A versatile audio streaming solution for ESP32 that enables high-quality audio transmission over network using RTP protocol. The device can operate in four distinct modes, bridging different audio interfaces (USB/S/PDIF) with network streaming.

The ESP32 RTP Transceiver is an audio streaming device that transforms your ESP32 into a powerful audio bridge. It supports both sending and receiving audio streams over your local network using the Real-time Transport Protocol (RTP), with support for both USB Audio Class (UAC 1.0) and S/PDIF digital audio interfaces.

Screenshots:

• Four Operating Modes: Flexible configuration as sender or receiver with USB or S/PDIF interfaces
• RTP Protocol: Industry-standard real-time audio streaming
• mDNS Discovery: Automatic device discovery on local networks
• Web Configuration: User-friendly web interface with setup wizard
• OTA Updates: Over-the-air firmware updates
• NTP Synchronization: Precise time synchronization for coordinated playback
• Adaptive Buffering: Dynamic buffer management for optimal audio quality
• Power Management: Sleep modes and battery charging support (BQ25895)
• Import/Export Settings: Backup and restore device configurations

• Function: Receives RTP audio streams from the network
• Output: USB UAC 1.0 DAC
• Use Case: Stream network audio to USB speakers/DACs
• Description: Device acts as a network audio receiver, outputting audio through USB to connected DACs or speakers

• Function: Receives RTP audio streams from the network
• Output: S/PDIF digital audio
• Use Case: Stream network audio to S/PDIF equipment
• Description: Device receives network audio and outputs through S/PDIF optical/coaxial connection

• Function: Captures audio from USB host (PC/Console)
• Output: RTP network stream
• Use Case: Stream PC/console audio to network
• Description: Device appears as a USB sound card to computers/consoles and streams received audio to the network

• Function: Captures audio from S/PDIF input
• Output: RTP network stream
• Use Case: Stream S/PDIF sources to network
• Description: Device captures S/PDIF audio input and broadcasts it as RTP stream on the network

1. Lifecycle Manager (lifecycle_manager.c)

   • Central state machine controlling device operation
   • Manages mode transitions and configuration changes
   • Handles power management and sleep states

2. Web Server (web_server.c)

   • HTTP server for configuration interface
   • REST API endpoints for device control
   • Captive portal for initial setup
   • WebSocket support for real-time updates

3. Network Components

   • RTP Sender (network_out.c): Handles audio streaming to network
   • RTP Receiver (network_in.c): Receives and processes network audio streams
   • mDNS Service: Device discovery and advertisement
   • NTP Client: Time synchronization

4. Audio Interfaces

   • USB Host (usb_out.c): USB DAC output support
   • USB Device (usb_in.c): USB audio capture from host
   • S/PDIF Input (spdif_in.c): Digital audio capture with clock recovery
   • S/PDIF Output (spdif_out.c): Digital audio output

5. Configuration Management

   • Config Manager (config_manager.c): Persistent settings storage
   • WiFi Manager (wifi_manager.c): Network connection management
   • OTA Manager (ota_manager.c): Firmware update handling

INITIALIZING
    ↓
HW_INIT (Hardware initialization, NVS, Power management)
    ↓
STARTING_SERVICES (WiFi, Web server)
    ↓
AWAITING_MODE_CONFIG (Wait for user configuration)
    ↓
[Based on configuration]
    ├── MODE_SENDER_USB
    ├── MODE_SENDER_SPDIF
    ├── MODE_RECEIVER_USB
    └── MODE_RECEIVER_SPDIF

• ESP32-S3 development board
• For USB modes: USB OTG support
• For S/PDIF modes: S/PDIF transceiver hardware
• Optional: BQ25895 battery charger IC
• Optional: TS3USB30ERSWR USB switch

1. Wiring: Connect SPDIF to data pin 17
2. Power On: The device will start in Access Point mode if not configured
3. Connect: Join the WiFi network "ESP32-Scream" (default)
4. Configure: Navigate to http://192.168.4.1 in your browser
5. Setup Wizard: Follow the interactive setup wizard to:
   • Select operating mode
   • Configure network settings
   • Set device name
   • Configure audio parameters

Hold GPIO 0 or GPIO 1 during the first 3 seconds of boot to reset all settings to defaults.

Access the device's IP address in a web browser to access the configuration interface:

• Configuration Tab: Setup wizard and quick configuration
• Logs Tab: Real-time system logs viewer
• System Update Tab: OTA firmware updates
• Import/Export Tab: Backup and restore settings

The device supports automatic discovery through mDNS:

• Service Type: _scream._tcp
• Advertised Properties:
  • Device name
  • IP address
  • Port number
  • Operating mode

Compatible with:

• Scream (Windows)
• PulseAudio RTP
• Generic RTP clients (Pipewire, VLC, etc...)

Firmware updates can be performed through the web interface:

1. Navigate to the "System Update" tab
2. Select or drag the .bin firmware file
3. Click "Start Update"
4. Device will automatically restart after successful update

• Battery charging management
• Power status monitoring
• USB power delivery support

• Protocol: RTP (Real-time Transport Protocol)
• Transport: UDP
• Multicast: Supported
• Discovery: mDNS

• Formats: PCM 16-bit
• Sample Rates: 48kHz
• Channels: Stereo

For a quick and easy way to flash pre-built firmware, you can use the web flash tool:

1. Open Chrome browser and navigate to https://screamrouter.net/esp32-flasher
2. Connect your ESP32 device via USB
3. Follow the on-screen instructions to flash the firmware

• ESP-IDF v5.0 or later
• Python 3.7+

# Clone the repository
git clone https://github.com/your-repo/esp32-rtp
cd esp32-rtp

# Initialize submodules
git submodule update --init --recursive

# Configure the project
idf.py menuconfig

# Build
idf.py build

# Flash to device
idf.py -p /dev/ttyUSB0 flash

# Monitor output
idf.py -p /dev/ttyUSB0 monitor

• Stream audio from PC to HiFi system
• Wireless speaker systems

• Console audio streaming
• Low-latency game audio
• Wireless gaming headsets

1. No Audio Output

   • Check network connectivity
   • Verify port configuration
   • Ensure correct mode selection

2. Audio Dropouts

   • Increase buffer sizes
   • Check WiFi signal strength
   • Reduce network congestion

3. Device Not Discovered

   • Check firewall/AP settings
   • Ensure same network segment