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ESP32 RTSP Mic for BirdNET-Go / BirdNET-Pi

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: v1.10.0 (2026-06-11)
  • 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:

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.
  • 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.

Wiring / pinout

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

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
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 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 1.2, 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.

About

RTSP I2S microphone streamer based on ESP32 XIAO boards for BirdNET-Go / BirdNET-Pi. Dual streams (/audio1, /audio2), Web UI, JSON API, OTA updates, and built-in auto-recovery for stable 24/7 operation.

esp32mic.msmeteo.cz/

Topics

audio rtsp esp32 audio-streaming mic xiao rtsp-stream birdnet esp32s3 esp32c3 birdnet-pi esp32c6 birdnet-go birdnetgo bird-net ics43434 streammic xiaoc6 birdnetpi esp35c5

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