/// <summary>
/// Finds the non-speech regions in audio data based on zero-crossing rate and energy descriptors
/// </summary>
/// <param name="waveform">Wavefrom to get spaces from.</param>
/// <returns>spaces</returns>
public static List<Space> FindSpaces(Waveform waveform)
{
var spaces = new List<Space>();
float waveDurationSeconds = (waveform.Header.DataSize) / ((float)waveform.Header.ByteRate);
int ratio = waveform.Header.Channels == 2 ? 40 : 80;
double samplesPerSecond = waveform.Header.SampleRate * (waveform.Header.BlockAlign / (double)ratio);
//keeps track of sounds descriptors for each window
var zcrHistogram = new List<float>();
var energyHistogram = new List<float>();
const int windowSize = 1; // 1 SECOND
//do through each window and calculate the audio descriptors
for (int window = 0; window < waveDurationSeconds; window++)
{
var start = (int)Math.Round(window * (windowSize * samplesPerSecond));
if (start + samplesPerSecond < waveform.Data.Count)
{
List<short> bin = waveform.Data.GetRange(start, (int)samplesPerSecond); //section of the audio waveform.Data
zcrHistogram.Add(Zcr(bin));
energyHistogram.Add(Energy(bin));
}
}
const double zcrFactor = 0.80;
const double energyFactor = 0.4;
double zcrAvg = zcrFactor * zcrHistogram.Average();
double energyAvg = energyFactor * energyHistogram.Average();
//decide if a window should be marked as speech or not
for (int i = 0; i < zcrHistogram.Count; i++)
{
if ((zcrHistogram[i] == 0) || (energyHistogram[i] == 0) || (zcrHistogram[i] > zcrAvg && energyHistogram[i] < energyAvg))
{
//no speech
//check consecutive windows to find the end of this space
for (int j = i + 1; j < zcrHistogram.Count; j++)
{
if (!((zcrHistogram[j] == 0) || (energyHistogram[j] == 0) || (zcrHistogram[j] > zcrAvg && energyHistogram[j] < energyAvg)))
{
spaces.Add(new Space(i * 1000, j * 1000));
i = j;
break;
}
}
}
}
return spaces;
}
/// <summary>
/// This function is to close the video control, it is called by the main control
/// </summary>
private void CloseMediaControlViewModel()
{
_waveform = null;
_mediaVideo.Path = null;
_mediaVideo.Stop();
_mediaVideo.Close();
_mediaVideo.CurrentState = LiveDescribeVideoStates.VideoNotLoaded;
}
private void StripAudioAnContinueLoadingProject(Project project)
{
var worker = new BackgroundWorker { WorkerReportsProgress = true, };
Waveform waveform = null;
//Strip the audio from the given project video
worker.DoWork += (sender, args) =>
{
Log.Info("Beginning to strip audio");
var audioOperator = new AudioUtility(project);
audioOperator.StripAudio(worker);
var waveFormData = audioOperator.ReadWavData(worker);
var audioHeader = audioOperator.Header;
waveform = new Waveform(audioHeader, waveFormData);
Log.Info("Audio stripped");
};
worker.RunWorkerCompleted += (sender, args) =>
{
project.Waveform = waveform;
if (Settings.Default.AutoGenerateSpaces)
{
List<Space> spaceData = AudioAnalyzer.FindSpaces(waveform);
OnSpacesAudioAnalysisCompleted(project, spaceData);
Log.Info("Spaces found");
}
else
Log.Info("Spaces not auto-generated");
FileWriter.WriteWaveFormHeader(project, waveform.Header);
FileWriter.WriteWaveFormFile(project, waveform.Data);
ContinueLoadingProject(project);
};
worker.ProgressChanged += (sender, args) => _loadingViewModel.SetProgress("Importing Video",
args.ProgressPercentage);
_loadingViewModel.SetProgress("Importing Video", 0);
_loadingViewModel.Visible = true;
worker.RunWorkerAsync();
}
