adds Gain node with * operator

src/AudioIO.jl

@@ -19,6 +19,10 @@ abstract AudioNode
 # All AudioStream subtypes should have a mixer and info field
 abstract AudioStream
 
+# An audio interface is usually a physical sound card, but could
+# be anything you'd want to connect a stream to
+abstract AudioInterface
+
 # Info about the hardware device
 type DeviceInfo
     sample_rate::Integer
@@ -28,6 +32,7 @@ end
 include("nodes.jl")
 include("portaudio.jl")
 include("sndfile.jl")
+include("operators.jl")
 
 ############ Exported Functions #############
 

src/nodes.jl

@@ -1,9 +1,8 @@
-export SinOsc, AudioMixer, ArrayPlayer, AudioInput
-
 #### SinOsc ####
 
 # Generates a sin tone at the given frequency
 
+export SinOsc
 type SinOsc <: AudioNode
     active::Bool
     deactivate_cond::Condition
@@ -22,6 +21,26 @@ function render(node::SinOsc, device_input::AudioBuf, info::DeviceInfo)
     return sin(phase), is_active(node)
 end
 
+#### Gain ####
+export Gain
+type Gain <: AudioNode
+    active::Bool
+    deactivate_cond::Condition
+    in_node::AudioNode
+    gain::Float32
+
+    function Gain(in_node::AudioNode, gain::Real)
+        new(false, Condition(), in_node, gain)
+    end
+end
+
+function render(node::Gain, device_input::AudioBuf, info::DeviceInfo)
+    input, child_active = render(node.in_node, device_input, info)
+    # TODO: should we check the active flag of the input?
+    return input .* node.gain, is_active(node)
+end
+
+
 #### AudioMixer ####
 
 # Mixes a set of inputs equally
@@ -30,6 +49,7 @@ end
 typealias MaybeAudioNode Union(AudioNode, Nothing)
 const MAX_MIXER_INPUTS = 32
 
+export AudioMixer
 type AudioMixer <: AudioNode
     active::Bool
     deactivate_cond::Condition
@@ -96,6 +116,7 @@ end
 
 # Plays a AudioBuf by rendering it out piece-by-piece
 
+export ArrayPlayer
 type ArrayPlayer <: AudioNode
     active::Bool
     deactivate_cond::Condition
@@ -154,6 +175,7 @@ end
 
 # Renders incoming audio input from the hardware
 
+export AudioInput
 type AudioInput <: AudioNode
     active::Bool
     deactivate_cond::Condition

src/operators.jl

@@ -0,0 +1,2 @@
+*(node::AudioNode, coef::Real) = Gain(node, coef)
+*(coef::Real, node::AudioNode) = Gain(node, coef)

src/portaudio.jl

@@ -135,7 +135,7 @@ type PaHostApiInfo
     defaultOutputDevice::PaDeviceIndex
 end
 
-type AudioDevice
+type PortAudioInterface <: AudioInterface
     name::String
     host_api::String
     max_input_channels::Int
@@ -152,7 +152,7 @@ function get_portaudio_devices()
     init_portaudio()
     device_count = ccall((:Pa_GetDeviceCount, "libportaudio"), PaDeviceIndex, ())
     pa_devices = [get_device_info(i) for i in 0:(device_count - 1)]
-    [AudioDevice(bytestring(d.name),
+    [PortAudioInterface(bytestring(d.name),
                         bytestring(get_host_api_info(d.host_api).name),
                         d.max_input_channels,
                         d.max_output_channels)