(Also note the part about "Flat volumes" below) For recording only the source volume matters. For normal playback first the sink input volume is applied followed by the sink volume. Source outputs do not have a volume attached! In addition a 'mute' boolean is available for the same objects. Sinks, sources and sink inputs have a volume attached. Where possible pa_volume_t is chosen in a way that makes it suitable for showing in UI volume controls mapped linearly to pixels. arithmetic calculations like multiplication, addition, division should not be applied to them. Volumes stored in pa_volume_t/pa_cvolume should be considered opaque, i.e. In some situations volumes > 65536 are possible as well (see below). The values range from 0 (silence) to 65536 ("maximum" sensible volume). In PulseAudio volumes are stored in the pa_volume_t (a single integer) and pa_cvolume (an array of one pa_volume_t integer per channel) data types.
Hence make sure to subscribe to changes in the server and always keep your UI up-to-date. Sinks/sources/sink inputs/source outputs/clients/cards can come and go. Usually this combines one source (for recording) and one sink (for playback) into a single object. Not all sinks/sources must be assigned to a card. Generally we can consider a client to be a collection of sink inputs/source outputs.Ī collection of sinks/sources that belong to a single hardware device. Sink inputs/sources however can also be "unowned", i.e. A sink input/source output can thus be "owned" by a specific client. an output of a source.Īn active client of the PA server, something that can create none/one/many sink inputs/source outputs on any sink/source the PA server has. an input for a sink.Ī stream that is connected to an input device, i.e. Instead it is just a rough list of things you should keep in mind and be aware of.Ī lot of this applies only to PA >= 0.9.19.įor a low-level overview on what is happening underneath read this wiki page! Nomenclatura SinkĪ stream that is connected to an output device, i.e.
For that please consult the doxygen documentation.
This text however does not go into a step-by-step detailed list which API functions you should use to enumerate, manipulate and get information about PA objects. In the following text you'll find a few hints for folks who want to write mixer/volume control type applications for PulseAudio.
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