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Use a basic cubic interpolation for the audren upsampler (#3129)

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Before, it was selecting nearest neighbour, which sounded terrible. This is likely temporary til the upsampling algorithm used by the switch is reversed.

Fixes bad audio in Skyward Sword HD.
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riperiperi 2022-02-17 19:19:29 +00:00 committed by GitHub
parent 741db8e43d
commit 7e9011673b
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 28 additions and 5 deletions
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33
Ryujinx.Audio/Renderer/Dsp/ResamplerHelper.cs
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@ -600,19 +600,42 @@ namespace Ryujinx.Audio.Renderer.Dsp
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void ResampleForUpsampler(Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, float ratio, ref float fraction, int sampleCount)
{
// TODO: use a bandwidth filter to have better resampling.
// 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 outputData = inputBuffer[inputBufferIndex];
float s0, s1, s2, s3;
if (fraction > 1.0f)
s1 = inputBuffer[inputBufferIndex];
if (inputBufferIndex == 0 || inputBufferIndex > cubicEnd)
{
outputData = inputBuffer[inputBufferIndex + 1];
// 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];
}
outputBuffer[i] = outputData;
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);