Ubuntu – A2DP on PulseAudio – terrible choppy/skipping audio

bluetoothpulseaudiorealtimesound

I have paired my Bluetooth headset with my Ubuntu 12.04 laptop with a Bluetooth chip inside:

lsusb | grep Bluetooth

Bus 003 Device 003: ID 045e:0745 Microsoft Corp. Nano Transceiver v1.0 for Bluetooth

The device has been paired, and with the help of blueman, I've connected it to PulseAudio as a sink. Audio does come across in A2DP mode, but is terribly choppy and skips to the point of being not much better than nothing.

I read around and saw that there was a fix involving adjusting the nice priority of the PulseAudio server. Since by default, PulseAudio runs on a per-user basis, I added the following to my /etc/security/limits.conf:

*       hard    rtpio   0
*       soft    rtpio   0
@audio  hard    rtpio   20
@audio  soft    rtpio   20
pulse   hard    rtpio   20
pulse   soft    rtpio   20

I then added myself to the audio group to be able to schedule priority for the pulseaudio process. It seems that pulseaudio is now running with a priority of -11:

ps -eo pri,ni,cmd | grep [p]ulse

30 -11 /usr/bin/pulseaudio --start --log-target=syslog

This should mean that PulseAudio is running with a priority of -11, which is good.

However, even after restarting, I still get the terrible choppy audio.

How should I proceed? I'm trying to make this Bluetooth headset I purchased usable.

^{Note: I've tried pairing this device with an Android tablet right next to my laptop and it works fine, so it's not wireless congestion, it seems to be directly correlated to Linux somehow.}

Best Answer

As none of the other answers worked on my system (Ubuntu 18.04 LTS on a 2012 MacBook Air), I found my solution on the german ubuntuusers wiki. English summary of the german instructions:

The choppy output might be caused by the A2DP implementation, and how it buffers sound before encoding it. For me, changing this buffer's size solved the choppy sound problem. You need to perform three steps:

Find necessary info about the bluetooth device (while it is connected!)
```
pactl list | grep -Pzo '.*bluez_card(.*\n)*'
```

The output should be something like

    Name: bluez_card.28_11_A5_84_B6_F9
    Driver: module-bluez5-device.c
    ...
    Ports:
    speaker-output: Speaker (priority: 0, latency offset: 0 usec, available)
        Part of profile(s): a2dp_sink, headset_head_unit
    speaker-input: Bluetooth Input (priority: 0, latency offset: 0 usec, not available)
        Part of profile(s): headset_head_unit

We see that the buffers have currently 0 latency. In the next step, you will need the NAME and PORT of your output. In this example, these are bluez_card.28_11_A5_84_B6_F9 and speaker-output, respectively.

Set the buffer size (latency) of your card to a suitable value with this command pattern:
```
pactl set-port-latency-offset <NAME> <PORT> <BUFFER_SIZE_MICROSECONDS> 
```

The latency unit of the following command is microseconds, so I'm using a 50 millisecond buffer for my command here:

    pactl set-port-latency-offset bluez_card.28_11_A5_84_B6_F9 speaker-output 50000

Restart your bluetooth service to apply your change
```
sudo service bluetooth restart
```

As there is usually no documentation about this, you may have to experiment with higher or lower buffer values. Many people people posted their working latencies in the comments to this answer. Check them out for guidance on the latency value.

Related Solutions

Pulse Audio – How to Debug Pulse Audio Issues

This preliminary answer summarizes steps involved to debug sound available for one user only in an environment where domains were joined for this user. It may need be extended later.

In case we have sound for one user only we may have some bad configuration in this one user account's setting. We need to take the following steps from the affected user account to get further insights into the problem.

Is pulseaudio running at all?
Usually you will see that from having access to the sound menu in the top bar. Alternatively we can issue the following command in a terminal:
```
pulseaudio -k
```
There will be an error in case pulseaudio does not run. In addition this command takes care of stopping and respawning pulseaudio in case it hangs.
Are there wrong user settings for the pulseaudio daemon?
To test this we have to rename the settings directory in the affected user's HOME followed by a restart of pulseaudio (see 1.):
```
mv ~/.pulse ~/.pulse.bad
```
or
```
mv ~/.config/pulse ~/.config/pulse.bad  ## for newer releases
```
Are channels muted from ALSA?
We may open the alsamixer in a terminal to adjust channel volumes, and to unmute a channel in case it was accidentally muted:
```
alsamixer
```
Make sure users are not in the 'audio' group
A user in the audio group has exclusive access to the pulseaudio server. Other users can not access it while this user uses it. Therefore user should not be in the audio group.
Start Pulseaudio manually
In case pulseaudio was not running we can also start the daemon from command line with
```
pulseaudio -D
```
Pulseaudio then uses default settings and starts it's daemon. We can also put this command to our Autostart Applications to overcome the case when pulseaudio fails to run before the desktop was loaded.
Browse log files
Pulseaudio will be loaded on system start up, and on user login. Therefore errors can only be read from a log generating on starting pulseaudio. See this guide on how to generate a pulsaudio log script. In short, we have to take care pulseaudio does not respawn we may run it in verbose mode:
```
pulseaudio -vvvv <options>
```

_{to be completed}

In the case given in the question we could see that pulseaudio fails to run because it was unable to start the D-Bus service. This may likely be caused by a broken or overlong path to the user's HOME (see bug #872992). As a workaround we may issue pulseaudio without D-Bus control by commenting out the following line in /etc/pulse/default.pa like this:

# load-module module-dbus-protocol

However then we (and our applications) will not be able to control pulseaudio using D-Bus.

Ubuntu – Bluetooth profile locked to A2DP (high-quality audio sink) but cannot change to HFP/HSP (low-quality bidirectional headset)

EDIT: also try connecting using Blueman. I don't know why PulseAudio has so much trouble but simply opening Blueman, right-clicking on my headphones in the overview, and selecting Audio Profile > Headset Head Unit (HSP/HFP) fixed it for me. I have since stopped and removed oFono and it still seems to work.

I had a similar (the same?) problem with my Bose QC35 II and fixed it by following these instructions ("Using HFP with oFono").

I'm on Debian buster so things might be a little bit different for you.

Install ofono and ofono-phonesim:
```
sudo apt-get install ofono-phonesim
```

Clone the oFono Git repository (currently at cf850de632):

git clone git://git.kernel.org/pub/scm/network/ofono/ofono.git
cd ofono

List the available modems you have:
```
./test/list-modems
```
It'll probably have no modems, which is not surprising on a modern Linux desktop. But for reasons I don't really understand you really do need to have some sort of modem to get headphones to work, so we're going to simulate one now.
Start by simulating one (you can probably pick a different port if you want):
```
ofono-phonesim -p 12345 /usr/share/phonesim/default.xml
```
Modify /etc/ofono/phonesim.conf to use this simulated modem. My Debian version was so kind to put something in there already but commented it out. This is what it looks like for me now (without the comments):
```
[phonesim]
Driver=phonesim
Address=127.0.0.1
Port=12345
```
Restart oFono:
```
sudo service ofono restart
```
Check that the device is now listed:
```
./test/list-modems
```

Enable the device:

./test/enable-modem /phonesim

If you get an error like this, make sure your phonesim is up and running:

Connecting modem /phonesim...
Traceback (most recent call last):
  File "./test/enable-modem", line 20, in <module>
    modem.SetProperty("Powered", dbus.Boolean(1), timeout = 120)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.ofono.Error.Failed: Operation failed

Check that the device is now powered on using ./test/list-modems.

Hopefully it works now! You may need to restart other services too (bluez, pulseaudio).

I can now pick my headphone as an input device. It will cause the device to use very low quality audio but at least it works. Make sure to switch back to "High Fidelity Playback (A2DP Sink)" when you're done with the microphone as you'll otherwise get very low quality audio output.