Setup espeak TTS. Fix "velocity" -> "gain".

I was originally thinking the velocity sensor would adjust the midi note velocity.
The downside to this is that you have to wait for a note to play to "feel" the volume change.

When changed to alter the gain of the synth itself, it is much smoother -- works for any
sound, even those that have already started playing.

FossilOrigin-Name: 9b5a893d5b6e3aed1e11d0b984b5f498d9b67f55cda304bbef4179944ca6260f

theremin/lib/theremin.rb

@@ -7,6 +7,7 @@ require 'configurability'
 require 'loggability'
 require 'gpio'
 require 'fluidsynth'
+require 'open3'
 
 
 # A class that coordinates GPIO events and translates
@@ -52,14 +53,14 @@ class Theremin
  		end
  
  		##
- 		# The GPIO pin the velocity trigger is on.
- 		setting :velocity_trigger do |val|
+ 		# The GPIO pin the gain trigger is on.
+ 		setting :gain_trigger do |val|
  			GPIO.new( val ) if val
  		end
  
  		##
- 		# The GPIO pin the velocity echo measurement is on.
- 		setting :velocity_echo do |val|
+ 		# The GPIO pin the gain echo measurement is on.
+ 		setting :gain_echo do |val|
  			GPIO.new( val ) if val
  		end
 
@@ -85,7 +86,7 @@ class Theremin
 
 		##
 		# Initial synth volume.
-		setting :gain, default: 1.0
+		setting :gain, default: 0.0
 
 		##
 		# Enable reverb?
@@ -128,12 +129,14 @@ class Theremin
 	### Instance a new Theremin daemon.
 	###
 	def initialize
-		@pins    = %i[ pitch_trigger pitch_echo velocity_trigger velocity_echo ]
-		@timeout = 0
-		@synth   = FluidSynth.new( self.class.host, self.class.port )
-		@running = false
-		@threads = []
+		@pins      = %i[ pitch_trigger pitch_echo gain_trigger gain_echo ]
+		@timeout   = 0
+		@synth     = FluidSynth.new( self.class.host, self.class.port )
+		@speech_io = nil
+		@running   = false
+		@threads   = []
 
+		self.setup_speech
 		self.setup_gpio
 
 	rescue => err
@@ -150,6 +153,9 @@ class Theremin
 	# The Fluidsynth instance.
     attr_reader :synth
 
+	# An IO to stream to espeak.
+    attr_reader :speech_io
+
 	# Is this Theremin currently running?
     attr_reader :running
 
@@ -169,8 +175,9 @@ class Theremin
 		self.instrument( self.class.font_index, self.class.instrument_index )
 
 		@threads << self.note_thread
-		@threads << self.velocity_thread
+		@threads << self.gain_thread
 		self.led( :green )
+		self.speak "Hi.  I'm Maude."
 		self.log.warn "Waiting for interaction, or ctrl-c to exit."
 		@threads.map( &:join )
 	end
@@ -182,6 +189,7 @@ class Theremin
 		@running = false
 		self.pins.each {|pin| self.class.send( pin ).unexport rescue nil }
 		self.synth.socket.close
+		self.speech_io.close if self.speech_io && !self.speech_io.closed?
 		self.led( :red )
 	end
 
@@ -230,25 +238,25 @@ class Theremin
 	end
 
 
-	### Measure velocity distance, convert for synth notes.
+	### Measure gain distance, convert for any playing notes.
 	###
-	def velocity_thread
-		self.log.info "Starting velocity measurements (every %s/sec) within %d feet." % [
+	def gain_thread
+		self.log.info "Starting gain measurements (every %s/sec) within %d feet." % [
 			self.class.sample_interval,
 			self.class.distance_max
 		]
 
 		return self.running_thread do
-			distance = self.distance( :velocity )
-			velocity = self.distance_to_velocity( distance )
+			distance = self.distance( :gain )
+			gain = self.distance_to_gain( distance )
 
 			# Only set if within maximum distance.
 			#
 			if distance > 0 && distance <= self.class.distance_max
-				self.log.debug "Velocity distance %0.2f (velocity %s)" % [ distance, velocity ]
-				synth.velocity = velocity
+				self.log.debug "Gain distance %0.2f (gain %s)" % [ distance, gain ]
+				synth.gain( gain )
 			else
-				synth.velocity = 0
+				synth.gain( 0 )
 			end
 
 			sleep self.class.sample_interval
@@ -256,6 +264,15 @@ class Theremin
 	end
 
 
+	### Open a pipe to espeak, and wait on input.
+	## 
+	def setup_speech
+		self.log.info "Starting background espeak process."
+		cmd = %w[ espeak -k20 -v f5 -s 160 -a 150 ]
+		@speech_io, stdout, stderr, wait_thr = Open3.popen3( *cmd )
+	end
+
+
 	### Create a new thread loop that returns when @running is false.
 	###
 	def running_thread( &block )
@@ -278,11 +295,11 @@ class Theremin
 		end
 
 		self.class.pitch_trigger.mode( :out )
-		self.class.velocity_trigger.mode( :out )
+		self.class.gain_trigger.mode( :out )
 		self.class.pitch_echo.mode( :in )
 		self.class.pitch_echo.edge( :both )
-		self.class.velocity_echo.mode( :in )
-		self.class.velocity_echo.edge( :both )
+		self.class.gain_echo.mode( :in )
+		self.class.gain_echo.edge( :both )
 	end
 
 
@@ -295,23 +312,22 @@ class Theremin
 		distance_min = 0
 
 		slope = 1.0 * ( midi_end - midi_start ) / ( self.class.distance_max - distance_min )
-		return midi_start + ( slope * ( distance - distance_min ) ).round
+		return ( midi_start + ( slope * ( distance - distance_min ) ) ).round
 	end
 
 
-	### For a given +distance+ in feet, convert into a velocity range (0-127).
+	### For a given +distance+ in feet, convert into a gain range (0-5).
 	###
-	def distance_to_velocity( distance )
-		velocity_start = 127
-		velocity_end   = 1
-		distance_min   = 0
+	def distance_to_gain( distance )
+		gain_start   = 5.0
+		gain_end     = 0.0
+		distance_min = 0
 
-		slope = 1.0 * ( velocity_end - velocity_start ) / ( self.class.distance_max - distance_min )
-		return velocity_start + ( slope * ( distance - distance_min ) ).round
+		slope = 1.0 * ( gain_end - gain_start ) / ( self.class.distance_max - distance_min )
+		return ( gain_start + ( slope * ( distance - distance_min ) ) ).round( 2 )
 	end
 
 
-
 	### Returns detected distance in feet for a given +device+.
 	###
 	def distance( device )
@@ -358,5 +374,12 @@ class Theremin
 		end
 	end
 
+
+	### Send text to the speech engine.
+	###
+	def speak( phrase )
+		self.speech_io.puts( phrase )
+	end
+
 end # class Theremin