Enum GainControlRequest

pub enum GainControlRequest {
    SetGain {
        gain_db: f32,
        control_handle: GainControlControlHandle,
    },
    SetGainWithRamp {
        gain_db: f32,
        duration: i64,
        ramp_type: RampType,
        control_handle: GainControlControlHandle,
    },
    SetMute {
        muted: bool,
        control_handle: GainControlControlHandle,
    },
}

Enables control and monitoring of audio gain. This interface is typically a tear-off of other interfaces. For example, fuchsia.media.audio.Renderer has a BindGainControl method that binds to a gain control that controls gain for the renderer.

Variants

SetGain

Sets the gain in decibels.

Fields

gain_db: f32

control_handle: GainControlControlHandle

SetGainWithRamp

Smoothly changes gain from its current value to specified value, over the specified duration (in milliseconds). If ‘duration_ns’ is 0, gain changes immediately. Otherwise, gain changes only while the stream is running.

Any active or pending ramp is cancelled by subsequent call to SetGain.

There can be at most 1 active ramp at any time. Any active or pending ramp is replaced by a later call to SetGainWithRamp (even if duration is 0). In this case gain would ramps directly from its most recent (mid-ramp) value to the newly-specified one, over the new duration, using the new easing.

Usage example (using time in seconds): Time 0 SetGainWithRamp(MUTED_GAIN_DB, 0, SCALE_LINEAR) // Ramp 1 SetGainWithRamp(0.0f, ZX_SEC(4), SCALE_LINEAR) // Ramp 2 Time 3 PlayNoReply(kNoTimestamp, any_media_time) Time 4 PauseNoReply() Time 7 PlayNoReply(kNoTimestamp, any_media_time) Time 8 SetGainWithRamp(MUTED_GAIN_DB, ZX_SEC(1), SCALE_LINEAR) // Ramp 3

Time 0: Ramp 1 completes immediately, changing the gain to MUTED_GAIN_DB. Ramp 2 is pending, since we are not in playback. Time 3, Ramp 2 begins ramping from MUTED_GAIN_DB to 0 dB (scale 0.0=>1.0). Time 4: Ramp 2 pauses (3s remain). Per SCALE_LINEAR, scale is approx. 0.25. Time 7: Ramp 2 resumes from most recent value toward the target. Time 8: Ramp 3 replaces Ramp 2 and starts from current scale (approx 0.5). Time 9: Ramp 3 completes; current scale value is now 0.0 (MUTED_GAIN_DB).

Fields

gain_db: f32

duration: i64

ramp_type: RampType

control_handle: GainControlControlHandle

SetMute

Sets the mute value. Ramping and mute are fully independent, although they both affect the scaling that is applied.

Fields

muted: bool

control_handle: GainControlControlHandle

Implementations

impl GainControlRequest

pub fn into_set_gain(self) -> Option<(f32, GainControlControlHandle)>

pub fn into_set_gain_with_ramp( self, ) -> Option<(f32, i64, RampType, GainControlControlHandle)>

pub fn into_set_mute(self) -> Option<(bool, GainControlControlHandle)>

pub fn method_name(&self) -> &'static str

Name of the method defined in FIDL

Trait Implementations

impl Debug for GainControlRequest

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.