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Audren: Implement polyphase upsampler (#4256)

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* Audren: Implement polyphase upsampler

* prefer shifting to modulo

* prefer MathF

* fix nits

* rm ResampleForUpsampler

* oop

* Array20

* nits
This commit is contained in:
merry 2023-01-15 04:20:49 +00:00 committed by GitHub
parent 8071c8c8c0
commit 41bba5310a
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5 changed files with 201 additions and 52 deletions
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12
Ryujinx.Audio/Renderer/Dsp/Command/UpsampleCommand.cs
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@ -40,6 +40,12 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
info.InputBufferIndices[i] = (ushort)(bufferOffset + inputBufferOffset[i]);
}
if (info.BufferStates?.Length != (int)inputCount)
{
// Keep state if possible.
info.BufferStates = new UpsamplerBufferState[(int)inputCount];
}
UpsamplerInfo = info;
}
@ -50,8 +56,6 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
public void Process(CommandList context)
{
float ratio = (float)InputSampleRate / Constants.TargetSampleRate;
uint bufferCount = Math.Min(BufferCount, UpsamplerInfo.SourceSampleCount);
for (int i = 0; i < bufferCount; i++)
@ -59,9 +63,7 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
Span<float> inputBuffer = context.GetBuffer(UpsamplerInfo.InputBufferIndices[i]);
Span<float> outputBuffer = GetBuffer(UpsamplerInfo.InputBufferIndices[i], (int)UpsamplerInfo.SampleCount);
float fraction = 0.0f;
ResamplerHelper.ResampleForUpsampler(outputBuffer, inputBuffer, ratio, ref fraction, (int)(InputSampleCount / ratio));
UpsamplerHelper.Upsample(outputBuffer, inputBuffer, (int)UpsamplerInfo.SampleCount, (int)InputSampleCount, ref UpsamplerInfo.BufferStates[i]);
}
}
}

47
Ryujinx.Audio/Renderer/Dsp/ResamplerHelper.cs
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@ -579,52 +579,5 @@ namespace Ryujinx.Audio.Renderer.Dsp
fraction -= (int)fraction;
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void ResampleForUpsampler(Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, float ratio, ref float fraction, int sampleCount)
{
// Currently a simple cubic interpolation, assuming duplicated values at edges.
// TODO: Discover and use algorithm that the switch uses.
int inputBufferIndex = 0;
int maxIndex = inputBuffer.Length - 1;
int cubicEnd = inputBuffer.Length - 3;
for (int i = 0; i < sampleCount; i++)
{
float s0, s1, s2, s3;
s1 = inputBuffer[inputBufferIndex];
if (inputBufferIndex == 0 || inputBufferIndex > cubicEnd)
{
// Clamp interplation values at the ends of the input buffer.
s0 = inputBuffer[Math.Max(0, inputBufferIndex - 1)];
s2 = inputBuffer[Math.Min(maxIndex, inputBufferIndex + 1)];
s3 = inputBuffer[Math.Min(maxIndex, inputBufferIndex + 2)];
}
else
{
s0 = inputBuffer[inputBufferIndex - 1];
s2 = inputBuffer[inputBufferIndex + 1];
s3 = inputBuffer[inputBufferIndex + 2];
}
float a = s3 - s2 - s0 + s1;
float b = s0 - s1 - a;
float c = s2 - s0;
float d = s1;
float f2 = fraction * fraction;
float f3 = f2 * fraction;
outputBuffer[i] = a * f3 + b * f2 + c * fraction + d;
fraction += ratio;
inputBufferIndex += (int)MathF.Truncate(fraction);
fraction -= (int)fraction;
}
}
}
}

175
Ryujinx.Audio/Renderer/Dsp/UpsamplerHelper.cs Normal file
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@ -0,0 +1,175 @@
using Ryujinx.Audio.Renderer.Server.Upsampler;
using Ryujinx.Common.Memory;
using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
namespace Ryujinx.Audio.Renderer.Dsp
{
public class UpsamplerHelper
{
private const int HistoryLength = UpsamplerBufferState.HistoryLength;
private const int FilterBankLength = 20;
// Bank0 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
private const int Bank0CenterIndex = 9;
private static readonly Array20<float> Bank1 = PrecomputeFilterBank(1.0f / 6.0f);
private static readonly Array20<float> Bank2 = PrecomputeFilterBank(2.0f / 6.0f);
private static readonly Array20<float> Bank3 = PrecomputeFilterBank(3.0f / 6.0f);
private static readonly Array20<float> Bank4 = PrecomputeFilterBank(4.0f / 6.0f);
private static readonly Array20<float> Bank5 = PrecomputeFilterBank(5.0f / 6.0f);
private static Array20<float> PrecomputeFilterBank(float offset)
{
float Sinc(float x)
{
if (x == 0)
{
return 1.0f;
}
return (MathF.Sin(MathF.PI * x) / (MathF.PI * x));
}
float BlackmanWindow(float x)
{
const float a = 0.18f;
const float a0 = 0.5f - 0.5f * a;
const float a1 = -0.5f;
const float a2 = 0.5f * a;
return a0 + a1 * MathF.Cos(2 * MathF.PI * x) + a2 * MathF.Cos(4 * MathF.PI * x);
}
Array20<float> result = new Array20<float>();
for (int i = 0; i < FilterBankLength; i++)
{
float x = (Bank0CenterIndex - i) + offset;
result[i] = Sinc(x) * BlackmanWindow(x / FilterBankLength + 0.5f);
}
return result;
}
// Polyphase upsampling algorithm
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Upsample(Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, int outputSampleCount, int inputSampleCount, ref UpsamplerBufferState state)
{
if (!state.Initialized)
{
state.Scale = inputSampleCount switch
{
40 => 6.0f,
80 => 3.0f,
160 => 1.5f,
_ => throw new ArgumentOutOfRangeException()
};
state.Initialized = true;
}
if (outputSampleCount == 0)
{
return;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
float DoFilterBank(ref UpsamplerBufferState state, in Array20<float> bank)
{
float result = 0.0f;
Debug.Assert(state.History.Length == HistoryLength);
Debug.Assert(bank.Length == FilterBankLength);
for (int j = 0; j < FilterBankLength; j++)
{
result += bank[j] * state.History[j];
}
return result;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
void NextInput(ref UpsamplerBufferState state, float input)
{
state.History.AsSpan().Slice(1).CopyTo(state.History.AsSpan());
state.History[HistoryLength - 1] = input;
}
int inputBufferIndex = 0;
switch (state.Scale)
{
case 6.0f:
for (int i = 0; i < outputSampleCount; i++)
{
switch (state.Phase)
{
case 0:
NextInput(ref state, inputBuffer[inputBufferIndex++]);
outputBuffer[i] = state.History[Bank0CenterIndex];
break;
case 1:
outputBuffer[i] = DoFilterBank(ref state, Bank1);
break;
case 2:
outputBuffer[i] = DoFilterBank(ref state, Bank2);
break;
case 3:
outputBuffer[i] = DoFilterBank(ref state, Bank3);
break;
case 4:
outputBuffer[i] = DoFilterBank(ref state, Bank4);
break;
case 5:
outputBuffer[i] = DoFilterBank(ref state, Bank5);
break;
}
state.Phase = (state.Phase + 1) % 6;
}
break;
case 3.0f:
for (int i = 0; i < outputSampleCount; i++)
{
switch (state.Phase)
{
case 0:
NextInput(ref state, inputBuffer[inputBufferIndex++]);
outputBuffer[i] = state.History[Bank0CenterIndex];
break;
case 1:
outputBuffer[i] = DoFilterBank(ref state, Bank2);
break;
case 2:
outputBuffer[i] = DoFilterBank(ref state, Bank4);
break;
}
state.Phase = (state.Phase + 1) % 3;
}
break;
case 1.5f:
// Upsample by 3 then decimate by 2.
for (int i = 0; i < outputSampleCount; i++)
{
switch (state.Phase)
{
case 0:
NextInput(ref state, inputBuffer[inputBufferIndex++]);
outputBuffer[i] = state.History[Bank0CenterIndex];
break;
case 1:
outputBuffer[i] = DoFilterBank(ref state, Bank4);
break;
case 2:
NextInput(ref state, inputBuffer[inputBufferIndex++]);
outputBuffer[i] = DoFilterBank(ref state, Bank2);
break;
}
state.Phase = (state.Phase + 1) % 3;
}
break;
default:
throw new ArgumentOutOfRangeException();
}
}
}
}

14
Ryujinx.Audio/Renderer/Server/Upsampler/UpsamplerBufferState.cs Normal file
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@ -0,0 +1,14 @@
using Ryujinx.Common.Memory;
namespace Ryujinx.Audio.Renderer.Server.Upsampler
{
public struct UpsamplerBufferState
{
public const int HistoryLength = 20;
public float Scale;
public Array20<float> History;
public bool Initialized;
public int Phase;
}
}

5
Ryujinx.Audio/Renderer/Server/Upsampler/UpsamplerState.cs
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@ -37,6 +37,11 @@ namespace Ryujinx.Audio.Renderer.Server.Upsampler
/// </summary>
public ushort[] InputBufferIndices;
/// <summary>
/// State of each input buffer index kept across invocations of the upsampler.
/// </summary>
public UpsamplerBufferState[] BufferStates;
/// <summary>
/// Create a new <see cref="UpsamplerState"/>.
/// </summary>