[pulseaudio-discuss] pa_context_set_source_volume_by_index() failed

Tanu Kaskinen tanuk at iki.fi
Wed Oct 26 17:06:18 UTC 2016

On Wed, 2016-10-26 at 18:47 +0200, pfl wrote:
> thanks for the infos, I am gonna check this now
> btw do you have any web page where everything is explained ? sources, 
> sinks, monitors, profiles.... all these

I think this kind of overview is missing. We really should document the
basics properly...

I'll try to give a short summary (for simplicity I'll limit the
explanations to alsa hardware):

Card: A sound card as defined by alsa. There's one-to-one mapping
between cards in pulseaudio and cards in alsa.

Sink: An output device. This corresponds to PCM devices in alsa.

Source: An input device. This corresponds to PCM devices in alsa.

Port: A sink or source may have multiple routing options, and these
options are represented by ports. A typical example is an integrated
sound card on a laptop that provides outputs for the integrated speaker
and the headphone jack. There's only one PCM device, but with mixer
settings the hardware can be configured to use either the speaker or
the headphone output. So the sink in pulseaudio has two ports: one for
speakers and one for headphones. Only one port can be active on a sink
at a time.

Profile: A card often has multiple profiles. Only one profile can be
active at a time. The selected profile defines which sinks and sources
should be made available. For example, the current profile on my
laptop's integrated sound card is output:analog-stereo+input:analog-
stereo, which creates one stereo sink and one stereo source for the
analog output and input. A different profile could for example create a
surround sink instead of stereo (not available on my laptop, though).


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