From 06b83a58a6d60063cd5fad934aa7f3a75f0ce040 Mon Sep 17 00:00:00 2001
From: Maufeat <sahyno1996@gmail.com>
Date: Sat, 13 Dec 2025 19:44:41 +0100
Subject: [audio] correct biquad filter v2 parameters (#3142)

We had the same struct for v1 and v2 - this was tested only with MP4, should output correct sounds now and boot it.

Co-authored-by: MaranBr <maranbr@outlook.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3142
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Maufeat <sahyno1996@gmail.com>
Co-committed-by: Maufeat <sahyno1996@gmail.com>
---
 src/audio_core/renderer/command/command_buffer.cpp | 56 +++++++++++++++++++---
 1 file changed, 49 insertions(+), 7 deletions(-)

(limited to 'src/audio_core/renderer/command/command_buffer.cpp')

diff --git a/src/audio_core/renderer/command/command_buffer.cpp b/src/audio_core/renderer/command/command_buffer.cpp
index a0a574fc64..804aba438d 100644
--- a/src/audio_core/renderer/command/command_buffer.cpp
+++ b/src/audio_core/renderer/command/command_buffer.cpp
@@ -21,6 +21,15 @@
 
 namespace AudioCore::Renderer {
 
+namespace {
+constexpr f32 BiquadParameterFixedScaleQ14 = 16384.0f; // 1 << 14
+
+[[nodiscard]] inline s16 ToQ14Clamped(f32 v) {
+    const f32 scaled = std::clamp(v * BiquadParameterFixedScaleQ14, -32768.0f, 32767.0f);
+    return static_cast<s16>(scaled);
+}
+} // namespace
+
 template <typename T, CommandId Id>
 T& CommandBuffer::GenerateStart(const s32 node_id) {
     if (size + sizeof(T) >= command_list.size_bytes()) {
@@ -259,18 +268,42 @@ void CommandBuffer::GenerateBiquadFilterCommand(const s32 node_id, EffectInfoBas
                                                 const bool use_float_processing) {
     auto& cmd{GenerateStart<BiquadFilterCommand, CommandId::BiquadFilter>(node_id)};
 
-    const auto& parameter{
-        *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
     const auto state{reinterpret_cast<VoiceState::BiquadFilterState*>(
         effect_info.GetStateBuffer() + channel * sizeof(VoiceState::BiquadFilterState))};
 
-    cmd.input = buffer_offset + parameter.inputs[channel];
-    cmd.output = buffer_offset + parameter.outputs[channel];
+    if (behavior->IsEffectInfoVersion2Supported()) {
+        const auto& p{
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion2*>(effect_info.GetParameter())};
 
-    cmd.biquad.b = parameter.b;
-    cmd.biquad.a = parameter.a;
+        if (!IsChannelCountValid(p.channel_count) || channel < 0 || channel >= p.channel_count) {
+            return;
+        }
+
+        cmd.input = buffer_offset + p.inputs[channel];
+        cmd.output = buffer_offset + p.outputs[channel];
+
+        // Convert float coefficients to Q2.14 fixed-point as expected by the legacy DSP path.
+        cmd.biquad.b[0] = ToQ14Clamped(p.b[0]);
+        cmd.biquad.b[1] = ToQ14Clamped(p.b[1]);
+        cmd.biquad.b[2] = ToQ14Clamped(p.b[2]);
+        cmd.biquad.a[0] = ToQ14Clamped(p.a[0]);
+        cmd.biquad.a[1] = ToQ14Clamped(p.a[1]);
+    } else {
+        const auto& p{
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
 
-    // Effects use legacy fixed-point format
+        if (!IsChannelCountValid(p.channel_count) || channel < 0 || channel >= p.channel_count) {
+            return;
+        }
+
+        cmd.input = buffer_offset + p.inputs[channel];
+        cmd.output = buffer_offset + p.outputs[channel];
+
+        cmd.biquad.b = p.b;
+        cmd.biquad.a = p.a;
+    }
+
+    // Effects always use the fixed-point coefficient path on the DSP.
     cmd.use_float_coefficients = false;
 
     cmd.state = memory_pool->Translate(CpuAddr(state),
@@ -595,6 +628,15 @@ void CommandBuffer::GenerateCopyMixBufferCommand(const s32 node_id, EffectInfoBa
                                                  const s16 buffer_offset, const s8 channel) {
     auto& cmd{GenerateStart<CopyMixBufferCommand, CommandId::CopyMixBuffer>(node_id)};
 
+    if (behavior->IsEffectInfoVersion2Supported()) {
+        const auto& parameter_v2{
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion2*>(effect_info.GetParameter())};
+        cmd.input_index = buffer_offset + parameter_v2.inputs[channel];
+        cmd.output_index = buffer_offset + parameter_v2.outputs[channel];
+        GenerateEnd<CopyMixBufferCommand>(cmd);
+        return;
+    }
+
     const auto& parameter{
         *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
     cmd.input_index = buffer_offset + parameter.inputs[channel];
-- 
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