Struct Audio 

pub struct Audio { /* private fields */ }

Implementations

impl Audio

pub fn new() -> Self

pub fn warm(&mut self)

Starts opening the device if nothing has yet. Cheap to call every frame; the driver calls it once the session holds a sound, so the device is open by the time a click asks for one.

pub fn apply( &mut self, cmds: Vec<AudioCommand>, resources: &SharedResources, ) -> Answered

Applies queued commands to the device. While it is still opening they wait, in order, behind whatever waited before. Returns what the device answered back: the stops that landed on a sound still playing and the plays it would not take, the way Self::poll_ended returns the ones that finished. Both are buffered rather than produced inline, because either can happen inside flush_pending, which runs from the poll as well as from here — so a command that waited for the device reports on the apply that flushes it, a later one than the apply that queued it.

pub fn poll_ended(&mut self) -> Vec<PlaybackId>

Playbacks that finished on their own since the last poll (stopped ones were already forgotten by Stop). Also where a command that waited for the device starts, since the driver polls while anything is active.

pub fn holds_device(&self) -> bool

Whether the device is open (or opening) and so costing something. A CoreAudio/WASAPI/ALSA output stream is a real-time thread that runs whether or not anything is playing — 94 buffer callbacks a second at the usual 512-frame period — which is the whole of an idle kui app’s CPU once a session holds a sound. The driver asks so it knows whether there is anything to close.

pub fn close(&mut self)

Lets the output device go. The decoded-sound cache stays — it is the ~90 ms open that has to be paid again, not the decode — so a re-warm costs nothing a cold start does not. Refuses while anything is playing or waiting, since that is the device’s whole job; the driver only asks after active() has been false for a while.

Asks opening() first, and that is not a detail: a device the app warmed but never commanded stays in Opening forever — nothing else on this type calls opening() unless a command flows — with the opened manager sitting live in the channel and its stream running. That is precisely the case worth closing, so the state has to be settled before it can be read. Still opening means not yet closable; the driver asks again.

pub fn active(&self) -> bool

Whether any playback is live, or waiting on the device to open — drivers keep polling while so. Both answer buffers count: a flush_pending from the poll can fill either, and the core only hears them on the next apply.

pub fn env(&self) -> AudioEnv

The reading a view gets (env.audio): the device’s state and the playbacks started or waiting. The two readers above, as data — what the driver decides by is what the view can see.

Trait Implementations

impl Default for Audio

fn default() -> Self

Returns the “default value” for a type.