using AliFsmnVadSharp.Model;
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using KaldiNativeFbankSharp;
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namespace AliFsmnVadSharp
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{
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internal class WavFrontend : IDisposable
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{
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private bool _disposed;
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private FrontendConfEntity _frontendConfEntity;
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OnlineFbank _onlineFbank;
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private CmvnEntity _cmvnEntity;
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private static int _fbank_beg_idx = 0;
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public WavFrontend(string mvnFilePath, FrontendConfEntity frontendConfEntity)
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{
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_frontendConfEntity = frontendConfEntity;
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_fbank_beg_idx = 0;
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_onlineFbank = new OnlineFbank(
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dither: _frontendConfEntity.dither,
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snip_edges: true,
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sample_rate: _frontendConfEntity.fs,
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num_bins: _frontendConfEntity.n_mels
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);
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_cmvnEntity = LoadCmvn(mvnFilePath);
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}
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public float[] GetFbank(float[] samples)
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{
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float sample_rate = _frontendConfEntity.fs;
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samples = samples.Select((float x) => x * 32768f).ToArray();
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float[] fbanks = _onlineFbank.GetFbank(samples);
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return fbanks;
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}
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public float[] LfrCmvn(float[] fbanks)
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{
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float[] features = fbanks;
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if (_frontendConfEntity.lfr_m != 1 || _frontendConfEntity.lfr_n != 1)
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{
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features = ApplyLfr(fbanks, _frontendConfEntity.lfr_m, _frontendConfEntity.lfr_n);
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}
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if (_cmvnEntity != null)
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{
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features = ApplyCmvn(features);
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}
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return features;
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}
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private float[] ApplyCmvn(float[] inputs)
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{
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var arr_neg_mean = _cmvnEntity.Means;
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float[] neg_mean = arr_neg_mean.Select(x => (float)Convert.ToDouble(x)).ToArray();
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var arr_inv_stddev = _cmvnEntity.Vars;
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float[] inv_stddev = arr_inv_stddev.Select(x => (float)Convert.ToDouble(x)).ToArray();
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int dim = neg_mean.Length;
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int num_frames = inputs.Length / dim;
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for (int i = 0; i < num_frames; i++)
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{
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for (int k = 0; k != dim; ++k)
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{
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inputs[dim * i + k] = (inputs[dim * i + k] + neg_mean[k]) * inv_stddev[k];
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}
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}
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return inputs;
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}
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public float[] ApplyLfr(float[] inputs, int lfr_m, int lfr_n)
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{
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int t = inputs.Length / 80;
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int t_lfr = (int)Math.Floor((double)(t / lfr_n));
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float[] input_0 = new float[80];
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Array.Copy(inputs, 0, input_0, 0, 80);
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int tile_x = (lfr_m - 1) / 2;
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t = t + tile_x;
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float[] inputs_temp = new float[t * 80];
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for (int i = 0; i < tile_x; i++)
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{
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Array.Copy(input_0, 0, inputs_temp, tile_x * 80, 80);
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}
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Array.Copy(inputs, 0, inputs_temp, tile_x * 80, inputs.Length);
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inputs = inputs_temp;
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float[] LFR_outputs = new float[t_lfr * lfr_m * 80];
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for (int i = 0; i < t_lfr; i++)
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{
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if (lfr_m <= t - i * lfr_n)
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{
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Array.Copy(inputs, i * lfr_n * 80, LFR_outputs, i* lfr_m * 80, lfr_m * 80);
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}
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else
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{
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// process last LFR frame
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int num_padding = lfr_m - (t - i * lfr_n);
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float[] frame = new float[lfr_m * 80];
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Array.Copy(inputs, i * lfr_n * 80, frame, 0, (t - i * lfr_n) * 80);
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for (int j = 0; j < num_padding; j++)
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{
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Array.Copy(inputs, (t - 1) * 80, frame, (lfr_m - num_padding + j) * 80, 80);
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}
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Array.Copy(frame, 0, LFR_outputs, i * lfr_m * 80, frame.Length);
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}
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}
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return LFR_outputs;
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}
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private CmvnEntity LoadCmvn(string mvnFilePath)
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{
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List<float> means_list = new List<float>();
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List<float> vars_list = new List<float>();
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FileStreamOptions options = new FileStreamOptions();
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options.Access = FileAccess.Read;
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options.Mode = FileMode.Open;
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StreamReader srtReader = new StreamReader(mvnFilePath, options);
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int i = 0;
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while (!srtReader.EndOfStream)
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{
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string? strLine = srtReader.ReadLine();
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if (!string.IsNullOrEmpty(strLine))
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{
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if (strLine.StartsWith("<AddShift>"))
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{
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i=1;
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continue;
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}
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if (strLine.StartsWith("<Rescale>"))
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{
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i = 2;
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continue;
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}
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if (strLine.StartsWith("<LearnRateCoef>") && i==1)
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{
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string[] add_shift_line = strLine.Substring(strLine.IndexOf("[") + 1, strLine.LastIndexOf("]") - strLine.IndexOf("[") - 1).Split(" ");
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means_list = add_shift_line.Where(x => !string.IsNullOrEmpty(x)).Select(x => float.Parse(x.Trim())).ToList();
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continue;
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}
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if (strLine.StartsWith("<LearnRateCoef>") && i==2)
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{
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string[] rescale_line = strLine.Substring(strLine.IndexOf("[") + 1, strLine.LastIndexOf("]") - strLine.IndexOf("[") - 1).Split(" ");
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vars_list = rescale_line.Where(x => !string.IsNullOrEmpty(x)).Select(x => float.Parse(x.Trim())).ToList();
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continue;
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}
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}
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}
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CmvnEntity cmvnEntity = new CmvnEntity();
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cmvnEntity.Means = means_list;
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cmvnEntity.Vars = vars_list;
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return cmvnEntity;
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}
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protected virtual void Dispose(bool disposing)
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{
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if (!_disposed)
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{
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if (disposing)
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{
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if (_onlineFbank != null)
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{
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_onlineFbank.Dispose();
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}
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}
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_disposed = true;
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}
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}
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public void Dispose()
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{
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Dispose(disposing: true);
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GC.SuppressFinalize(this);
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}
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~WavFrontend()
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{
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Dispose(_disposed);
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}
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}
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}
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