coreaudio::audio_unit::render_callback::action_flags::PRE_RENDER

pub const PRE_RENDER: ActionFlags = ActionFlags{bits: au::kAudioUnitRenderAction_PreRender,}

Called on a render notification Proc, which is called either before or after the render operation of the audio unit. If this flag is set, the proc is being called before the render operation is performed.

Available in OS X v10.0 and later.