namespace NSpeex
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{
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using System;
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internal class Stereo
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{
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private float balance = 1f;
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private float e_ratio = 0.5f;
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private static readonly float[] e_ratio_quant = new float[] { 0.25f, 0.315f, 0.397f, 0.5f };
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private float smooth_left = 1f;
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private float smooth_right = 1f;
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private const int SPEEX_INBAND_STEREO = 9;
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public void Decode(float[] data, int frameSize)
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{
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int num;
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float num2 = 0f;
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for (num = frameSize - 1; num >= 0; num--)
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{
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num2 += data[num] * data[num];
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}
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float num5 = num2 / this.e_ratio;
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float num3 = (num5 * this.balance) / (1f + this.balance);
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float num4 = num5 - num3;
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num3 = (float)Math.Sqrt((double)(num3 / (num2 + 0.01f)));
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num4 = (float)Math.Sqrt((double)(num4 / (num2 + 0.01f)));
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for (num = frameSize - 1; num >= 0; num--)
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{
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float num6 = data[num];
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this.smooth_left = (0.98f * this.smooth_left) + (0.02f * num3);
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this.smooth_right = (0.98f * this.smooth_right) + (0.02f * num4);
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data[2 * num] = this.smooth_left * num6;
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data[(2 * num) + 1] = this.smooth_right * num6;
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}
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}
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public static void Encode(Bits bits, float[] data, int frameSize)
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{
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float num3 = 0f;
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float num4 = 0f;
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float num5 = 0f;
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for (int i = 0; i < frameSize; i++)
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{
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num3 += data[2 * i] * data[2 * i];
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num4 += data[(2 * i) + 1] * data[(2 * i) + 1];
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data[i] = 0.5f * (data[2 * i] + data[(2 * i) + 1]);
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num5 += data[i] * data[i];
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}
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float num6 = (num3 + 1f) / (num4 + 1f);
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float num7 = num5 / ((1f + num3) + num4);
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bits.Pack(14, 5);
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bits.Pack(9, 4);
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num6 = (float)(4.0 * Math.Log((double)num6));
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if (num6 > 0f)
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{
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bits.Pack(0, 1);
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}
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else
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{
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bits.Pack(1, 1);
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}
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num6 = (float)Math.Floor((double)(0.5f + Math.Abs(num6)));
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if (num6 > 30f)
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{
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num6 = 31f;
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}
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bits.Pack((int)num6, 5);
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int num2 = VQ.Index(num7, e_ratio_quant, 4);
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bits.Pack(num2, 2);
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}
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public void Init(Bits bits)
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{
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float num = 1f;
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if (bits.Unpack(1) != 0)
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{
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num = -1f;
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}
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int index = bits.Unpack(5);
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this.balance = (float)Math.Exp((num * 0.25) * index);
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index = bits.Unpack(2);
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this.e_ratio = e_ratio_quant[index];
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}
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}
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}
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