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This is the first commit of a series of reformat around the codebase as discussed internally some weeks ago. This project being one that isn't touched that much, it shouldn't cause conflict with any opened PRs.
125 lines
4.7 KiB
C#
125 lines
4.7 KiB
C#
using System;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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namespace Ryujinx.Audio.Backends.CompatLayer
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{
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public static class Downmixing
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{
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[StructLayout(LayoutKind.Sequential, Pack = 1)]
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private struct Channel51FormatPCM16
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{
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public short FrontLeft;
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public short FrontRight;
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public short FrontCenter;
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public short LowFrequency;
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public short BackLeft;
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public short BackRight;
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}
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[StructLayout(LayoutKind.Sequential, Pack = 1)]
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private struct ChannelStereoFormatPCM16
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{
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public short Left;
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public short Right;
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}
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private const int Q15Bits = 16;
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private const int RawQ15One = 1 << Q15Bits;
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private const int RawQ15HalfOne = (int)(0.5f * RawQ15One);
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private const int Minus3dBInQ15 = (int)(0.707f * RawQ15One);
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private const int Minus6dBInQ15 = (int)(0.501f * RawQ15One);
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private const int Minus12dBInQ15 = (int)(0.251f * RawQ15One);
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private static readonly int[] DefaultSurroundToStereoCoefficients = new int[4]
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{
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RawQ15One,
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Minus3dBInQ15,
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Minus12dBInQ15,
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Minus3dBInQ15
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};
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private static readonly int[] DefaultStereoToMonoCoefficients = new int[2]
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{
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Minus6dBInQ15,
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Minus6dBInQ15
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};
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private const int SurroundChannelCount = 6;
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private const int StereoChannelCount = 2;
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private const int MonoChannelCount = 1;
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static ReadOnlySpan<Channel51FormatPCM16> GetSurroundBuffer(ReadOnlySpan<short> data)
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{
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return MemoryMarshal.Cast<short, Channel51FormatPCM16>(data);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static ReadOnlySpan<ChannelStereoFormatPCM16> GetStereoBuffer(ReadOnlySpan<short> data)
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{
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return MemoryMarshal.Cast<short, ChannelStereoFormatPCM16>(data);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static short DownMixStereoToMono(ReadOnlySpan<int> coefficients, short left, short right)
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{
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return (short)((left * coefficients[0] + right * coefficients[1]) >> Q15Bits);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static short DownMixSurroundToStereo(ReadOnlySpan<int> coefficients, short back, short lfe, short center, short front)
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{
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return (short)((coefficients[3] * back + coefficients[2] * lfe + coefficients[1] * center + coefficients[0] * front + RawQ15HalfOne) >> Q15Bits);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static short[] DownMixSurroundToStereo(ReadOnlySpan<int> coefficients, ReadOnlySpan<short> data)
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{
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int samplePerChannelCount = data.Length / SurroundChannelCount;
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short[] downmixedBuffer = new short[samplePerChannelCount * StereoChannelCount];
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ReadOnlySpan<Channel51FormatPCM16> channels = GetSurroundBuffer(data);
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for (int i = 0; i < samplePerChannelCount; i++)
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{
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Channel51FormatPCM16 channel = channels[i];
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downmixedBuffer[i * 2] = DownMixSurroundToStereo(coefficients, channel.BackLeft, channel.LowFrequency, channel.FrontCenter, channel.FrontLeft);
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downmixedBuffer[i * 2 + 1] = DownMixSurroundToStereo(coefficients, channel.BackRight, channel.LowFrequency, channel.FrontCenter, channel.FrontRight);
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}
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return downmixedBuffer;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static short[] DownMixStereoToMono(ReadOnlySpan<int> coefficients, ReadOnlySpan<short> data)
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{
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int samplePerChannelCount = data.Length / StereoChannelCount;
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short[] downmixedBuffer = new short[samplePerChannelCount * MonoChannelCount];
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ReadOnlySpan<ChannelStereoFormatPCM16> channels = GetStereoBuffer(data);
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for (int i = 0; i < samplePerChannelCount; i++)
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{
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ChannelStereoFormatPCM16 channel = channels[i];
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downmixedBuffer[i] = DownMixStereoToMono(coefficients, channel.Left, channel.Right);
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}
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return downmixedBuffer;
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}
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public static short[] DownMixStereoToMono(ReadOnlySpan<short> data)
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{
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return DownMixStereoToMono(DefaultStereoToMonoCoefficients, data);
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}
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public static short[] DownMixSurroundToStereo(ReadOnlySpan<short> data)
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{
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return DownMixSurroundToStereo(DefaultSurroundToStereoCoefficients, data);
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}
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}
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} |