Initial revision

Demo/sgi/al/cmpaf.py

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+# Compare different audio compression schemes.
+#
+# This copies mono audio data from the input port to the output port,
+# and puts up a window with 4 toggle buttons:
+#
+# uLAW       : convert the data to uLAW and back
+# ADPCM      : convert the data to ADPCM and back
+# Difference : make only the difference between the converted and the
+#              original data audible
+# Exit       : quit from the program
+
+import fl
+import FL
+import flp
+import al
+import AL
+import audioop
+import sys
+
+class Cmpaf():
+	def init(self):
+		parsetree = flp.parse_form('cmpaf_form','form')
+		flp.create_full_form(self, parsetree)
+		c = al.newconfig()
+		c.setchannels(AL.MONO)
+		c.setqueuesize(1800)
+		self.iport = al.openport('cmpaf','r', c)
+		self.oport = al.openport('cmpaf','w', c)
+		self.do_adpcm = self.do_ulaw = self.do_diff = 0
+		self.acstate = None
+		self.form.show_form(FL.PLACE_SIZE, 1, 'compare audio formats')
+		return self
+
+	def run(self):
+		while 1:
+			olddata = data = self.iport.readsamps(600)
+			if self.do_ulaw:
+				data = audioop.lin2ulaw(data, 2)
+				data = audioop.ulaw2lin(data, 2)
+			if self.do_adpcm:
+				data, nacstate = audioop.lin2adpcm(data, 2, \
+					  self.acstate)
+				data, dummy = audioop.adpcm2lin(data, 2, \
+					  self.acstate)
+				self.acstate = nacstate
+			if self.do_diff:
+				olddata = audioop.mul(olddata, 2, -1)
+				data = audioop.add(olddata, data, 2)
+			self.oport.writesamps(data)
+			fl.check_forms()
+
+	def cb_exit(self, *args):
+		sys.exit(0)
+
+	def cb_adpcm(self, obj, val):
+		self.do_adpcm = obj.get_button()
+
+	def cb_ulaw(self, obj, val):
+		self.do_ulaw = obj.get_button()
+
+	def cb_diff(self, obj, val):
+		self.do_diff = obj.get_button()
+
+cmpaf = Cmpaf().init()
+cmpaf.run()