A2DP Sink on Ubuntu Linux with bluez (streaming bluetooth stereo audio from smartphone to pc)

a2dp_sink_ubuntu_linux.md

Howto Enable and Use A2DP Sink on Ubuntu Linux with Bluez

1. Add Enable=Source to /etc/bluetooth/audio.conf right after [General].

2. Find address in form XX:XX:XX:XX:XX:XX of phone with hcitool scan.

3. Pair and trust smartphone with sudo bluez-simple-agent hci0 XX:XX:XX:XX:XX:XX and sudo bluez-test-device trusted XX:XX:XX:XX:XX:XX yes.

4. Create loopback in pulseaudio connection bluetooth a2dp source with alsa sink:

pactl load-module module-loopback \
source=bluez_source.XX_XX_XX_XX_XX_XX \
sink=alsa_output.pci-0000_00_1b.0.analog-stereo

You can find your own values for source and sink with pacmd list-sources and pacmd list-sinks.

Thank you a lot for this little Gist. It worked immediatly on my Ubuntu 12.04 setup at work ! All the other tutorials and documentations on the subject failed on my machine.

To automatically do #4, when device is connected, I have this script running (before connecting, it needs to receive the event).

#!/usr/bin/python

# based on monitor-bluetooth
# Changes by Domen Puncer <[email protected]>

import gobject
import dbus
import dbus.mainloop.glib
import os


# we want this event: {AudioSource.PropertyChanged} [/org/bluez/16797/hci0/dev_00_24_7E_51_F7_52] State = playing
# and when that happens: pactl load-module module-loopback source=bluez_source.00_24_7E_51_F7_52 sink=alsa_output.pci-0000_00_1b.0.analog-stereo
def property_changed(name, value, path, interface):
    iface = interface[interface.rfind(".") + 1:]
    val = str(value)
    print "{%s.PropertyChanged} [%s] %s = %s" % (iface, path, name, val)
    if iface == "AudioSource" and name == "State" and val == "playing":
        bt_addr = "_".join(path.split('/')[-1].split('_')[1:])
        cmd = "pactl load-module module-loopback source=bluez_source.%s sink=alsa_output.pci-0000_00_1b.0.analog-stereo" % bt_addr
        os.system(cmd)


def object_signal(value, path, interface, member):
    iface = interface[interface.rfind(".") + 1:]
    val = str(value)
    print "{%s.%s} [%s] Path = %s" % (iface, member, path, val)

if __name__ == '__main__':
    dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)

    bus = dbus.SystemBus()

    bus.add_signal_receiver(property_changed, bus_name="org.bluez", signal_name = "PropertyChanged", path_keyword="path", interface_keyword="interface")

    mainloop = gobject.MainLoop()
    mainloop.run()

@domenpuncer I've modified your python script to remove the loopback module when the device disconnects. If the module is kept loaded, it can cause some nasty feedback.

Gist is here: https://gist.github.com/dghodgson/8406352

Unfortunately I'm not very familiar with python, or dbus's python interface, so my solution is a bit of a hack. It just checks for a dbus message which consistently pops up when the device connects, and runs a shell command that removes all loopback modules for that device. Kind of ugly, but it seems to work reliably for me.

I updated the script with a fix for the issue where multiple loopback modules would get loaded with successive pausing/playing of an audio stream.

Is it possible to change the code in a way that will allow streaming audio from iPhone to Linux?

When I ran this code on Ubuntu 14.04, and connected an iPhone via bluetooth to the Ubuntu box, I got the following two lines:
{HandsfreeGateway.PropertyChanged} [/org/bluez/27095/hci0/dev_00_34_5E_22_F5_61] State = connecting
{HandsfreeGateway.PropertyChanged} [/org/bluez/27095/hci0/dev_00_34_5E_22_F5_61] State = disconnected

Thanks so mcuh for this script and thanks domenpuncer and Toasty27 for your improvements!
I wrote my own little Gist (https://gist.github.com/boulund/8949499e17493e1c00db) explaining all the steps I had to take to get it working on my Debian server (mainly for my own memory, should I ever need to redo it).

When I tried this, I found the following two sinks:

$ pacmd list-sinks | grep name:
name: <alsa_output.pci-0000_01_00.1.hdmi-stereo>
name: <alsa_output.pci-0000_00_1b.0.iec958-stereo>

However, both failed the same way:

$ pactl load-module module-loopback source=bluez_source.7C:6D:62:6B:85:68 sink=alsa_output.pci-0000_01_00.1.hdmi-stereo
Failure: Module initialization failed

What am I missing?

How would I pair automatically? Example - I want to run the system on a HTPC device, so it should pretend to be A2DP headphones and start playback from any phone which asks for connection.

I get Failure: Module initialization failed when running this on 16.10 unfortunately.

@csvan check your pactl list. alsa module name is changed.
In my case, I using sink=alsa_output.pci-0000_00_1f.4.analog-stereo.

pactl list | grep Name:
...
Name: alsa_output.pci-0000_00_1f.4.analog-stereo
...

Worked like a charm on my arch i3 box!! Thanks a lot for this!

Thanks a lot, also working on my zotac zbox with kaby lake processor and ubuntu 16.04 LTS :)

It did not work with me on raspberry pi

What does " pacmd list-sources | grep name: " produce?

Does your bluez source have .a2dp_source on the end of the name? I think there's a typo in the original post although things may have changed since then. My machine gives:

test@test:~$ pacmd list-sources | grep name:
        name: <alsa_output.pci-0000_00_05.0.analog-stereo.monitor>
        name: <alsa_input.pci-0000_00_05.0.analog-stereo>
        name: <bluez_source.94_7B_E7_XX_XX_XX.a2dp_source>

So I need

pactl load-module module-loopback source=bluez_source.94_7B_E7_XX_XX_XX.a2dp_source sink=alsa_output.pci-0000_00_05.0.analog-stereo

I'm not getting output but at least the loopback loads without error.

Edit: This worked for me:
https://gist.github.com/oleq/24e09112b07464acbda1#gistcomment-2175574