The Bluetooth-part was taken from oleq
The Bluetooth profile which does the magic is called A2DP.
pi@raspberrypi:~ $ lsusb
...
Bus 001 Device 008: ID 041e:30d3 Creative Technology, Ltd Sound Blaster Play!
...
Bus 001 Device 012: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
...
The on–board audio produces low–quality, noisy output, so I decided to use something better. I chose external USB Creative Sound Blaster Play! interface. It costs ~$20.
As for Bluetooth dongle, I used Digitus Tiny USB-Adapter, which is discovered as Cambridge Silicon Radio, Ltd Bluetooth Dongle.
Note: I used another dongle (different manufacturer) also discovered as Cambridge Silicon Radio but unable to stream audio. So beware, because different manufacturers use the same hardware in a different way. Or they pretend to use the same hardware for some (compatibility?) reasons. This way or another, if you get garbled audio or no audio at all but everything else is alright, don't worry, just try another dongle – it's cheap.
See RPi USB Bluetooth adapters for buying recommendations. Trial and error is another option, since most devices cost below $10.
Raspberry PI offers limited power to USB devices (and limited number of ports). You'll need some active (powered) USB Hub to keep USB devices stable and working (USB Audio, USB Bluettoth and optional USB WiFi). Google to learn more, it's a very common topic when using Raspberry PI.
The setup can be done by hand or by useing a small installation script.
I'm using Raspberry PI 2, running Volumio 2. Make sure your system is up–to–date first:
sudo apt-get update
sudo apt-get upgrade
Note: It usually takes a while. Get some tee and sandwiches.
Then install required packages (related article):
sudo apt-get install alsa-utils bluetooth bluez bluez-tools blueman pulseaudio-module-bluetooth python-gobject python-gobject-2 python
Not quite sure it's really needed (?), but it doesn't hurt:
sudo usermod -a -G lp volumio
Disable PulseAudios "auto spwan":
mkdir -p ~/.config/pulse/
sed 's/; autospawn = yes/autospawn = no/' </etc/pulse/client.conf >~/.config/pulse/client.conf
Use the following configuration to get most of PulseAudio (related article):
volumio@raspberrypi:~ $ sudo nano /etc/pulse/daemon.conf
...
resample-method=ffmpeg
enable-remixing = no
enable-lfe-remixing = no
default-sample-format = s32le
default-sample-rate = 192000
alternate-sample-rate = 176000
default-sample-channels = 2
exit-idle-time = -1
...
Note: PA is pretty CPU–consuming. With the following configuration it uses ~30% of my PI's CPU.
So if you expect PI to do something else beside A2DP and avoid sound glitches, reasearch different resample-method.
Make sure Bluetooth audio is working and discovered as a car audio system (the setup-script will use the hostname as Bluetoothname)
pi@raspberrypi:~ $ sudo nano /etc/bluetooth/main.conf
[General]
Name = volumio
Class = 0x20041C
Enable = Source,Sink,Media,Socket
To automate the Trusting and Connecting process pexpect is needed, so we have to install it by issuing the following commands.
wget https://bootstrap.pypa.io/get-pip.py
sudo python get-pip.py
rm get-pip.py
sudo pip install pexpect
Download the Scripts, I put mine into a folder called a2dp-bluetooth-server.
sudo mkdir -p /usr/bin/a2dp-bluetooth-server
sudo wget https://gist.github.com/ofekp/539ce199a96e6a9ace2c1511cc7409ce/raw/30a91d80d5d7ee93e336f2e9ee1f7e2ef601e3f1/bluetoothctl.py -P /usr/bin/a2dp-bluetooth-server
sudo wget https://raw.githubusercontent.com/karaambaa/a2dp-bluetooth-server/master/a2dp.py -P /usr/bin/a2dp-bluetooth-server
To enable autostarting the service we need to put the following script into /lib/systemd/system and enable the autostart.
sudo wget https://raw.githubusercontent.com/karaambaa/a2dp-bluetooth-server/master/a2dp-server.service -P /lib/systemd/system
sudo chmod 644 /lib/systemd/system/a2dp-server.service
sudo systemctl daemon-reload
sudo systemctl enable a2dp-server.service
sudo systemctl start a2dp-server.service