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Misc audio fixes (#1348)

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Changes:

    Implement software surround downmixing (fix #796).
    Fix a crash when no audio renderer were created when stopping emulation.

NOTE: This PR also disable support of 5.1 surround on the OpenAL backend as we cannot detect if the hardware directly support it. (the downmixing applied by OpenAL on Windows is terribly slow)
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Mary 2020-08-18 21:03:55 +02:00 • committed by GitHub
parent a389dd59bd
commit 5b26e4ef94
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11 changed files with 302 additions and 30 deletions
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Ryujinx.Audio/Downmixing.cs Normal file
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using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
namespace Ryujinx.Audio
{
public static class Downmixing
{
[StructLayout(LayoutKind.Sequential, Pack = 1)]
private struct Channel51FormatPCM16
{
public short FrontLeft;
public short FrontRight;
public short FrontCenter;
public short LowFrequency;
public short BackLeft;
public short BackRight;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
private struct ChannelStereoFormatPCM16
{
public short Left;
public short Right;
}
private const int Q15Bits = 16;
private const int RawQ15One = 1 << Q15Bits;
private const int RawQ15HalfOne = (int)(0.5f * RawQ15One);
private const int Minus3dBInQ15 = (int)(0.707f * RawQ15One);
private const int Minus6dBInQ15 = (int)(0.501f * RawQ15One);
private const int Minus12dBInQ15 = (int)(0.251f * RawQ15One);
private static int[] DefaultSurroundToStereoCoefficients = new int[4]
{
RawQ15One,
Minus3dBInQ15,
Minus12dBInQ15,
Minus3dBInQ15,
};
private static int[] DefaultStereoToMonoCoefficients = new int[2]
{
Minus6dBInQ15,
Minus6dBInQ15,
};
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ReadOnlySpan<Channel51FormatPCM16> GetSurroundBuffer(ReadOnlySpan<short> data)
{
return MemoryMarshal.Cast<short, Channel51FormatPCM16>(data);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ReadOnlySpan<ChannelStereoFormatPCM16> GetStereoBuffer(ReadOnlySpan<short> data)
{
return MemoryMarshal.Cast<short, ChannelStereoFormatPCM16>(data);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static short DownMixStereoToMono(ReadOnlySpan<int> coefficients, short left, short right)
{
return (short)((left * coefficients[0] + right * coefficients[1]) >> Q15Bits);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static short DownMixSurroundToStereo(ReadOnlySpan<int> coefficients, short back, short lfe, short center, short front)
{
return (short)((coefficients[3] * back + coefficients[2] * lfe + coefficients[1] * center + coefficients[0] * front + RawQ15HalfOne) >> Q15Bits);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static short[] DownMixSurroundToStereo(ReadOnlySpan<int> coefficients, ReadOnlySpan<short> data)
{
const int SurroundChannelCount = 6;
const int StereoChannelCount = 2;
int samplePerChannelCount = data.Length / SurroundChannelCount;
short[] downmixedBuffer = new short[samplePerChannelCount * StereoChannelCount];
ReadOnlySpan<Channel51FormatPCM16> channels = GetSurroundBuffer(data);
for (int i = 0; i < samplePerChannelCount; i++)
{
Channel51FormatPCM16 channel = channels[i];
downmixedBuffer[i * 2] = DownMixSurroundToStereo(coefficients, channel.BackLeft, channel.LowFrequency, channel.FrontCenter, channel.FrontLeft);
downmixedBuffer[i * 2 + 1] = DownMixSurroundToStereo(coefficients, channel.BackRight, channel.LowFrequency, channel.FrontCenter, channel.FrontRight);
}
return downmixedBuffer;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static short[] DownMixStereoToMono(ReadOnlySpan<int> coefficients, ReadOnlySpan<short> data)
{
const int StereoChannelCount = 2;
const int MonoChannelCount = 1;
int samplePerChannelCount = data.Length / StereoChannelCount;
short[] downmixedBuffer = new short[samplePerChannelCount * MonoChannelCount];
ReadOnlySpan<ChannelStereoFormatPCM16> channels = GetStereoBuffer(data);
for (int i = 0; i < samplePerChannelCount; i++)
{
ChannelStereoFormatPCM16 channel = channels[i];
downmixedBuffer[i] = DownMixStereoToMono(coefficients, channel.Left, channel.Right);
}
return downmixedBuffer;
}
public static short[] DownMixStereoToMono(ReadOnlySpan<short> data)
{
return DownMixStereoToMono(DefaultStereoToMonoCoefficients, data);
}
public static short[] DownMixSurroundToStereo(ReadOnlySpan<short> data)
{
return DownMixSurroundToStereo(DefaultSurroundToStereoCoefficients, data);
}
}
}