Pulseaudio blocked the specific device required, and audio playback only worked reliably when using the virtual pulse device. Our workaround for those users was to uninstall pulseaudio.
This of course broke complete desktop audio for these users.
- We wanted this situation to change with XBMC Gotham releases.
Users that run a normal Ubuntu desktop and just use xbmc for normal video & audio playback while also wanting audio in parallel in their browser or pause xbmc, run a game or rhythmbox / Skype or similar now use our new PulseAudio Sink when using XBMC Gotham builds. XBMC only uses pulseaudio because you have installed it and it is running.
1 Multichannel options
PulseAudio will be automatically detected and selected in XBMC when it is running.
If your audio receiver handles AC3, DTS, and EAC3 passthrough then you will need to use a 2.0 channels configuration. Despite the 2.0 setting, audio that has more channels (such as 5.1 or 7.1) will still work as they should.
For other audio receivers, use PCM multichannel and select theoutput either as 5.1 or 7.1.
Systems with PulseAudio will not work with TrueHD or DTS-MA passthrough. The audio will still work in XBMC, but it will not be "bit perfect" unless you use a non-PulseAudio setup.
2 Setting up pavucontrol
2.1 Passthrough Mode
In order to activate Passthrough Codecs, just setup pavucontrol, as in the following:
If you like to do this from the command line, issue:
pactl set-sink-formats 0 "pcm; ac3-iec61937; dts-iec61937; eac3-iec61937"
Where 0 is the sink you want to alter. You can print all sinks, by using:
pactl list sinks
You can leave out the codecs your AVR does not support, always keep pcm.
2.2 Multichannel Mode
To configure instead Multi channel mode, do the following settings.
2.3 Example setup in xbmc
2.4 Guide setup in xbmc
|XBMC Settings||PC Speakers
|TV||AVR SPDIF||AVR HDMI
|Boost volume level on downmix||Enabled||Enabled||Enabled||Enabled||Enabled||Enabled||Enabled|
|Dolby Digital (AC3) capable receiver||N/A||N/A||N/A||Enabled||Disabled||Disabled||Enabled|
|Dolby Digital Plus (E-AC3) capable receiver||N/A||N/A||N/A||Enabled||Disabled||Disabled||Enabled|
|DTS capable receiver||N/A||N/A||N/A||Enabled||Disabled||Disabled||Enabled|
|TrueHD capable receiver||N/A||N/A||N/A||Disabled||Disabled||Disabled||Disabled|
|DTS-HD capable receiver||N/A||N/A||N/A||Disabled||Disabled||Disabled||Disabled|
|Linux / OSX - Output Device Settings|
|Audio output device||Speakers||Speakers||SPDIF/HDMI||SPDIF||HDMI||HDMI||SPDIF|
|Passthrough output device||N/A||N/A||N/A||SPDIF||HDMI||HDMI||SPDIF|
★ Passthrough cannot be selected when Multichannel is enabled...
★★ Passthrough cannot be selected when Multichannel is enabled...
3 Combined Output
If you want to output to all your attached devices in parallel, e.g. HDMI out, analog out and USB sound card, it is enough to add:
load-module module-combine-sink sink_name=combined
to /etc/pulse/default.pa and restart pulseaudio. xbmc will then pickup the device, it is named combined.
4 Audiophile Pulse User
Pulseaudio resamples everything that does not match the underlaying sink, so if you are an audiophile user, you perhaps want to hear your 96 / 192 khz and 24 bit recordings as exact as possible. Therefore you need to tell pulseaudio to use a better resampler in general and second change the default sample rate to 96 or 192 khz. Pulseaudio does not resample audio, that is already in the correct samplerate. Furthermore you need to take care, that your sink has a wide enough output format.
To do this configuration systemwide (96 khz in that example), change /etc/pulse/daemon.conf to include (please replace already existing lines and also remove the commenting):
default-sample-format = s32le default-sample-rate = 96000 resample-method = speex-float-5
The last setting will increase the resample quality from pulse and therefore the CPU load quite a lot. Again: Resampling is only done, when the sink output does not match the data you throw onto it. But as most normal mp3s are in 44.1 khz, you need to take great care when upsampling them. The overwriting of the resample-method is for this use case.
- When would I want Pulseaudio?
- You use your XBMC computer mainly as your Desktop when you don't run XBMC.
- You want other applications audio like Skype, youtube, browser mail notification in parallel with XBMC.
- You use xbmc in windowed mode as Desktop player
- You use Pulseaudio as a network sink to stream Audio to other devices in your living room.
- Passthrough is nice to have for you, but to be honest - you don't really need it.
- Whenever you plugin your Bluetooth headset, xbmc audio will continue over this new device (when Default 'PULSE' device is chosen)
- When would I want ALSA
- You use XBMC as your standalone media center.
- You are highly interested in bitperfect exclusive audio output.
- DTS-HD, TrueHD is something you use daily and is of high importance.
- You don't need other applications that would access audio in parallel.
Why can't I have both?
- Pulseaudio might hogg your Audio device and you cannot open the ALSA device exclusively, therefore we decided for one or the other.
Can I force ALSA, though I have pulseaudio installed and running and know that it will cause problems?
- Yes, you can - start xbmc from terminal with:
- Be warned as this might interfere with your Desktop sounds and pulseaudio!
5.1 Known issues
Whenever the Pulseaudio Sink is unloaded, the stream is completely destructed and created newly. This will reset the stream's volume to the internal xbmc volume. This is only an issue if you use "external volume", e.g. you use pavucontrol and change the stream volume via slider. This only affects the current running stream as xbmc gets no knowledge about it. Best is: use xbmc's internal volume or change the global volume only.
|Linux - Pulseaudio Sink Discussion and further information.|