Lib/lib-stdwin/VUMeter.py

   1 # Module 'VUMeter'
   2
   3 import audio
   4 from StripChart import StripChart
   5
   6 K = 1024
   7 Rates = [0, 32*K, 16*K, 8*K]
   8
   9 class VUMeter(StripChart):
  10         #
  11         # Override define() and timer() methods
  12         #
  13         def define(self, parent):
  14                 self = StripChart.define(self, (parent, 128))
  15                 self.parent.need_timer(self)
  16                 self.sampling = 0
  17                 self.rate = 3
  18                 self.enable(0)
  19                 return self
  20         #
  21         def timer(self):
  22                 if self.sampling:
  23                         chunk = audio.wait_recording()
  24                         self.sampling = 0
  25                         nums = audio.chr2num(chunk)
  26                         ampl = max(abs(min(nums)), abs(max(nums)))
  27                         self.append(ampl)
  28                 if self.enabled and not self.sampling:
  29                         audio.setrate(self.rate)
  30                         size = Rates[self.rate]/10
  31                         size = size/48*48
  32                         audio.start_recording(size)
  33                         self.sampling = 1
  34                 if self.sampling:
  35                         self.parent.settimer(1)
  36         #
  37         # New methods: start() and stop()
  38         #
  39         def stop(self):
  40                 if self.sampling:
  41                         chunk = audio.stop_recording()
  42                         self.sampling = 0
  43                 self.enable(0)
  44         #
  45         def start(self):
  46                 self.enable(1)
  47                 self.timer()