// FEATURES
/// =======================================================================================================
public static void WAV_LP_FILTER(string path, string cut_off_hz, string start_ms, string end_ms)
{
byte[] alldata = File.ReadAllBytes(path);
double cutoff = Convert.ToDouble(cut_off_hz);
int startofdata = GetStartOfDataIndex(alldata);
WAVFormat fmt = ReadFormat(alldata);
uint total = (uint)(alldata.Length - startofdata) / (fmt.NumberOfChannels * fmt.ByteDepth);
uint start = 0;
try { start = ConvertMsToNumberOfBytes(Convert.ToUInt32(start_ms), fmt) / (fmt.NumberOfChannels * fmt.ByteDepth); } catch { }
uint end = total;
try { end = ConvertMsToNumberOfBytes(Convert.ToUInt32(end_ms), fmt) / (fmt.NumberOfChannels * fmt.ByteDepth); } catch { }
double[] left;
double[] right;
GetDoubleArrayFromBytes(alldata, out left, out right);
double[] leftsection = new double[end - start];
double[] rightsection = new double[end - start];
Array.Copy(left, start, leftsection, 0, leftsection.Length);
Array.Copy(right, start, rightsection, 0, rightsection.Length);
LPFilter.Butterworth(ref leftsection, fmt.SampleRate, cutoff);
LPFilter.Butterworth(ref rightsection, fmt.SampleRate, cutoff);
Array.Copy(leftsection, 0, left, start, leftsection.Length);
Array.Copy(rightsection, 0, right, start, rightsection.Length);
double[,] allsamples = new double[fmt.NumberOfChannels, left.Length];
for (int i = 0; i < fmt.NumberOfChannels; i++)
{
for (int j = 0; j < left.Length; j++)
{
if (i == 0)
{
allsamples[i, j] = left[j];
}
else
{
allsamples[i, j] = right[j];
}
}
}
byte[] data = GetBytesFromDoubleArray(allsamples, fmt);
Array.Copy(data, 0, alldata, startofdata, data.Length);
File.WriteAllBytes(DISK.AutoIncrementFilename(path), alldata);
}
public LPFilterVM()
{
Switch = new LpFilterCmd();
_lpFilter = new LPFilter();
}