Subset() публичный Метод

public Subset ( int start ) : ISoundObj
start int
Результат ISoundObj
Пример #1
0
        static void Main(string[] args)
        {
            // Find where this executable is launched from
            string[] cargs = Environment.GetCommandLineArgs();
            _thisFolder = Path.GetDirectoryName(cargs[0]);
            if (String.IsNullOrEmpty(_thisFolder))
            {
                _thisFolder = Environment.CurrentDirectory;
            }

            string appData = Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData);
            _impulsesFolder = Path.GetFullPath(Path.Combine(appData, "InguzEQ" + slash + "Impulses" + slash));

            string[] inFiles = new string[4];
            string inL = "";
            string inR = "";
            if (!DisplayInfo())
            {
                return;
            }

            bool ok = (args.Length > 0);
            bool longUsage = false;

            for (int j = 0; ok && j < args.Length; j++)
            {
                string arg = args[j];
                switch (args[j].ToUpperInvariant())
                {
                    case "/?":
                    case "-?":
                    case "/H":
                    case "/HELP":
                        ok = false;
                        longUsage = true;
                        break;

                    case "/L":
                    case "/0":
                        inFiles[0] = args[++j];
                        _nInFiles = Math.Max(_nInFiles, 1);
                        break;

                    case "/R":
                    case "/1":
                        inFiles[1] = args[++j];
                        _nInFiles = Math.Max(_nInFiles, 2);
                        break;

                    case "/2":
                        inFiles[2] = args[++j];
                        _nInFiles = Math.Max(_nInFiles, 3);
                        break;
                    case "/3":
                        inFiles[3] = args[++j];
                        _nInFiles = Math.Max(_nInFiles, 4);
                        break;

                    case "/LENGTH":
                        _filterLen = int.Parse(args[++j], CultureInfo.InvariantCulture);
                        if (_filterLen < 16)
                        {
                            throw new Exception("Length is too small.");
                        }
                        break;

                    case "/DBL":
                        _dbl = true;
                        break;

                    case "/PCM":
                        _pcm = true;
                        break;

                    case "/NODRC":
                        _noDRC = true;
                        break;

                    case "/NOSKEW":
                        _noSkew = true;
                        break;

                    case "/NONORM":
                        // No normalization of the impulse response (undocumented)
                        _noNorm = true;
                        break;

                    case "/SPLIT":
                        _split = true;
                        break;

                    case "/COPY":
                        _copy = true;
                        break;

                    case "/GAIN":
                        _gain = double.Parse(args[++j], CultureInfo.InvariantCulture);
                        break;

                    case "/ALL":
                        // Returns negative-time components as part of the impulse response
                        // (experimental, to be used for THD measurement)
                        _returnAll = true;
                        break;

                    case "/POWER":
                        // Raises sweep to power n
                        // (experimental, to be used for THD measurement)
                        _power = int.Parse(args[++j], CultureInfo.InvariantCulture);
                        break;

                    case "/FMIN":
                        // (experimental, i.e. broken)
                        _fmin = int.Parse(args[++j], CultureInfo.InvariantCulture);
                        _fminSpecified = true;
                        break;

                    case "/FMAX":
                        // (experimental, i.e. broken)
                        _fmax = int.Parse(args[++j], CultureInfo.InvariantCulture);
                        _fmaxSpecified = true;
                        break;

                    case "/DIRECT":
                        // Create filtered (direct-sound) filters
                        _doDirectFilters = true;
                        break;

                    case "/NOSUB":
                        // Don't apply subsonic filter to the impulse response
                        _noSubsonicFilter = true;
                        break;

                    case "/NOOVER":
                        // Don't override DRC's settings for filter type and length
                        _noOverrideDRC = true;
                        break;

                    case "/KEEPTEMP":
                        // Undocumented
                        _keepTempFiles = true;
                        break;

                    case "/REFCH":
                        // Override the reference-channel detection
                        _refchannel = int.Parse(args[++j], CultureInfo.InvariantCulture);
                        if (_refchannel<0 || _refchannel > _nInFiles - 1)
                        {
                            throw new Exception(String.Format("RefCh can only be from 0 to {0}.", _nInFiles-1));
                        }
                        break;

                    case "/ENV":
                        // Undocumented.  Save the Hilbert envelope
                        _env = true;
                        break;

                    case "-":
                        // ignore
                        break;

                    default:
                        ok = false;
                        break;
                }
            }
            if (!ok)
            {
                DisplayUsage(longUsage);
            }
            else
            {
                try
                {
                    if (!_noDRC)
                    {
                        if (!File.Exists(GetDRCExe()))
                        {
                            stderr.WriteLine("Denis Sbragion's DRC (http://drc-fir.sourceforge.net/) was not found.");
                            stderr.WriteLine("Only the impulse response will be calculated, not correction filters.");
                            stderr.WriteLine("");
                            _noDRC = true;
                        }
                    }
                    if (!_noDRC)
                    {
                        FileInfo[] drcfiles = new DirectoryInfo(_thisFolder).GetFiles("*.drc");
                        if (drcfiles.Length == 0)
                        {
                            stderr.WriteLine("No .drc files were found in the current folder.");
                            stderr.WriteLine("Only the impulse response will be calculated, not correction filters.");
                            stderr.WriteLine("");
                            _noDRC = true;
                        }
                    }

                    for(int i=0; i<_nInFiles; i++)
                    {
                        string inFile = inFiles[i];
                        if (String.IsNullOrEmpty(inFile))
                        {
                            stderr.WriteLine("Error: The {0} input file was not specified.", FileDescription(i));
                            return;
                        }
                        if (!File.Exists(inFile))
                        {
                            stderr.WriteLine("Error: The {0} input file {1} was not found.", FileDescription(i), inFile);
                            return;
                        }

                        for (int j = 0; j < i; j++)
                        {
                            if (inFile.Equals(inFiles[j]))
                            {
                                stderr.WriteLine("Warning: The same input file ({0}) was specified for both {1} and {2}!", inFile, FileDescription(j), FileDescription(i));
                                //stderr.WriteLine();
                            }
                        }
                    }

                    // Temporary
                    if (_nInFiles != 2)
                    {
                        stderr.WriteLine("Error: Two input files must be specified.");
                        return;
                    }
                    inL = inFiles[0];
                    inR = inFiles[1];
                    // end temporary

                    uint sampleRate;
                    List<SoundObj> impulses;
                    List<ISoundObj> filteredImpulses;
                    List<string> impDirects;
                    List<Complex[]> impulseFFTs;
                    List<double> maxs;

                    SoundObj impulseL;
                    SoundObj impulseR;
                    ISoundObj filteredImpulseL = null;
                    ISoundObj filteredImpulseR = null;

                    string impDirectL = null;
                    string impDirectR = null;

                    Complex[] impulseLFFT;
                    Complex[] impulseRFFT;
                    WaveWriter writer;

                    ISoundObj buff;
                    double g;

                    if (!_keepTempFiles)
                    {
                        _tempFiles.Add("rps.pcm");
                        _tempFiles.Add("rtc.pcm");
                    }

                    // Find the left impulse
                    stderr.WriteLine("Processing left measurement ({0})...", inL);
                    impulseL = Deconvolve(inL, out impulseLFFT, out _peakPosL);
                    sampleRate = impulseL.SampleRate;
                    _sampleRate = sampleRate;
                    double peakM = Math.Round(MathUtil.Metres(_peakPosL, sampleRate), 2);
                    double peakFt = Math.Round(MathUtil.Feet(_peakPosL, sampleRate), 2);
                    stderr.WriteLine("  Impulse peak at sample {0} ({1}m, {2}ft)", _peakPosL, peakM, peakFt);

                    // Write to PCM
                    string impFileL = Path.GetFileNameWithoutExtension(inL) + "_imp" + ".pcm";
                    if (!_keepTempFiles)
                    {
                        _tempFiles.Add(impFileL);
                    }
                    writer = new WaveWriter(impFileL);
                    writer.Input = impulseL;
                    writer.Format = WaveFormat.IEEE_FLOAT;
                    writer.BitsPerSample = 32;
                    writer.SampleRate = _sampleRate;
                    writer.Raw = true;
                    writer.Run();
                    writer.Close();

                    // Write the impulseFFT to disk
                    int L = impulseLFFT.Length;
                    string impTempL = Path.GetFileNameWithoutExtension(inL) + "_imp" + ".dat";
                    _tempFiles.Add(impTempL);
                    writer = new WaveWriter(impTempL);
                    writer.Input = new CallbackSource(2, sampleRate, delegate(long j)
                    {
                        if (j >= L / 2)
                        {
                            return null;
                        }
                        Complex si = impulseLFFT[j]; // +impulseLFFT[L - j - 1];
                        ISample s = new Sample2();
                        s[0] = si.Magnitude;
                        s[1] = si.Phase / Math.PI;
                        return s;
                    });
                    writer.Format = WaveFormat.IEEE_FLOAT;
                    writer.BitsPerSample = 32;
                    writer.SampleRate = _sampleRate;
                    writer.Raw = false;
                    writer.Run();
                    writer.Close();
                    writer = null;

                    impulseLFFT = null;
                    GC.Collect();

                    if (_doDirectFilters)
                    {
                        // Sliding low-pass filter over the impulse
                        stderr.WriteLine("  Filtering...");
                        filteredImpulseL = SlidingLowPass(impulseL, _peakPosL);

                        // Write PCM for the filtered impulse
                        impDirectL = Path.GetFileNameWithoutExtension(inL) + "_impfilt" + ".pcm";
                        if (!_keepTempFiles)
                        {
                            _tempFiles.Add(impDirectL);
                        }
                        writer = new WaveWriter(impDirectL);
                        writer.Input = filteredImpulseL;
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.SampleRate = _sampleRate;
                        writer.BitsPerSample = 32;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        writer = null;
                        filteredImpulseL.Reset();
                    }

                    GC.Collect();
                    stderr.WriteLine("  Deconvolution: left impulse done.");
                    stderr.WriteLine();

                    // Find the right impulse
                    stderr.WriteLine("Processing right measurement ({0})...", inR);
                    impulseR = Deconvolve(inR, out impulseRFFT, out _peakPosR);
                    peakM = Math.Round(MathUtil.Metres(_peakPosR, sampleRate), 2);
                    peakFt = Math.Round(MathUtil.Feet(_peakPosR, sampleRate), 2);
                    stderr.WriteLine("  Impulse peak at sample {0} ({1}m, {2}ft)", _peakPosR, peakM, peakFt);

                    // Write to PCM
                    string impFileR = Path.GetFileNameWithoutExtension(inR) + "_imp" + ".pcm";
                    if (!_keepTempFiles)
                    {
                        _tempFiles.Add(impFileR);
                    }
                    writer = new WaveWriter(impFileR);
                    writer.Input = impulseR;
                    writer.Format = WaveFormat.IEEE_FLOAT;
                    writer.BitsPerSample = 32;
                    writer.SampleRate = _sampleRate;
                    writer.Raw = true;
                    writer.Run();
                    writer.Close();

                    // Write the impulseFFT magnitude to disk
                    L = impulseRFFT.Length;
                    string impTempR = Path.GetFileNameWithoutExtension(inR) + "_imp" + ".dat";
                    _tempFiles.Add(impTempR);
                    writer = new WaveWriter(impTempR);
                    writer.Input = new CallbackSource(2, impulseR.SampleRate, delegate(long j)
                    {
                        if (j >= L / 2)
                        {
                            return null;
                        }
                        Complex si = impulseRFFT[j]; // +impulseRFFT[L - j - 1];
                        ISample s = new Sample2();
                        s[0] = si.Magnitude;
                        s[1] = si.Phase / Math.PI;
                        return s;
                    });
                    writer.Format = WaveFormat.IEEE_FLOAT;
                    writer.BitsPerSample = 32;
                    writer.SampleRate = _sampleRate;
                    writer.Raw = false;
                    writer.Run();
                    writer.Close();
                    writer = null;

                    impulseRFFT = null;
                    GC.Collect();

                    if (_doDirectFilters)
                    {
                        // Sliding low-pass filter over the impulse
                        stderr.WriteLine("  Filtering...");
                        filteredImpulseR = SlidingLowPass(impulseR, _peakPosR);

                        // Write PCM for the filtered impulse
                        impDirectR = Path.GetFileNameWithoutExtension(inR) + "_impfilt" + ".pcm";
                        if (!_keepTempFiles)
                        {
                            _tempFiles.Add(impDirectR);
                        }
                        writer = new WaveWriter(impDirectR);
                        writer.Input = filteredImpulseR;
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.BitsPerSample = 32;
                        writer.SampleRate = _sampleRate;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        writer = null;
                        filteredImpulseR.Reset();
                    }

                    GC.Collect();

                    stderr.WriteLine("  Deconvolution: right impulse done.");
                    stderr.WriteLine();

                    // Join the left and right impulse files (truncated at 65536) into a WAV
                    // and normalize loudness for each channel
                    stderr.WriteLine("Splicing and normalizing (1)");
                    ChannelSplicer longstereoImpulse = new ChannelSplicer();

                    // (Don't normalize each channel's volume separately if _returnAll, it's just too expensive)
                    if (_returnAll)
                    {
                        buff = impulseL;
                    }
                    else
                    {
                        buff = new SoundBuffer(new SampleBuffer(impulseL).Subset(0, 131071));
                        g = Loudness.WeightedVolume(buff);
                        (buff as SoundBuffer).ApplyGain(1 / g);
                    }
                    longstereoImpulse.Add(buff);

                    if (_returnAll)
                    {
                        buff = impulseR;
                    }
                    else
                    {
                        buff = new SoundBuffer(new SampleBuffer(impulseR).Subset(0, 131071));
                        g = Loudness.WeightedVolume(buff);
                        (buff as SoundBuffer).ApplyGain(1 / g);
                    }
                    longstereoImpulse.Add(buff);

                    ISoundObj stereoImpulse = longstereoImpulse;

                    _impulseFiles.Add("Impulse_Response_Measured.wav: stereo impulse response from measurements");
                    writer = new WaveWriter("Impulse_Response_Measured.wav");
                    writer.Input = longstereoImpulse;
                    writer.Format = WaveFormat.IEEE_FLOAT;
                    writer.BitsPerSample = 32;
                    writer.SampleRate = _sampleRate;
                    writer.Normalization = -1;
                    writer.Raw = false;
                    writer.Run();
                    writer.Close();
                    writer = null;

                    if (_env)
                    {
                        // Also save the Hilbert envelope
                        HilbertEnvelope env = new HilbertEnvelope(8191);
                        env.Input = longstereoImpulse;
                        _impulseFiles.Add("Impulse_Response_Envelope.wav: Hilbert envelope of the impulse response");
                        writer = new WaveWriter("Impulse_Response_Envelope.wav");
                        writer.Input = env;
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.BitsPerSample = 32;
                        writer.SampleRate = _sampleRate;
                        writer.Normalization = -1;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        writer = null;
                    }

                    if (_dbl)
                    {
                        // Create DBL files for Acourate
                        _impulseFiles.Add("PulseL.dbl: impulse response, raw data (64-bit float), left channel ");
                        _impulseFiles.Add("PulseR.dbl: impulse response, raw data (64-bit float), right channel");
                        _impulseFiles.Add("  (use skew=" + (_peakPosL - _peakPosR) + " for time alignment)");
                        WriteImpulseDBL(stereoImpulse, "PulseL.dbl", "PulseR.dbl");
                    }

                    if (_pcm)
                    {
                        // Create PCM files for Octave (etc)
                        _impulseFiles.Add("LUncorrected.pcm: impulse response, raw data (32-bit float), left channel");
                        _impulseFiles.Add("RUncorrected.pcm: impulse response, raw data (32-bit float), right channel");
                        WriteImpulsePCM(stereoImpulse, "LUncorrected.pcm", "RUncorrected.pcm");
                    }

                    stereoImpulse = null;
                    longstereoImpulse = null;
                    buff = null;
                    GC.Collect();

                    if (_doDirectFilters)
                    {
                        // Same for the filtered impulse response
                        stderr.WriteLine("Splicing and normalizing (2)");
                        ChannelSplicer longstereoImpulseF = new ChannelSplicer();

                        buff = new SoundBuffer(new SampleBuffer(filteredImpulseL).Subset(0, 131071));
                        double gL = Loudness.WeightedVolume(buff);
                        (buff as SoundBuffer).ApplyGain(1 / gL);
                        longstereoImpulseF.Add(buff);
                        FilterProfile lfgDirectL = new FilterProfile(buff, 0.5);

                        buff = new SoundBuffer(new SampleBuffer(filteredImpulseR).Subset(0, 131071));
                        double gR = Loudness.WeightedVolume(buff);
                        (buff as SoundBuffer).ApplyGain(1 / gR);
                        longstereoImpulseF.Add(buff);
                        FilterProfile lfgDirectR = new FilterProfile(buff, 0.5);

                        _impulseFiles.Add("Impulse_Response_Filtered.wav: approximation to direct-sound impulse response");
                        writer = new WaveWriter("Impulse_Response_Filtered.wav");
                        writer.Input = longstereoImpulseF;
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.BitsPerSample = 32;
                        writer.SampleRate = _sampleRate;
                        writer.Normalization = -1;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        double gg = writer.Gain;
                        writer = null;
                        longstereoImpulseF = null;

                        ChannelSplicer longstereoImpulseD = new ChannelSplicer();

                        Mixer diffuse = new Mixer();
                        diffuse.Add(impulseL, 1.0);
                        diffuse.Add(filteredImpulseL, -1.0);
                        buff = new SoundBuffer(new SampleBuffer(diffuse).Subset(0, 131071));
                        (buff as SoundBuffer).ApplyGain(1 / gL);
                        longstereoImpulseD.Add(buff);
                        FilterProfile lfgDiffuseL = new FilterProfile(buff, 0.5);

                        diffuse = new Mixer();
                        diffuse.Add(impulseR, 1.0);
                        diffuse.Add(filteredImpulseR, -1.0);
                        buff = new SoundBuffer(new SampleBuffer(diffuse).Subset(0, 131071));
                        (buff as SoundBuffer).ApplyGain(1 / gR);
                        longstereoImpulseD.Add(buff);
                        FilterProfile lfgDiffuseR = new FilterProfile(buff, 0.5);

                        _impulseFiles.Add("Impulse_Response_Diffuse.wav: approximation to diffuse-field remnant");
                        writer = new WaveWriter("Impulse_Response_Diffuse.wav");
                        writer.Input = longstereoImpulseD;
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.BitsPerSample = 32;
                        writer.SampleRate = _sampleRate;
                        writer.Gain = gg;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        writer = null;

                        // Filter the diffuse-field curve against double the diffuse-field curve
                        FilterImpulse fiDiffuse = new FilterImpulse(8192, HRTF.diffuseDiff0() * 2, FilterInterpolation.COSINE, sampleRate);
                        FastConvolver co = new FastConvolver(longstereoImpulseD, fiDiffuse);
                        SoundBuffer buffd = new SoundBuffer(co);
                        _impulseFiles.Add("Impulse_Response_Diffuse_Comp.wav: filtered diffuse-field remnant");
                        writer = new WaveWriter("Impulse_Response_Diffuse_Comp.wav");
                        writer.Input = buffd.Subset(4096);
                        writer.Format = WaveFormat.IEEE_FLOAT;
                        writer.BitsPerSample = 32;
                        writer.SampleRate = _sampleRate;
                        writer.Gain = gg;
                        writer.Raw = false;
                        writer.Run();
                        writer.Close();
                        writer = null;

                        longstereoImpulseD = null;

                        bool any = false;
                        string jsonFile = "Diff.json";
                        FileStream fs = new FileStream(jsonFile, FileMode.Create);
                        StreamWriter sw = new StreamWriter(fs);
                        sw.WriteLine("{");
                        FilterProfile lfgDiffL = lfgDirectL - lfgDiffuseL;
                        if (lfgDiffL != null)
                        {
                            if (any) sw.WriteLine(",");
                            any = true;
                            sw.Write(lfgDiffL.ToJSONString("DiffL", "Diffuse field relative to direct, left channel"));
                        }
                        FilterProfile lfgDiffR = lfgDirectR - lfgDiffuseR;
                        if (lfgDiffR != null)
                        {
                            if (any) sw.WriteLine(",");
                            any = true;
                            sw.Write(lfgDiffR.ToJSONString("DiffR", "Diffuse field relative to direct, right channel"));
                        }
                        sw.WriteLine("}");
                        sw.Close();
                        fs.Close();
                    }
                    buff = null;
                    GC.Collect();

                    System.Console.Error.WriteLine();

                    if (!_noDRC)
                    {
                        // Analyze the freq response
                        // and create targets
                        // target_full.txt and target_half.txt
                        stderr.WriteLine("Analyzing response curves.");
                        Prep(impTempL, impTempR, "Impulse_Response_Measured.wav", "NoCorrection");

                        // Call DRC to create the filters
                        // then splice the DRC left & right output files together
                        stderr.WriteLine("Preparing for DRC.");
                        if (DoDRC(impFileL, impFileR, impDirectL, impDirectR, _peakPosL, _peakPosR, "Impulse_Response_Measured.wav", "Impulse_Response_Filtered.wav"))
                        {
                            stderr.WriteLine("Success!");
                        }
                    }

                    // Report names of the impulse files created
                    if (_impulseFiles.Count == 0)
                    {
                        System.Console.Error.WriteLine("No impulse response files were created.");
                    }
                    if (_impulseFiles.Count > 0)
                    {
                        System.Console.Error.WriteLine("Impulse response files were created:");
                        foreach (string f in _impulseFiles)
                        {
                            string s = "  " + f;
                            System.Console.Error.WriteLine(s);
                        }
                    }

                    // Report names of the filter files created
                    if (_filterFiles.Count == 0 && !_noDRC)
                    {
                        System.Console.Error.WriteLine("No correction filter files were created.");
                    }
                    if (_filterFiles.Count > 0)
                    {
                        System.Console.Error.WriteLine("Correction filter files were created:");
                        foreach (string f in _filterFiles)
                        {
                            string s = "  " + f;
                            if (_copy)
                            {
                                try
                                {
                                    File.Copy(f, Path.Combine(_impulsesFolder, f), true);
                                    s += " (copied)";
                                }
                                catch (Exception e)
                                {
                                    s += " (not copied: " + e.Message + ")";
                                }
                            }
                            System.Console.Error.WriteLine(s);
                        }
                    }
                    if (_peakPosL == _peakPosR)
                    {
                        System.Console.Error.WriteLine();
                        System.Console.Error.WriteLine("Zero time difference between channels.  Are you sure the recordings are correct?");
                    }
                }
                catch (Exception e)
                {
                    stderr.WriteLine();
                    stderr.WriteLine(e.Message);
                    stderr.WriteLine(e.StackTrace);
                }
                finally
                {
                    foreach (string tempFile in _tempFiles)
                    {
                        try
                        {
                            File.Delete(tempFile);
                        }
                        catch (Exception) { /* ignore */ }
                    }
                }
            }
            stderr.Flush();
        }
Пример #2
0
        static SoundObj GetMainImpulse(out string actualPath)
        {
            DateTime dtStart = DateTime.Now;
            if (_impulsePath == "") _impulsePath = null;
            if (_impulsePath == "-") _impulsePath = null;
            if (_matrixFilter == "") _matrixFilter = null;
            if (_matrixFilter == "-") _matrixFilter = null;
            if (_bformatFilter == "") _bformatFilter = null;
            if (_bformatFilter == "-") _bformatFilter = null;
            Trace.WriteLine("Impulse {0}, matrix {1}", CleanPath(_dataFolder, _impulsePath), CleanPath(_dataFolder, _matrixFilter));

            // note: we window the room correction impulse if it's too long
            WaveReader impulseReader = null;
            SoundObj impulseObj = null;
            actualPath = null;

            if (!String.IsNullOrEmpty(_impulsePath))
            {
                impulseReader = GetAppropriateImpulseReader(_impulsePath, out actualPath);
            }
            if (impulseReader != null)
            {
                if (impulseReader.Iterations > _maxImpulseLength)
                {
                    // This impulse is too long.
                    // Trim it to length.
                    int hwid = _maxImpulseLength / 2;
                    int qwid = _maxImpulseLength / 4;
                    SoundBuffer buff = new SoundBuffer(impulseReader);
                    buff.ReadAll();
                    int center = buff.MaxPos();
                    BlackmanHarris wind;
                    int startpos;
                    if (center < hwid)
                    {
                        wind = new BlackmanHarris(center, qwid, qwid);
                        startpos = 0;
                    }
                    else
                    {
                        wind = new BlackmanHarris(hwid, qwid, qwid);
                        startpos = center - hwid;
                    }
                    //                        int startpos = center < hwid ? 0 : (center - hwid);
                    wind.Input = buff.Subset(startpos, _maxImpulseLength);
                    impulseObj = wind;
                }
                else
                {
                    impulseObj = impulseReader;
                }
            }

            if (_debug)
            {
                TimeSpan ts = DateTime.Now.Subtract(dtStart);
                Trace.WriteLine("GetMainImpulse " + ts.TotalMilliseconds);
            }
            return impulseObj;
        }