protected override async Task <List <Datum> > PollAsync(CancellationToken cancellationToken)
{
AVAudioRecorder recorder = null;
string recordPath = Path.GetTempFileName();
try
{
AVAudioSession audioSession = AVAudioSession.SharedInstance();
NSError error = audioSession.SetCategory(AVAudioSessionCategory.Record);
if (error != null)
{
throw new Exception("Failed to initialize iOS audio recording session: " + error.LocalizedDescription);
}
error = audioSession.SetActive(true);
if (error != null)
{
throw new Exception("Failed to make audio session active: " + error.LocalizedDescription);
}
recorder = AVAudioRecorder.Create(NSUrl.FromFilename(recordPath), new AudioSettings(_settings), out error);
if (error != null)
{
throw new Exception("Failed to create sound recorder: " + error.LocalizedDescription);
}
recorder.MeteringEnabled = true;
// we need to take a meter reading while the recorder is running, so record for one second beyond the sample length
if (recorder.RecordFor(SampleLengthMS / 1000d + 1))
{
await Task.Delay(SampleLengthMS);
recorder.UpdateMeters();
double decibels = 100 * (recorder.PeakPower(0) + 160) / 160f; // range looks to be [-160 - 0] from http://b2cloud.com.au/tutorial/obtaining-decibels-from-the-ios-microphone
return(new Datum[] { new SoundDatum(DateTimeOffset.UtcNow, decibels) }.ToList());
}
else
{
throw new Exception("Failed to start recording.");
}
}
finally
{
try
{
File.Delete(recordPath);
}
catch (Exception ex)
{
SensusServiceHelper.Get().Logger.Log("Failed to delete sound file: " + ex.Message, LoggingLevel.Debug, GetType());
}
if (recorder != null)
{
try
{
recorder.Stop();
}
catch (Exception) { }
try
{
recorder.Dispose();
}
catch (Exception) { }
}
}
}
