LDAC decoder

this is an early stage, jet functional LDAC audio stream decoder.

Shout-out to @Thealexbarney for the heavy lifting. LDAC is basically a stripped down, streaming only ATRAC9.

Build

sudo apt install libsndfile1 libsndfile1-dev libsamplerate0 libsamplerate0-dev
make libldacdec.so
sudo make install

Usage

see ldacdec.c for example usage

ldacdec

takes an LDAC stream and decodes it to WAV

ldacenc

uses Android LDAC encoder library to create LDAC streams from audio

Build BlueALSA with support for this library:

LDAC_INCLUDE_DIR=/usr/include/ldac
LDAC_LIB_DIR=/usr/lib

export LDAC_ABR_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_ABR_LIBS="-L$LDAC_LIB_DIR -lldacBT_abr"
export LDAC_DEC_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_DEC_LIBS="-L$LDAC_LIB_DIR -lldacdec"
export LDAC_ENC_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_ENC_LIBS="-L$LDAC_LIB_DIR -lldacBT_enc"


autoreconf --install
mkdir build && cd build
../configure --enable-aac --enable-ofono --enable-aptx --enable-aptx-hd --with-libopenaptx --enable-ldac --enable-debug
make
sudo make install

Building for Raspberry Pi

Apply the following patch to your kernel

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index eebe25610..64db1db3f 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1825,7 +1825,7 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
                        break;
                }
 
-               chan->imtu = L2CAP_DEFAULT_MTU;
+               chan->imtu = 0;
                chan->omtu = 0;
                if (!disable_ertm && sk->sk_type == SOCK_STREAM) {
                        chan->mode = L2CAP_MODE_ERTM;

If you're running a Debian-based system, you can also run this script to patch and build the kernel, with this command:

# If you have cloned the repository
./patch-kernel.sh --install

# If you havent't cloned the repository
curl https://raw.githubusercontent.com/anonymix007/libldacdec/master/patch-kernel.sh | bash -s -- --install

If you want to add additional configurations to the kernel, you can pass --configure. If you don't want to install the kernel, but you just want to compile it, you can remove --install from the command.

Run the following script to automatically build and install bluez-alsa with LDAC decoding capabilities:

#!/bin/sh

sudo apt install -y git automake build-essential libtool pkg-config python3-docutils
sudo apt install -y libasound2-dev libbluetooth-dev libdbus-1-dev libglib2.0-dev libsbc-dev
sudo apt install -y check libfdk-aac-dev lcov libldacbt-enc-dev libldacbt-abr-dev libbsd-dev libopenaptx-dev libunwind-dev libncurses-dev libreadline-dev libspandsp-dev libsndfile1 libsndfile1-dev libsamplerate0 libsamplerate0-dev

git clone https://github.com/anonymix007/libldacdec.git
cd libldacdec
make libldacdec.so
sudo make install
cd

git clone https://github.com/Arkq/bluez-alsa.git
cd bluez-alsa
LDAC_INCLUDE_DIR=/usr/include/ldac
LDAC_LIB_DIR=/usr/lib
export LDAC_ABR_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_ABR_LIBS="-L$LDAC_LIB_DIR -lldacBT_abr"
export LDAC_DEC_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_DEC_LIBS="-L$LDAC_LIB_DIR -lldacdec"
export LDAC_ENC_CFLAGS="-I$LDAC_INCLUDE_DIR"
export LDAC_ENC_LIBS="-L$LDAC_LIB_DIR -lldacBT_enc"
autoreconf --install --force
mkdir build && cd build
../configure --enable-aac --enable-aptx --enable-aptx-hd --with-libopenaptx --enable-ldac --enable-debug --enable-cli
make -j4
sudo make install