High-fidelity Bluetooth audio receiver with premium codec support
_{LDAC | aptX HD | aptX | AAC | SBC}

Updated version built on ESP-IDF v5.5.2 with native multi-codec decoding
View original ESP-IDF 5.1.4 version

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Table of Contents

• Features
• Supported Codecs
• Hardware Requirements
• Repository Structure
• Building from Source
• OTA Updates
• BLE GATT Services
• Configuration
• Troubleshooting
• Credits
• License

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Features

Audio Processing

• Hi-Res LDAC streaming up to 96kHz/24-bit
• aptX HD/aptX/aptX-LL for low latency
• AAC for Apple device compatibility
• LC3plus and Opus codec support
• Real-time DSP processing with optimized biquad filters
• 3-band parametric EQ (bass, mid, treble)
• Stage Presence 3D audio enhancement with bass centering and stereo widening
• Division-free DSP using fast reciprocal approximations for ESP32 optimization

Visual Feedback

• 16x16 LED Matrix with SPI/DMA driver
• 24 audio-reactive LED effects including spectrum analyzer, VU meter, fire, plasma, starfield, rainbow patterns, and more
• Audio AGC (Automatic Gain Control) with fixed floor normalization for LED reactivity at all volume levels
• Volume/EQ overlay display
• Pairing mode LED animation
• Startup animation with fixed brightness

Hardware Control

• Quad Rotary Encoder support (Adafruit 5752)
• Volume, Bass, Mid, Treble controls
• LED effect selection via encoder
• Brightness adjustment mode
• Multi-click detection (play/pause/next/prev)

Connectivity

• BLE GATT remote control
• Real-time level meters
• OTA firmware updates via BLE or Android app
• Encrypted OTA with AES-256-CBC
• WiFi OTA Recovery system

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Supported Codecs

Codec	Bitrate	Sample Rate	Latency	Use Case
LDAC	990 kbps	96 kHz	~200ms	Hi-Res listening
aptX HD	576 kbps	48 kHz	~150ms	High quality
aptX	352 kbps	48 kHz	~120ms	CD quality
aptX-LL	352 kbps	48 kHz	~40ms	Gaming/Video
AAC	256 kbps	44.1 kHz	~150ms	Apple devices
LC3plus	Variable	48 kHz	~20ms	BT LE Audio
Opus	Variable	48 kHz	~20ms	Open codec
SBC	328 kbps	44.1 kHz	~200ms	Universal

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Hardware Requirements

Component	Requirement	Notes
MCU	ESP32-WROVER or ESP32-WROOM	Original ESP32 only (not S2/S3/C3)
PSRAM	Optional (8MB recommended)	Enables larger buffers for LDAC/AAC
Flash	8MB	Enables OTA dual partition
DAC	I2S compatible	PCM5102, MAX98357A, etc.
Encoder	Adafruit Quad Rotary (5752)	Optional - I2C control interface
LED Matrix	16x16 WS2812B	Optional - SPI/DMA driven

GPIO Assignments

GPIO	Function
GPIO 25	I2S DATA
GPIO 26	I2S BCK
GPIO 27	I2S LRCK
GPIO 18	LED Matrix Data
GPIO 23	I2C SDA (Encoder)
GPIO 22	I2C SCL (Encoder)

Quad Rotary Encoder (Adafruit 5752)

Encoder	Function	Button Action
Volume (Green)	Adjust volume	1-click: Play/Pause, 2-click: Next, 3-click: Previous
Bass (Red)	Adjust bass EQ	Click: Enter brightness mode
Mid (Blue)	Adjust mid EQ	Click: Enter Bluetooth pairing mode
Treble (Yellow)	Adjust treble EQ	Click: Enter effect selection mode

PSRAM vs Non-PSRAM Mode

Mode	Audio Buffers	OTA Buffer	LED Stack	Best For
With PSRAM	48 x 8KB (384KB)	16KB	8KB	LDAC 96kHz, AAC
Without PSRAM	16 x 2KB (32KB)	4KB	4KB	SBC, aptX

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Repository Structure

ESP32-A2DP-SINK-WITH-CODECS-UPDATED/
├── README.md                 # This file
├── bt_audio_sink/            # Main ESP32 project
│   ├── main/                 # Application source code
│   ├── components/           # ESP32-A2DP, arduino-audio-tools
│   ├── recovery/             # OTA recovery partition
│   └── tools/                # Firmware encryption tools
└── esp-idf/                  # ESP-IDF v5.5.2 with patched Bluetooth stack

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Building from Source

Step 1: Clone This Repository

git clone https://github.com/WillyBilly06/ESP32-A2DP-SINK-WITH-CODECS-UPDATED.git
cd ESP32-A2DP-SINK-WITH-CODECS-UPDATED

Step 2: Set Up ESP-IDF Environment

Windows:

cd esp-idf
install.bat
export.bat

Linux/macOS:

cd esp-idf
./install.sh
. ./export.sh

Step 3: Build and Flash

Windows:

cd ..\bt_audio_sink
idf.py build
idf.py -p COMXX (Replace this with your ESP32 COM) flash monitor

Linux/macOS:

cd ../bt_audio_sink
idf.py build
idf.py -p /dev/ttyUSB0 flash monitor

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OTA Updates

The firmware supports encrypted OTA updates via Google Drive.

OTA Performance

Metric	Value
Firmware Size	~1,320 KB
Download + Flash Time	~1 minute 10 seconds
Encryption	AES-256-CBC

Encrypting Firmware for OTA

1. Generate a new AES key:

cd bt_audio_sink/tools
python encrypt_firmware.py --generate-key

2. Update the key in:

   • tools/encrypt_firmware.py (AES_KEY variable)
   • recovery/main/recovery_main.cpp (AES_KEY array)

3. Build and encrypt:

idf.py build
python tools/encrypt_firmware.py build/bt_audio_sink.bin --version 1.1.0

4. Upload ota_releases/1.1.0.enc to Google Drive and share with "Anyone with link"

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BLE GATT Services

Control your audio device remotely via Bluetooth Low Energy:

Service	UUID Prefix	Description
Level Meters	0x0042	Real-time L/R audio levels (0-80)
Control	0x0046	Play, Pause, Volume, Mute
Equalizer	0x0048	Bass, Mid, Treble (-12 to +12 dB)
Device Name	0x0050	Read/write Bluetooth device name
OTA Control	0x0054	Firmware update control
OTA Data	0x0056	Firmware binary transfer
LED Control	0x0058	Effect selection, brightness

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Configuration

Key sdkconfig settings for optimal performance:

# Flash and Memory
CONFIG_ESPTOOLPY_FLASHSIZE_8MB=y
CONFIG_ESPTOOLPY_FLASHFREQ_80M=y
CONFIG_SPIRAM_SPEED_80M=y

# CPU Performance
CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240=y

# Bluetooth Codecs (built into patched ESP-IDF 5.5.2)
CONFIG_BTDM_CTRL_MODE_BTDM=y
CONFIG_BT_A2DP_ENABLE=y
CONFIG_BT_A2DP_LDAC_DECODER=y
CONFIG_BT_A2DP_APTX_DECODER=y
CONFIG_BT_A2DP_AAC_DECODER=y
CONFIG_BT_A2DP_OPUS_DECODER=y
CONFIG_BT_A2DP_LC3PLUS_DECODER=y

DSP Configuration

The DSP processor includes:

• 3-band Parametric EQ: Bass (80Hz), Mid (1kHz), Treble (8kHz)
• Stage Presence 3D: Bass frequencies (<180Hz) centered mono, mids/highs widened 2.2x
• LED Audio Boost: Up to 100x gain for low volume LED reactivity
• Fast Math: Division-free operations using hardware reciprocal approximations

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Troubleshooting

Bluetooth pairing issues on Linux

Clear the Bluetooth cache:

sudo rm -rf /var/lib/bluetooth/<adapter-mac>/cache/<device-mac>

Then re-pair the device.

LED effects not reactive at low volume

The firmware includes automatic gain control that boosts audio to 70% minimum for LED effects. If LEDs still don't react, check the LED matrix wiring and GPIO configuration.

AAC decoder fails to initialize

Ensure PSRAM is enabled and running at 80MHz. Check that your ESP32 board has PSRAM (WROVER, not WROOM).

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Credits

This project builds upon the excellent work of the open-source community:

Project	Author	Description
ESP32-A2DP	cfint/pschatzmann	A2DP library
arduino-audio-tools	cfint/pschatzmann	Audio Processing
libldac-dec	cfint	LDAC decoder
libfreeaptx-esp	cfint	aptX decoder for ESP32
ESP-IDF	Espressif	Official ESP32 development framework
Original Project	WillyBilly06	ESP-IDF 5.1.4 version

Codec Libraries (integrated into patched ESP-IDF)

• libldac-dec - LDAC decoder
• libfreeaptx - aptX/aptX-HD decoder
• LibHelix-AAC - AAC decoder
• libopus - Opus decoder
• liblc3 - LC3 decoder

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License

This project is licensed under the MIT License - see the LICENSE file for details.