 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-<board>.bin (firmware-app.bin remains the C6 alias)
• 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.

Supported XIAO boards:

• Seeed Studio XIAO ESP32-C3
• Seeed Studio XIAO ESP32-S3
• Seeed Studio XIAO ESP32-C5
• Seeed Studio XIAO ESP32-C6

Default build notes:

• The web flasher detects the connected ESP chip family and selects the matching firmware.
• XIAO ESP32-C6 external antenna RF switch is enabled by default.
• XIAO ESP32-C3, XIAO ESP32-S3, and XIAO ESP32-C5 use their U.FL antenna path without firmware GPIO switching.
• 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.
• Automatic OTA uses a board-specific stable URL, so installed firmware always downloads the latest published C3/S3/C5/C6 app image instead of rebuilding its own current-version URL.
• For manual OTA upload, use the matching app-only file from manual-ota-firmware/.

Wiring

Tested build targets: Seeed Studio XIAO ESP32-C3/S3/C5/C6. Runtime hardware validation is still primarily on XIAO ESP32-C6 + ICS-43434 I2S microphone.

Use the same physical XIAO pin labels on every supported board. The underlying GPIO numbers differ by chip.

Firmware v1.11 or newer is required for the C3/S3/C5 GPIO mappings below. Versions 1.10.0 and 1.10.1 incorrectly used the C6 GPIO mapping (21/1/2) in every board build. C6 was not affected.

Mic signal	XIAO pin label	C3 GPIO	S3 GPIO	C5 GPIO	C6 GPIO	Notes
BCLK / SCK	D3	5	4	7	21	I2S bit clock
LRCLK / WS	D1	3	2	0	1	I2S word select
SD / DOUT	D2	4	3	25	2	I2S data from microphone
MCLK / SCKI	D7	20	44	12	17	Optional clock for PCM1808 ADC
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

Firmware v1.21 also outputs a 256-fs MCLK on D7 for experimental PCM1808 ADC setups. Configure the PCM1808 for slave I2S mode and connect the microphone path to its left input; RTSP output remains mono. This path is ready for hardware testing but is not yet a tested reference setup. Existing ICS-43434 and INMP441 installations leave D7 unconnected and require no wiring change.

XIAO Antennas

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.
• XIAO ESP32-C3 and XIAO ESP32-S3 expose a U.FL antenna connector without a documented firmware GPIO switch.
• XIAO ESP32-C5 has a dedicated Wi-Fi/BT antenna connector; attach the included antenna before use.
• 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() for the C6 build.

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.

Default audio settings are 48 kHz, mono 16-bit PCM/L16, gain 1.5, and a 512-sample packet buffer. The 512-sample default is the balanced profile and avoids the BirdNET-Pi UDP stutter observed with 1024-sample packets, while still working well for BirdNET-Go TCP. Firmware v1.9.3 and later improves BirdNET-Pi UDP compatibility by handling RTCP and RTP metadata expected by ffmpeg-based clients.

Recommended Hardware

Part	Qty	Notes	Link
Seeed Studio XIAO ESP32-C3	1	Supported XIAO target board	Seeed Studio
Seeed Studio XIAO ESP32-S3	1	Supported XIAO target board	Seeed Studio
Seeed Studio XIAO ESP32-C5	1	Supported XIAO target board	Seeed Studio
Seeed Studio XIAO ESP32-C6	1	Supported XIAO target board	Seeed Studio
MEMS I2S microphone ICS-43434	1	Tested reference microphone	AliExpress
MEMS I2S microphone INMP441	1	Reported compatible with same wiring	-
Shielded cable, 5+ core	Optional	I2S mic needs 5 conductors: 3V3, GND, BCLK, LRCLK/WS, and SD/DOUT. A 6-core cable is a good practical choice for spare/shield handling.	AliExpress
5 V power supply	1	At least 1 A recommended	AliExpress
2.4 GHz antenna, IPEX/U.FL	Recommended	Important for stable XIAO Wi-Fi streaming	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 boards: Seeed Studio XIAO ESP32-C3, XIAO ESP32-S3, XIAO ESP32-C5, and XIAO ESP32-C6.
• Web flasher auto-selects firmware by ESP chip family. It cannot distinguish board variants that share the same chip family.
• 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 and later 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 tight XIAO ESP32-C3/C6 default 1.2 MB app partitions below the limit 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.