Update audio renderer to REV12: Add support for splitter biquad filter (#6813)

* Update audio renderer to REV12: Add support for splitter biquad filter

* Formatting

* Official names

* Update BiquadFilterState size + other fixes

* Update tests

* Update comment for version 2

* Size test for SplitterDestinationVersion2

* Should use Volume1 if no ramp

7 files changed, 522 insertions, 12 deletions

diff --git a/src/Ryujinx.Audio/Renderer/Dsp/BiquadFilterHelper.cs b/src/Ryujinx.Audio/Renderer/Dsp/BiquadFilterHelper.cs
index 1a51a1fb..31f614d6 100644
--- a/src/Ryujinx.Audio/Renderer/Dsp/BiquadFilterHelper.cs
+++ b/src/Ryujinx.Audio/Renderer/Dsp/BiquadFilterHelper.cs
@@ -16,10 +16,15 @@ namespace Ryujinx.Audio.Renderer.Dsp
         /// <param name="parameter">The biquad filter parameter</param>
         /// <param name="state">The biquad filter state</param>
         /// <param name="outputBuffer">The output buffer to write the result</param>
-        /// <param name="inputBuffer">The input buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
         /// <param name="sampleCount">The count of samples to process</param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void ProcessBiquadFilter(ref BiquadFilterParameter parameter, ref BiquadFilterState state, Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, uint sampleCount)
+        public static void ProcessBiquadFilter(
+            ref BiquadFilterParameter parameter,
+            ref BiquadFilterState state,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount)
         {
             float a0 = FixedPointHelper.ToFloat(parameter.Numerator[0], FixedPointPrecisionForParameter);
             float a1 = FixedPointHelper.ToFloat(parameter.Numerator[1], FixedPointPrecisionForParameter);
@@ -41,16 +46,111 @@ namespace Ryujinx.Audio.Renderer.Dsp
         }
 
         /// <summary>
+        /// Apply a single biquad filter and mix the result into the output buffer.
+        /// </summary>
+        /// <remarks>This is implemented with a direct form 1.</remarks>
+        /// <param name="parameter">The biquad filter parameter</param>
+        /// <param name="state">The biquad filter state</param>
+        /// <param name="outputBuffer">The output buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
+        /// <param name="sampleCount">The count of samples to process</param>
+        /// <param name="volume">Mix volume</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void ProcessBiquadFilterAndMix(
+            ref BiquadFilterParameter parameter,
+            ref BiquadFilterState state,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount,
+            float volume)
+        {
+            float a0 = FixedPointHelper.ToFloat(parameter.Numerator[0], FixedPointPrecisionForParameter);
+            float a1 = FixedPointHelper.ToFloat(parameter.Numerator[1], FixedPointPrecisionForParameter);
+            float a2 = FixedPointHelper.ToFloat(parameter.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b1 = FixedPointHelper.ToFloat(parameter.Denominator[0], FixedPointPrecisionForParameter);
+            float b2 = FixedPointHelper.ToFloat(parameter.Denominator[1], FixedPointPrecisionForParameter);
+
+            for (int i = 0; i < sampleCount; i++)
+            {
+                float input = inputBuffer[i];
+                float output = input * a0 + state.State0 * a1 + state.State1 * a2 + state.State2 * b1 + state.State3 * b2;
+
+                state.State1 = state.State0;
+                state.State0 = input;
+                state.State3 = state.State2;
+                state.State2 = output;
+
+                outputBuffer[i] += FloatingPointHelper.MultiplyRoundUp(output, volume);
+            }
+        }
+
+        /// <summary>
+        /// Apply a single biquad filter and mix the result into the output buffer with volume ramp.
+        /// </summary>
+        /// <remarks>This is implemented with a direct form 1.</remarks>
+        /// <param name="parameter">The biquad filter parameter</param>
+        /// <param name="state">The biquad filter state</param>
+        /// <param name="outputBuffer">The output buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
+        /// <param name="sampleCount">The count of samples to process</param>
+        /// <param name="volume">Initial mix volume</param>
+        /// <param name="ramp">Volume increment step</param>
+        /// <returns>Last filtered sample value</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static float ProcessBiquadFilterAndMixRamp(
+            ref BiquadFilterParameter parameter,
+            ref BiquadFilterState state,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount,
+            float volume,
+            float ramp)
+        {
+            float a0 = FixedPointHelper.ToFloat(parameter.Numerator[0], FixedPointPrecisionForParameter);
+            float a1 = FixedPointHelper.ToFloat(parameter.Numerator[1], FixedPointPrecisionForParameter);
+            float a2 = FixedPointHelper.ToFloat(parameter.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b1 = FixedPointHelper.ToFloat(parameter.Denominator[0], FixedPointPrecisionForParameter);
+            float b2 = FixedPointHelper.ToFloat(parameter.Denominator[1], FixedPointPrecisionForParameter);
+
+            float mixState = 0f;
+
+            for (int i = 0; i < sampleCount; i++)
+            {
+                float input = inputBuffer[i];
+                float output = input * a0 + state.State0 * a1 + state.State1 * a2 + state.State2 * b1 + state.State3 * b2;
+
+                state.State1 = state.State0;
+                state.State0 = input;
+                state.State3 = state.State2;
+                state.State2 = output;
+
+                mixState = FloatingPointHelper.MultiplyRoundUp(output, volume);
+
+                outputBuffer[i] += mixState;
+                volume += ramp;
+            }
+
+            return mixState;
+        }
+
+        /// <summary>
         /// Apply multiple biquad filter.
         /// </summary>
         /// <remarks>This is implemented with a direct form 1.</remarks>
         /// <param name="parameters">The biquad filter parameter</param>
         /// <param name="states">The biquad filter state</param>
         /// <param name="outputBuffer">The output buffer to write the result</param>
-        /// <param name="inputBuffer">The input buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
         /// <param name="sampleCount">The count of samples to process</param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void ProcessBiquadFilter(ReadOnlySpan<BiquadFilterParameter> parameters, Span<BiquadFilterState> states, Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, uint sampleCount)
+        public static void ProcessBiquadFilter(
+            ReadOnlySpan<BiquadFilterParameter> parameters,
+            Span<BiquadFilterState> states,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount)
         {
             for (int stageIndex = 0; stageIndex < parameters.Length; stageIndex++)
             {
@@ -67,7 +167,7 @@ namespace Ryujinx.Audio.Renderer.Dsp
 
                 for (int i = 0; i < sampleCount; i++)
                 {
-                    float input = inputBuffer[i];
+                    float input = stageIndex != 0 ? outputBuffer[i] : inputBuffer[i];
                     float output = input * a0 + state.State0 * a1 + state.State1 * a2 + state.State2 * b1 + state.State3 * b2;
 
                     state.State1 = state.State0;
@@ -79,5 +179,129 @@ namespace Ryujinx.Audio.Renderer.Dsp
                 }
             }
         }
+
+        /// <summary>
+        /// Apply double biquad filter and mix the result into the output buffer.
+        /// </summary>
+        /// <remarks>This is implemented with a direct form 1.</remarks>
+        /// <param name="parameters">The biquad filter parameter</param>
+        /// <param name="states">The biquad filter state</param>
+        /// <param name="outputBuffer">The output buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
+        /// <param name="sampleCount">The count of samples to process</param>
+        /// <param name="volume">Mix volume</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void ProcessDoubleBiquadFilterAndMix(
+            ref BiquadFilterParameter parameter0,
+            ref BiquadFilterParameter parameter1,
+            ref BiquadFilterState state0,
+            ref BiquadFilterState state1,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount,
+            float volume)
+        {
+            float a00 = FixedPointHelper.ToFloat(parameter0.Numerator[0], FixedPointPrecisionForParameter);
+            float a10 = FixedPointHelper.ToFloat(parameter0.Numerator[1], FixedPointPrecisionForParameter);
+            float a20 = FixedPointHelper.ToFloat(parameter0.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b10 = FixedPointHelper.ToFloat(parameter0.Denominator[0], FixedPointPrecisionForParameter);
+            float b20 = FixedPointHelper.ToFloat(parameter0.Denominator[1], FixedPointPrecisionForParameter);
+
+            float a01 = FixedPointHelper.ToFloat(parameter1.Numerator[0], FixedPointPrecisionForParameter);
+            float a11 = FixedPointHelper.ToFloat(parameter1.Numerator[1], FixedPointPrecisionForParameter);
+            float a21 = FixedPointHelper.ToFloat(parameter1.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b11 = FixedPointHelper.ToFloat(parameter1.Denominator[0], FixedPointPrecisionForParameter);
+            float b21 = FixedPointHelper.ToFloat(parameter1.Denominator[1], FixedPointPrecisionForParameter);
+
+            for (int i = 0; i < sampleCount; i++)
+            {
+                float input = inputBuffer[i];
+                float output = input * a00 + state0.State0 * a10 + state0.State1 * a20 + state0.State2 * b10 + state0.State3 * b20;
+
+                state0.State1 = state0.State0;
+                state0.State0 = input;
+                state0.State3 = state0.State2;
+                state0.State2 = output;
+
+                input = output;
+                output = input * a01 + state1.State0 * a11 + state1.State1 * a21 + state1.State2 * b11 + state1.State3 * b21;
+
+                state1.State1 = state1.State0;
+                state1.State0 = input;
+                state1.State3 = state1.State2;
+                state1.State2 = output;
+
+                outputBuffer[i] += FloatingPointHelper.MultiplyRoundUp(output, volume);
+            }
+        }
+
+        /// <summary>
+        /// Apply double biquad filter and mix the result into the output buffer with volume ramp.
+        /// </summary>
+        /// <remarks>This is implemented with a direct form 1.</remarks>
+        /// <param name="parameters">The biquad filter parameter</param>
+        /// <param name="states">The biquad filter state</param>
+        /// <param name="outputBuffer">The output buffer to write the result</param>
+        /// <param name="inputBuffer">The input buffer to read the samples from</param>
+        /// <param name="sampleCount">The count of samples to process</param>
+        /// <param name="volume">Initial mix volume</param>
+        /// <param name="ramp">Volume increment step</param>
+        /// <returns>Last filtered sample value</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static float ProcessDoubleBiquadFilterAndMixRamp(
+            ref BiquadFilterParameter parameter0,
+            ref BiquadFilterParameter parameter1,
+            ref BiquadFilterState state0,
+            ref BiquadFilterState state1,
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            uint sampleCount,
+            float volume,
+            float ramp)
+        {
+            float a00 = FixedPointHelper.ToFloat(parameter0.Numerator[0], FixedPointPrecisionForParameter);
+            float a10 = FixedPointHelper.ToFloat(parameter0.Numerator[1], FixedPointPrecisionForParameter);
+            float a20 = FixedPointHelper.ToFloat(parameter0.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b10 = FixedPointHelper.ToFloat(parameter0.Denominator[0], FixedPointPrecisionForParameter);
+            float b20 = FixedPointHelper.ToFloat(parameter0.Denominator[1], FixedPointPrecisionForParameter);
+
+            float a01 = FixedPointHelper.ToFloat(parameter1.Numerator[0], FixedPointPrecisionForParameter);
+            float a11 = FixedPointHelper.ToFloat(parameter1.Numerator[1], FixedPointPrecisionForParameter);
+            float a21 = FixedPointHelper.ToFloat(parameter1.Numerator[2], FixedPointPrecisionForParameter);
+
+            float b11 = FixedPointHelper.ToFloat(parameter1.Denominator[0], FixedPointPrecisionForParameter);
+            float b21 = FixedPointHelper.ToFloat(parameter1.Denominator[1], FixedPointPrecisionForParameter);
+
+            float mixState = 0f;
+
+            for (int i = 0; i < sampleCount; i++)
+            {
+                float input = inputBuffer[i];
+                float output = input * a00 + state0.State0 * a10 + state0.State1 * a20 + state0.State2 * b10 + state0.State3 * b20;
+
+                state0.State1 = state0.State0;
+                state0.State0 = input;
+                state0.State3 = state0.State2;
+                state0.State2 = output;
+
+                input = output;
+                output = input * a01 + state1.State0 * a11 + state1.State1 * a21 + state1.State2 * b11 + state1.State3 * b21;
+
+                state1.State1 = state1.State0;
+                state1.State0 = input;
+                state1.State3 = state1.State2;
+                state1.State2 = output;
+
+                mixState = FloatingPointHelper.MultiplyRoundUp(output, volume);
+
+                outputBuffer[i] += mixState;
+                volume += ramp;
+            }
+
+            return mixState;
+        }
     }
 }
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/Command/BiquadFilterAndMixCommand.cs b/src/Ryujinx.Audio/Renderer/Dsp/Command/BiquadFilterAndMixCommand.cs
new file mode 100644
index 00000000..106fc035
--- /dev/null
+++ b/src/Ryujinx.Audio/Renderer/Dsp/Command/BiquadFilterAndMixCommand.cs
@@ -0,0 +1,123 @@
+using Ryujinx.Audio.Renderer.Common;
+using Ryujinx.Audio.Renderer.Dsp.State;
+using Ryujinx.Audio.Renderer.Parameter;
+using System;
+
+namespace Ryujinx.Audio.Renderer.Dsp.Command
+{
+    public class BiquadFilterAndMixCommand : ICommand
+    {
+        public bool Enabled { get; set; }
+
+        public int NodeId { get; }
+
+        public CommandType CommandType => CommandType.BiquadFilterAndMix;
+
+        public uint EstimatedProcessingTime { get; set; }
+
+        public ushort InputBufferIndex { get; }
+        public ushort OutputBufferIndex { get; }
+
+        private BiquadFilterParameter _parameter;
+
+        public Memory<BiquadFilterState> BiquadFilterState { get; }
+        public Memory<BiquadFilterState> PreviousBiquadFilterState { get; }
+
+        public Memory<VoiceUpdateState> State { get; }
+
+        public int LastSampleIndex { get; }
+
+        public float Volume0 { get; }
+        public float Volume1 { get; }
+
+        public bool NeedInitialization { get; }
+        public bool HasVolumeRamp { get; }
+        public bool IsFirstMixBuffer { get; }
+
+        public BiquadFilterAndMixCommand(
+            float volume0,
+            float volume1,
+            uint inputBufferIndex,
+            uint outputBufferIndex,
+            int lastSampleIndex,
+            Memory<VoiceUpdateState> state,
+            ref BiquadFilterParameter filter,
+            Memory<BiquadFilterState> biquadFilterState,
+            Memory<BiquadFilterState> previousBiquadFilterState,
+            bool needInitialization,
+            bool hasVolumeRamp,
+            bool isFirstMixBuffer,
+            int nodeId)
+        {
+            Enabled = true;
+            NodeId = nodeId;
+
+            InputBufferIndex = (ushort)inputBufferIndex;
+            OutputBufferIndex = (ushort)outputBufferIndex;
+
+            _parameter = filter;
+            BiquadFilterState = biquadFilterState;
+            PreviousBiquadFilterState = previousBiquadFilterState;
+
+            State = state;
+            LastSampleIndex = lastSampleIndex;
+
+            Volume0 = volume0;
+            Volume1 = volume1;
+
+            NeedInitialization = needInitialization;
+            HasVolumeRamp = hasVolumeRamp;
+            IsFirstMixBuffer = isFirstMixBuffer;
+        }
+
+        public void Process(CommandList context)
+        {
+            ReadOnlySpan<float> inputBuffer = context.GetBuffer(InputBufferIndex);
+            Span<float> outputBuffer = context.GetBuffer(OutputBufferIndex);
+
+            if (NeedInitialization)
+            {
+                // If there is no previous state, initialize to zero.
+
+                BiquadFilterState.Span[0] = new BiquadFilterState();
+            }
+            else if (IsFirstMixBuffer)
+            {
+                // This is the first buffer, set previous state to current state.
+
+                PreviousBiquadFilterState.Span[0] = BiquadFilterState.Span[0];
+            }
+            else
+            {
+                // Rewind the current state by copying back the previous state.
+
+                BiquadFilterState.Span[0] = PreviousBiquadFilterState.Span[0];
+            }
+
+            if (HasVolumeRamp)
+            {
+                float volume = Volume0;
+                float ramp = (Volume1 - Volume0) / (int)context.SampleCount;
+
+                State.Span[0].LastSamples[LastSampleIndex] = BiquadFilterHelper.ProcessBiquadFilterAndMixRamp(
+                    ref _parameter,
+                    ref BiquadFilterState.Span[0],
+                    outputBuffer,
+                    inputBuffer,
+                    context.SampleCount,
+                    volume,
+                    ramp);
+            }
+            else
+            {
+                BiquadFilterHelper.ProcessBiquadFilterAndMix(
+                    ref _parameter,
+                    ref BiquadFilterState.Span[0],
+                    outputBuffer,
+                    inputBuffer,
+                    context.SampleCount,
+                    Volume1);
+            }
+        }
+    }
+}
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/Command/CommandType.cs b/src/Ryujinx.Audio/Renderer/Dsp/Command/CommandType.cs
index 098a04a0..de5c0ea2 100644
--- a/src/Ryujinx.Audio/Renderer/Dsp/Command/CommandType.cs
+++ b/src/Ryujinx.Audio/Renderer/Dsp/Command/CommandType.cs
@@ -30,8 +30,10 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
         CopyMixBuffer,
         LimiterVersion1,
         LimiterVersion2,
-        GroupedBiquadFilter,
+        MultiTapBiquadFilter,
         CaptureBuffer,
         Compressor,
+        BiquadFilterAndMix,
+        MultiTapBiquadFilterAndMix,
     }
 }
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/Command/MixRampGroupedCommand.cs b/src/Ryujinx.Audio/Renderer/Dsp/Command/MixRampGroupedCommand.cs
index 3c7dd63b..41ac84c1 100644
--- a/src/Ryujinx.Audio/Renderer/Dsp/Command/MixRampGroupedCommand.cs
+++ b/src/Ryujinx.Audio/Renderer/Dsp/Command/MixRampGroupedCommand.cs
@@ -24,7 +24,14 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
 
         public Memory<VoiceUpdateState> State { get; }
 
-        public MixRampGroupedCommand(uint mixBufferCount, uint inputBufferIndex, uint outputBufferIndex, Span<float> volume0, Span<float> volume1, Memory<VoiceUpdateState> state, int nodeId)
+        public MixRampGroupedCommand(
+            uint mixBufferCount,
+            uint inputBufferIndex,
+            uint outputBufferIndex,
+            ReadOnlySpan<float> volume0,
+            ReadOnlySpan<float> volume1,
+            Memory<VoiceUpdateState> state,
+            int nodeId)
         {
             Enabled = true;
             MixBufferCount = mixBufferCount;
@@ -48,7 +55,12 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static float ProcessMixRampGrouped(Span<float> outputBuffer, ReadOnlySpan<float> inputBuffer, float volume0, float volume1, int sampleCount)
+        private static float ProcessMixRampGrouped(
+            Span<float> outputBuffer,
+            ReadOnlySpan<float> inputBuffer,
+            float volume0,
+            float volume1,
+            int sampleCount)
         {
             float ramp = (volume1 - volume0) / sampleCount;
             float volume = volume0;
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/Command/MultiTapBiquadFilterAndMixCommand.cs b/src/Ryujinx.Audio/Renderer/Dsp/Command/MultiTapBiquadFilterAndMixCommand.cs
new file mode 100644
index 00000000..e359371b
--- /dev/null
+++ b/src/Ryujinx.Audio/Renderer/Dsp/Command/MultiTapBiquadFilterAndMixCommand.cs
@@ -0,0 +1,145 @@
+using Ryujinx.Audio.Renderer.Common;
+using Ryujinx.Audio.Renderer.Dsp.State;
+using Ryujinx.Audio.Renderer.Parameter;
+using System;
+
+namespace Ryujinx.Audio.Renderer.Dsp.Command
+{
+    public class MultiTapBiquadFilterAndMixCommand : ICommand
+    {
+        public bool Enabled { get; set; }
+
+        public int NodeId { get; }
+
+        public CommandType CommandType => CommandType.MultiTapBiquadFilterAndMix;
+
+        public uint EstimatedProcessingTime { get; set; }
+
+        public ushort InputBufferIndex { get; }
+        public ushort OutputBufferIndex { get; }
+
+        private BiquadFilterParameter _parameter0;
+        private BiquadFilterParameter _parameter1;
+
+        public Memory<BiquadFilterState> BiquadFilterState0 { get; }
+        public Memory<BiquadFilterState> BiquadFilterState1 { get; }
+        public Memory<BiquadFilterState> PreviousBiquadFilterState0 { get; }
+        public Memory<BiquadFilterState> PreviousBiquadFilterState1 { get; }
+
+        public Memory<VoiceUpdateState> State { get; }
+
+        public int LastSampleIndex { get; }
+
+        public float Volume0 { get; }
+        public float Volume1 { get; }
+
+        public bool NeedInitialization0 { get; }
+        public bool NeedInitialization1 { get; }
+        public bool HasVolumeRamp { get; }
+        public bool IsFirstMixBuffer { get; }
+
+        public MultiTapBiquadFilterAndMixCommand(
+            float volume0,
+            float volume1,
+            uint inputBufferIndex,
+            uint outputBufferIndex,
+            int lastSampleIndex,
+            Memory<VoiceUpdateState> state,
+            ref BiquadFilterParameter filter0,
+            ref BiquadFilterParameter filter1,
+            Memory<BiquadFilterState> biquadFilterState0,
+            Memory<BiquadFilterState> biquadFilterState1,
+            Memory<BiquadFilterState> previousBiquadFilterState0,
+            Memory<BiquadFilterState> previousBiquadFilterState1,
+            bool needInitialization0,
+            bool needInitialization1,
+            bool hasVolumeRamp,
+            bool isFirstMixBuffer,
+            int nodeId)
+        {
+            Enabled = true;
+            NodeId = nodeId;
+
+            InputBufferIndex = (ushort)inputBufferIndex;
+            OutputBufferIndex = (ushort)outputBufferIndex;
+
+            _parameter0 = filter0;
+            _parameter1 = filter1;
+            BiquadFilterState0 = biquadFilterState0;
+            BiquadFilterState1 = biquadFilterState1;
+            PreviousBiquadFilterState0 = previousBiquadFilterState0;
+            PreviousBiquadFilterState1 = previousBiquadFilterState1;
+
+            State = state;
+            LastSampleIndex = lastSampleIndex;
+
+            Volume0 = volume0;
+            Volume1 = volume1;
+
+            NeedInitialization0 = needInitialization0;
+            NeedInitialization1 = needInitialization1;
+            HasVolumeRamp = hasVolumeRamp;
+            IsFirstMixBuffer = isFirstMixBuffer;
+        }
+
+        private void UpdateState(Memory<BiquadFilterState> state, Memory<BiquadFilterState> previousState, bool needInitialization)
+        {
+            if (needInitialization)
+            {
+                // If there is no previous state, initialize to zero.
+
+                state.Span[0] = new BiquadFilterState();
+            }
+            else if (IsFirstMixBuffer)
+            {
+                // This is the first buffer, set previous state to current state.
+
+                previousState.Span[0] = state.Span[0];
+            }
+            else
+            {
+                // Rewind the current state by copying back the previous state.
+
+                state.Span[0] = previousState.Span[0];
+            }
+        }
+
+        public void Process(CommandList context)
+        {
+            ReadOnlySpan<float> inputBuffer = context.GetBuffer(InputBufferIndex);
+            Span<float> outputBuffer = context.GetBuffer(OutputBufferIndex);
+
+            UpdateState(BiquadFilterState0, PreviousBiquadFilterState0, NeedInitialization0);
+            UpdateState(BiquadFilterState1, PreviousBiquadFilterState1, NeedInitialization1);
+
+            if (HasVolumeRamp)
+            {
+                float volume = Volume0;
+                float ramp = (Volume1 - Volume0) / (int)context.SampleCount;
+
+                State.Span[0].LastSamples[LastSampleIndex] = BiquadFilterHelper.ProcessDoubleBiquadFilterAndMixRamp(
+                    ref _parameter0,
+                    ref _parameter1,
+                    ref BiquadFilterState0.Span[0],
+                    ref BiquadFilterState1.Span[0],
+                    outputBuffer,
+                    inputBuffer,
+                    context.SampleCount,
+                    volume,
+                    ramp);
+            }
+            else
+            {
+                BiquadFilterHelper.ProcessDoubleBiquadFilterAndMix(
+                    ref _parameter0,
+                    ref _parameter1,
+                    ref BiquadFilterState0.Span[0],
+                    ref BiquadFilterState1.Span[0],
+                    outputBuffer,
+                    inputBuffer,
+                    context.SampleCount,
+                    Volume1);
+            }
+        }
+    }
+}
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/Command/GroupedBiquadFilterCommand.cs b/src/Ryujinx.Audio/Renderer/Dsp/Command/MultiTapBiquadFilterCommand.cs
index 7af851bd..e159f8ef 100644
--- a/src/Ryujinx.Audio/Renderer/Dsp/Command/GroupedBiquadFilterCommand.cs
+++ b/src/Ryujinx.Audio/Renderer/Dsp/Command/MultiTapBiquadFilterCommand.cs
@@ -4,13 +4,13 @@ using System;
 
 namespace Ryujinx.Audio.Renderer.Dsp.Command
 {
-    public class GroupedBiquadFilterCommand : ICommand
+    public class MultiTapBiquadFilterCommand : ICommand
     {
         public bool Enabled { get; set; }
 
         public int NodeId { get; }
 
-        public CommandType CommandType => CommandType.GroupedBiquadFilter;
+        public CommandType CommandType => CommandType.MultiTapBiquadFilter;
 
         public uint EstimatedProcessingTime { get; set; }
 
@@ -20,7 +20,7 @@ namespace Ryujinx.Audio.Renderer.Dsp.Command
         private readonly int _outputBufferIndex;
         private readonly bool[] _isInitialized;
 
-        public GroupedBiquadFilterCommand(int baseIndex, ReadOnlySpan<BiquadFilterParameter> filters, Memory<BiquadFilterState> biquadFilterStateMemory, int inputBufferOffset, int outputBufferOffset, ReadOnlySpan<bool> isInitialized, int nodeId)
+        public MultiTapBiquadFilterCommand(int baseIndex, ReadOnlySpan<BiquadFilterParameter> filters, Memory<BiquadFilterState> biquadFilterStateMemory, int inputBufferOffset, int outputBufferOffset, ReadOnlySpan<bool> isInitialized, int nodeId)
         {
             _parameters = filters.ToArray();
             _biquadFilterStates = biquadFilterStateMemory;
diff --git a/src/Ryujinx.Audio/Renderer/Dsp/State/BiquadFilterState.cs b/src/Ryujinx.Audio/Renderer/Dsp/State/BiquadFilterState.cs
index f9a32b3f..58a2d9cc 100644
--- a/src/Ryujinx.Audio/Renderer/Dsp/State/BiquadFilterState.cs
+++ b/src/Ryujinx.Audio/Renderer/Dsp/State/BiquadFilterState.cs
@@ -2,12 +2,16 @@ using System.Runtime.InteropServices;
 
 namespace Ryujinx.Audio.Renderer.Dsp.State
 {
-    [StructLayout(LayoutKind.Sequential, Pack = 1, Size = 0x10)]
+    [StructLayout(LayoutKind.Sequential, Pack = 1, Size = 0x20)]
     public struct BiquadFilterState
     {
         public float State0;
         public float State1;
         public float State2;
         public float State3;
+        public float State4;
+        public float State5;
+        public float State6;
+        public float State7;
     }
 }