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1 # based on http://freshfoo.com/blog/pulseaudio_monitoring
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2 from __future__ import division
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3 import socket, argparse
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4 from Queue import Queue
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5 from ctypes import POINTER, c_ubyte, c_void_p, c_ulong, cast
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6 import galena
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7
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8 # From https://github.com/Valodim/python-pulseaudio
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9 from pulseaudio import lib_pulseaudio as P
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10
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11 METER_RATE = 1
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12 MAX_SAMPLE_VALUE = 127
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13
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14 class PeakMonitor(object):
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15
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16 def __init__(self, source_name, rate):
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17 self.source_name = source_name
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18 self.rate = rate
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19
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20 # Wrap callback methods in appropriate ctypefunc instances so
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21 # that the Pulseaudio C API can call them
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22 self._context_notify_cb = P.pa_context_notify_cb_t(self.context_notify_cb)
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23 self._source_info_cb = P.pa_source_info_cb_t(self.source_info_cb)
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24 self._stream_read_cb = P.pa_stream_request_cb_t(self.stream_read_cb)
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25
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26 # stream_read_cb() puts peak samples into this Queue instance
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27 self._samples = Queue()
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28
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29 # Create the mainloop thread and set our context_notify_cb
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30 # method to be called when there's updates relating to the
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31 # connection to Pulseaudio
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32 _mainloop = P.pa_threaded_mainloop_new()
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33 _mainloop_api = P.pa_threaded_mainloop_get_api(_mainloop)
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34 context = P.pa_context_new(_mainloop_api, 'peak_demo')
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35 P.pa_context_set_state_callback(context, self._context_notify_cb, None)
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36 P.pa_context_connect(context, None, 0, None)
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37 P.pa_threaded_mainloop_start(_mainloop)
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38
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39 def __iter__(self):
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40 while True:
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41 yield self._samples.get()
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42
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43 def context_notify_cb(self, context, _):
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44 state = P.pa_context_get_state(context)
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45
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46 if state == P.PA_CONTEXT_READY:
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47 print "Pulseaudio connection ready..."
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48 # Connected to Pulseaudio. Now request that source_info_cb
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49 # be called with information about the available sources.
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50 o = P.pa_context_get_source_info_list(context, self._source_info_cb, None)
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51 P.pa_operation_unref(o)
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52
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53 elif state == P.PA_CONTEXT_FAILED :
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54 print "Connection failed"
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55
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56 elif state == P.PA_CONTEXT_TERMINATED:
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57 print "Connection terminated"
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58
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59 def source_info_cb(self, context, source_info_p, _, __):
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60 if not source_info_p:
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61 return
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62
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63 source_info = source_info_p.contents
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64
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65 if source_info.name == self.source_name:
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66 # Found the source we want to monitor for peak levels.
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67 # Tell PA to call stream_read_cb with peak samples.
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68 print 'setting up peak recording using', source_info.name
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69 print 'description:', source_info.description
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70 samplespec = P.pa_sample_spec()
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71 samplespec.channels = 1
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72 samplespec.format = P.PA_SAMPLE_U8
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73 samplespec.rate = self.rate
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74
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75 pa_stream = P.pa_stream_new(context, "peak detect demo", samplespec, None)
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76 P.pa_stream_set_read_callback(pa_stream,
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77 self._stream_read_cb,
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78 source_info.index)
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79 P.pa_stream_connect_record(pa_stream,
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80 source_info.name,
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81 None,
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82 P.PA_STREAM_PEAK_DETECT)
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83
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84 def stream_read_cb(self, stream, length, index_incr):
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85 data = c_void_p()
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86 P.pa_stream_peek(stream, data, c_ulong(length))
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87 data = cast(data, POINTER(c_ubyte))
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88 for i in xrange(length):
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89 # When PA_SAMPLE_U8 is used, samples values range from 128
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90 # to 255 because the underlying audio data is signed but
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91 # it doesn't make sense to return signed peaks.
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92 self._samples.put(data[i] - 128)
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93 P.pa_stream_drop(stream)
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94
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95 def main():
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96
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97
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98 parser = argparse.ArgumentParser()
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99 parser.add_argument(
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100 '--source', required=True,
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101 help='pulseaudio source name (use `pactl list sources | grep Name`)')
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102
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103 args = parser.parse_args()
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104
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105
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106 out = galena.Galena(host='bang')
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107 prefix = 'system.house.audio.%s' % socket.gethostname()
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108 monitor = PeakMonitor(args.source, METER_RATE)
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109 for sample in monitor:
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110 #print ' %3d %s' % (sample, '>' * sample)
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111 out.send(prefix + ".max", sample / 128)
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112
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113 if __name__ == '__main__':
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114 main()
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