[Audio]: Improve BiquadFilter

src/audio_core/renderer/command/command_buffer.cpp

@@ -227,6 +227,133 @@ void CommandBuffer::GenerateBiquadFilterCommand(const s32 node_id, VoiceInfo& vo
                                                 const s16 buffer_count, const s8 channel,
                                                 const u32 biquad_index,
                                                 const bool use_float_processing) {
+    const bool is_v2 = behavior && behavior->IsEffectInfoVersion2Supported();
+
+    // Handle ParameterVersion2 (REV15+)
+    if (is_v2) {
+        const auto& param_v2{
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion2*>(effect_info.GetParameter())};
+
+        // Validate channel bounds
+        if (channel < 0 || channel >= param_v2.channel_count) {
+            return;
+        }
+
+        // Check state field - if state is out of valid range, generate copy command instead
+        if (static_cast<u8>(param_v2.state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+            GenerateCopyMixBufferCommand(node_id, effect_info, buffer_offset, channel);
+            return;
+        }
+
+        // Validate raw buffer indices before adding offset (similar to Ryujinx's ArgumentOutOfRange check)
+        const s8 raw_input = param_v2.inputs[channel];
+        const s8 raw_output = param_v2.outputs[channel];
+
+        // Validate raw indices are within reasonable bounds (negative values are allowed for unused channels)
+        // Maximum reasonable buffer index is typically 24-32, use 64 as a safe upper bound
+        constexpr s8 MaxReasonableBufferIndex = 64;
+        if (raw_input < -1 || raw_input >= MaxReasonableBufferIndex) {
+            LOG_WARNING(Service_Audio,
+                        "BiquadFilterCommand: Skipping command generation - raw input index out of range ({})",
+                        raw_input);
+            return;
+        }
+        if (raw_output < -1 || raw_output >= MaxReasonableBufferIndex) {
+            LOG_WARNING(Service_Audio,
+                        "BiquadFilterCommand: Skipping command generation - raw output index out of range ({})",
+                        raw_output);
+            return;
+        }
+
+        const s16 input_index = buffer_offset + raw_input;
+        const s16 output_index = buffer_offset + raw_output;
+
+        // Validate final buffer indices
+        if (input_index < 0) {
+            LOG_WARNING(Service_Audio,
+                        "BiquadFilterCommand: Skipping command generation - invalid input index ({})",
+                        input_index);
+            return;
+        }
+
+        const s16 effective_output = (output_index < 0) ? input_index : output_index;
+        if (output_index < 0) {
+            LOG_WARNING(Service_Audio,
+                        "BiquadFilterCommand: Invalid output index ({}), using input ({}) for in-place "
+                        "processing",
+                        output_index, input_index);
+        }
+
+        auto& cmd{GenerateStart<BiquadFilterCommand, CommandId::BiquadFilter>(node_id)};
+
+        cmd.input = input_index;
+        cmd.output = effective_output;
+
+        // Convert fixed-point coefficients (Q14 format) to float for REV15+ float processing
+        // Q14 means 14 fractional bits, so divide by 2^14 = 16384.0f
+        constexpr f32 q14_scale = 16384.0f;
+        cmd.biquad_float.numerator[0] = static_cast<f32>(param_v2.b[0]) / q14_scale;
+        cmd.biquad_float.numerator[1] = static_cast<f32>(param_v2.b[1]) / q14_scale;
+        cmd.biquad_float.numerator[2] = static_cast<f32>(param_v2.b[2]) / q14_scale;
+        cmd.biquad_float.denominator[0] = static_cast<f32>(param_v2.a[0]) / q14_scale;
+        cmd.biquad_float.denominator[1] = static_cast<f32>(param_v2.a[1]) / q14_scale;
+        cmd.use_float_coefficients = true;
+
+        // Translate state buffer - state pointer is already per-channel, so translate one state only
+        const auto state{reinterpret_cast<VoiceState::BiquadFilterState*>(
+            effect_info.GetStateBuffer() + channel * sizeof(VoiceState::BiquadFilterState))};
+        cmd.state = memory_pool->Translate(CpuAddr(state), sizeof(VoiceState::BiquadFilterState));
+
+        cmd.needs_init = needs_init;
+        cmd.use_float_processing = use_float_processing;
+
+        GenerateEnd<BiquadFilterCommand>(cmd);
+        return;
+    }
+
+    // Handle ParameterVersion1 (legacy)
+    const auto& param_v1{
+        *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
+
+    // Validate raw buffer indices before adding offset (similar to Ryujinx's ArgumentOutOfRange check)
+    const s8 raw_input = param_v1.inputs[channel];
+    const s8 raw_output = param_v1.outputs[channel];
+
+    // Validate raw indices are within reasonable bounds (negative values are allowed for unused channels)
+    // Maximum reasonable buffer index is typically 24-32, use 64 as a safe upper bound
+    constexpr s8 MaxReasonableBufferIndex = 64;
+    if (raw_input < -1 || raw_input >= MaxReasonableBufferIndex) {
+        LOG_WARNING(Service_Audio,
+                    "BiquadFilterCommand: Skipping command generation - raw input index out of range ({})",
+                    raw_input);
+        return;
+    }
+    if (raw_output < -1 || raw_output >= MaxReasonableBufferIndex) {
+        LOG_WARNING(Service_Audio,
+                    "BiquadFilterCommand: Skipping command generation - raw output index out of range ({})",
+                    raw_output);
+        return;
+    }
+
+    const s16 input_index = buffer_offset + raw_input;
+    const s16 output_index = buffer_offset + raw_output;
+
+    // Validate and correct buffer indices
+    if (input_index < 0) {
+        LOG_WARNING(Service_Audio,
+                    "BiquadFilterCommand: Skipping command generation - invalid input index ({})",
+                    input_index);
+        return;
+    }
+
+    const s16 effective_output = (output_index < 0) ? input_index : output_index;
+    if (output_index < 0) {
+        LOG_WARNING(Service_Audio,
+                    "BiquadFilterCommand: Invalid output index ({}), using input ({}) for in-place "
+                    "processing",
+                    output_index, input_index);
+    }
+
     auto& cmd{GenerateStart<BiquadFilterCommand, CommandId::BiquadFilter>(node_id)};
 
     cmd.input = buffer_count + channel;
@@ -301,20 +428,15 @@ void CommandBuffer::GenerateBiquadFilterCommand(const s32 node_id, EffectInfoBas
 
     auto& cmd{GenerateStart<BiquadFilterCommand, CommandId::BiquadFilter>(node_id)};
 
-    const auto& parameter{
+    cmd.input = input_index;
-        *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
+    cmd.output = effective_output;
-    const auto state{reinterpret_cast<VoiceState::BiquadFilterState*>(
+    cmd.biquad.b = param_v1.b;
-        effect_info.GetStateBuffer() + channel * sizeof(VoiceState::BiquadFilterState))};
+    cmd.biquad.a = param_v1.a;
-
-    cmd.input = buffer_offset + parameter.inputs[channel];
-    cmd.output = buffer_offset + parameter.outputs[channel];
-
-    cmd.biquad.b = parameter.b;
-    cmd.biquad.a = parameter.a;
-
-    // Effects use legacy fixed-point format
     cmd.use_float_coefficients = false;
 
+    // Translate state buffer address for DSP (v1 uses full buffer size)
+    const auto state{reinterpret_cast<VoiceState::BiquadFilterState*>(
+        effect_info.GetStateBuffer() + channel * sizeof(VoiceState::BiquadFilterState))};
     cmd.state = memory_pool->Translate(CpuAddr(state),
                                        MaxBiquadFilters * sizeof(VoiceState::BiquadFilterState));
 
@@ -649,10 +771,18 @@ void CommandBuffer::GenerateCopyMixBufferCommand(const s32 node_id, EffectInfoBa
 
     auto& cmd{GenerateStart<CopyMixBufferCommand, CommandId::CopyMixBuffer>(node_id)};
 
-    const auto& parameter{
+    // Extract buffer indices based on parameter version
-        *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
+    if (behavior && behavior->IsEffectInfoVersion2Supported()) {
-    cmd.input_index = buffer_offset + parameter.inputs[channel];
+        const auto& param_v2{
-    cmd.output_index = buffer_offset + parameter.outputs[channel];
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion2*>(effect_info.GetParameter())};
+        cmd.input_index = buffer_offset + param_v2.inputs[channel];
+        cmd.output_index = buffer_offset + param_v2.outputs[channel];
+    } else {
+        const auto& param_v1{
+            *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
+        cmd.input_index = buffer_offset + param_v1.inputs[channel];
+        cmd.output_index = buffer_offset + param_v1.outputs[channel];
+    }
 
     GenerateEnd<CopyMixBufferCommand>(cmd);
 }

src/audio_core/renderer/command/command_generator.cpp

@@ -1,6 +1,8 @@
 // SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <algorithm>
+
 #include "audio_core/common/audio_renderer_parameter.h"
 #include "audio_core/renderer/behavior/behavior_info.h"
 #include "audio_core/renderer/command/command_buffer.h"
@@ -361,30 +363,83 @@ void CommandGenerator::GenerateAuxCommand(const s16 buffer_offset, EffectInfoBas
 void CommandGenerator::GenerateBiquadFilterEffectCommand(const s16 buffer_offset,
                                                          EffectInfoBase& effect_info,
                                                          const s32 node_id) {
-
+    // Handle ParameterVersion2 (REV15+)
     if (render_context.behavior->IsEffectInfoVersion2Supported()) {
-        const auto& parameter_v2{
+        const auto& param_v2{
             *reinterpret_cast<BiquadFilterInfo::ParameterVersion2*>(effect_info.GetParameter())};
-        const bool needs_init = false;
+
+        // Early return if effect is disabled or parameters are invalid
+        if (!effect_info.IsEnabled()) {
+            return;
+        }
+
+        // Validate channel count to prevent out-of-bounds access
+        const s8 channel_count = param_v2.channel_count;
+        if (channel_count < 0 || static_cast<u32>(channel_count) > MaxChannels) {
+            LOG_WARNING(Service_Audio, "BiquadFilterEffectCommand: Invalid v2 channel_count {}, skipping",
+                        channel_count);
+            return;
+        }
+
+        // Validate parameter state
+        if (static_cast<u8>(param_v2.state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterEffectCommand: Invalid v2 parameter state {}, skipping",
+                        static_cast<u8>(param_v2.state));
+            return;
+        }
+
+        // Determine if initialization is needed based on state (similar to v1)
+        bool needs_init = false;
+        switch (param_v2.state) {
+        case EffectInfoBase::ParameterState::Initialized:
+            needs_init = true;
+            break;
+        case EffectInfoBase::ParameterState::Updating:
+        case EffectInfoBase::ParameterState::Updated:
+            if (render_context.behavior->IsBiquadFilterEffectStateClearBugFixed()) {
+                needs_init = false;
+            } else {
+                needs_init = param_v2.state == EffectInfoBase::ParameterState::Updating;
+            }
+            break;
+        default:
+            needs_init = false;
+            break;
+        }
+
         const bool use_float_processing = render_context.behavior->UseBiquadFilterFloatProcessing();
-        const s8 channels = parameter_v2.channel_count > 0 ? parameter_v2.channel_count : 2;
+
-        if (effect_info.IsEnabled()) {
+        // Generate commands for each active channel
-            for (s8 channel = 0; channel < channels; channel++) {
+        for (s8 channel = 0; channel < channel_count; channel++) {
-                command_buffer.GenerateBiquadFilterCommand(
+            command_buffer.GenerateBiquadFilterCommand(
-                    node_id, effect_info, buffer_offset, channel, needs_init, use_float_processing);
+                node_id, effect_info, buffer_offset, channel, needs_init, use_float_processing);
-            }
-        } else {
-            for (s8 channel = 0; channel < channels; channel++) {
-                command_buffer.GenerateCopyMixBufferCommand(node_id, effect_info, buffer_offset,
-                                                            channel);
-            }
         }
         return;
     }
 
-    const auto& parameter{
+    auto& parameter{
         *reinterpret_cast<BiquadFilterInfo::ParameterVersion1*>(effect_info.GetParameter())};
-    if (effect_info.IsEnabled()) {
+
+    // If effect is disabled (e.g., due to corrupted parameters), skip command generation
+    if (!effect_info.IsEnabled()) {
+        return;
+    }
+
+    // Validate parameters - if corrupted, skip command generation to prevent audio issues
+    if (parameter.channel_count < 0 || static_cast<u32>(parameter.channel_count) > MaxChannels) {
+        LOG_WARNING(Service_Audio, "BiquadFilterEffectCommand: Invalid channel_count {}, skipping command generation",
+                    parameter.channel_count);
+        return;
+    }
+
+    if (static_cast<u8>(parameter.state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+        LOG_WARNING(Service_Audio, "BiquadFilterEffectCommand: Invalid parameter state {}, skipping command generation",
+                    static_cast<u8>(parameter.state));
+        return;
+    }
+
+    // Effect is enabled and parameters are valid - generate commands
+    {
         bool needs_init{false};
 
         switch (parameter.state) {
@@ -400,8 +455,10 @@ void CommandGenerator::GenerateBiquadFilterEffectCommand(const s16 buffer_offset
             }
             break;
         default:
-            LOG_ERROR(Service_Audio, "Invalid biquad parameter state {}",
+            // Should not reach here after validation, but handle gracefully
-                      static_cast<u32>(parameter.state));
+            LOG_WARNING(Service_Audio, "BiquadFilterEffectCommand: Unexpected state {}, treating as Updated",
+                        static_cast<u8>(parameter.state));
+            needs_init = false;
             break;
         }
 
@@ -410,11 +467,6 @@ void CommandGenerator::GenerateBiquadFilterEffectCommand(const s16 buffer_offset
                 node_id, effect_info, buffer_offset, channel, needs_init,
                 render_context.behavior->UseBiquadFilterFloatProcessing());
         }
-    } else {
-        for (s8 channel = 0; channel < parameter.channel_count; channel++) {
-            command_buffer.GenerateCopyMixBufferCommand(node_id, effect_info, buffer_offset,
-                                                        channel);
-        }
     }
 }
 

src/audio_core/renderer/command/effect/biquad_filter.cpp

@@ -27,25 +27,28 @@ void ApplyBiquadFilterFloat(std::span<s32> output, std::span<const s32> input,
                          Common::FixedPoint<50, 14>::from_base(b_[2]).to_double()};
     std::array<f64, 2> a{Common::FixedPoint<50, 14>::from_base(a_[0]).to_double(),
                          Common::FixedPoint<50, 14>::from_base(a_[1]).to_double()};
-    std::array<f64, 4> s{Common::BitCast<f64>(state.s0), Common::BitCast<f64>(state.s1),
+
-                         Common::BitCast<f64>(state.s2), Common::BitCast<f64>(state.s3)};
+    // Direct Form 2 uses only 2 state variables (s0, s1)
+    // s2 and s3 are unused in Direct Form 2
+    f64 s0{Common::BitCast<f64>(state.s0)};
+    f64 s1{Common::BitCast<f64>(state.s1)};
 
     for (u32 i = 0; i < sample_count; i++) {
         f64 in_sample{static_cast<f64>(input[i])};
-        auto sample{in_sample * b[0] + s[0] * b[1] + s[1] * b[2] + s[2] * a[0] + s[3] * a[1]};
+        f64 sample{in_sample * b[0] + s0};
 
         output[i] = static_cast<s32>(std::clamp(sample, min, max));
 
-        s[1] = s[0];
+        // Update state using Direct Form 2
-        s[0] = in_sample;
+        s0 = in_sample * b[1] + sample * a[0] + s1;
-        s[3] = s[2];
+        s1 = in_sample * b[2] + sample * a[1];
-        s[2] = sample;
     }
 
-    state.s0 = Common::BitCast<s64>(s[0]);
+    state.s0 = Common::BitCast<s64>(s0);
-    state.s1 = Common::BitCast<s64>(s[1]);
+    state.s1 = Common::BitCast<s64>(s1);
-    state.s2 = Common::BitCast<s64>(s[2]);
+    // s2 and s3 are unused in Direct Form 2, but we keep them zeroed for consistency
-    state.s3 = Common::BitCast<s64>(s[3]);
+    state.s2 = 0;
+    state.s3 = 0;
 }
 
 /**
@@ -57,29 +60,30 @@ void ApplyBiquadFilterFloat2(std::span<s32> output, std::span<const s32> input,
     constexpr f64 min{std::numeric_limits<s32>::min()};
     constexpr f64 max{std::numeric_limits<s32>::max()};
 
-    std::array<f64, 3> b_double{static_cast<f64>(b[0]), static_cast<f64>(b[1]),
+    std::array<f64, 3> b_double{static_cast<f64>(b[0]), static_cast<f64>(b[1]), static_cast<f64>(b[2])};
-                                static_cast<f64>(b[2])};
     std::array<f64, 2> a_double{static_cast<f64>(a[0]), static_cast<f64>(a[1])};
-    std::array<f64, 4> s{Common::BitCast<f64>(state.s0), Common::BitCast<f64>(state.s1),
+
-                         Common::BitCast<f64>(state.s2), Common::BitCast<f64>(state.s3)};
+    // Direct Form 2 uses only 2 state variables (s0, s1)
+    // s2 and s3 are unused in Direct Form 2
+    f64 s0{Common::BitCast<f64>(state.s0)};
+    f64 s1{Common::BitCast<f64>(state.s1)};
 
     for (u32 i = 0; i < sample_count; i++) {
         f64 in_sample{static_cast<f64>(input[i])};
-        auto sample{in_sample * b_double[0] + s[0] * b_double[1] + s[1] * b_double[2] +
+        f64 sample{in_sample * b_double[0] + s0};
-                    s[2] * a_double[0] + s[3] * a_double[1]};
 
         output[i] = static_cast<s32>(std::clamp(sample, min, max));
 
-        s[1] = s[0];
+        // Update state using Direct Form 2
-        s[0] = in_sample;
+        s0 = in_sample * b_double[1] + sample * a_double[0] + s1;
-        s[3] = s[2];
+        s1 = in_sample * b_double[2] + sample * a_double[1];
-        s[2] = sample;
     }
 
-    state.s0 = Common::BitCast<s64>(s[0]);
+    state.s0 = Common::BitCast<s64>(s0);
-    state.s1 = Common::BitCast<s64>(s[1]);
+    state.s1 = Common::BitCast<s64>(s1);
-    state.s2 = Common::BitCast<s64>(s[2]);
+    // s2 and s3 are unused in Direct Form 2, but we keep them zeroed for consistency
-    state.s3 = Common::BitCast<s64>(s[3]);
+    state.s2 = 0;
+    state.s3 = 0;
 }
 
 /**
@@ -118,21 +122,58 @@ void BiquadFilterCommand::Dump(
 }
 
 void BiquadFilterCommand::Process(const AudioRenderer::CommandListProcessor& processor) {
+    if (state == 0) {
+        LOG_ERROR(Service_Audio, "BiquadFilterCommand: Invalid state pointer (null)");
+        return;
+    }
+
     auto state_{reinterpret_cast<VoiceState::BiquadFilterState*>(state)};
     if (needs_init) {
         *state_ = {};
     }
 
+    // Validate buffer indices and bounds
+    if (input < 0 || processor.sample_count == 0) {
+        LOG_ERROR(Service_Audio,
+                  "BiquadFilterCommand: Invalid input buffer index or sample count - input={}, "
+                  "sample_count={}",
+                  input, processor.sample_count);
+        return;
+    }
+
+    // If output is invalid but input is valid, use input as output (in-place processing)
+    s16 effective_output = output;
+    if (output < 0) {
+        LOG_WARNING(Service_Audio,
+                    "BiquadFilterCommand: Invalid output buffer index ({}), using input ({}) for "
+                    "in-place processing",
+                    output, input);
+        effective_output = input;
+    }
+
+    const u64 input_offset = static_cast<u64>(input) * processor.sample_count;
+    const u64 output_offset = static_cast<u64>(effective_output) * processor.sample_count;
+
+    if (input_offset + processor.sample_count > processor.mix_buffers.size() ||
+        output_offset + processor.sample_count > processor.mix_buffers.size()) {
+        LOG_ERROR(Service_Audio,
+                  "BiquadFilterCommand: Buffer indices out of bounds - input_offset={}, "
+                  "output_offset={}, sample_count={}, buffer_size={}",
+                  input_offset, output_offset, processor.sample_count,
+                  processor.mix_buffers.size());
+        return;
+    }
+
     auto input_buffer{
-        processor.mix_buffers.subspan(input * processor.sample_count, processor.sample_count)};
+        processor.mix_buffers.subspan(input_offset, processor.sample_count)};
     auto output_buffer{
-        processor.mix_buffers.subspan(output * processor.sample_count, processor.sample_count)};
+        processor.mix_buffers.subspan(output_offset, processor.sample_count)};
 
     if (use_float_processing) {
         // REV15+: Use native float coefficients if available
         if (use_float_coefficients) {
             ApplyBiquadFilterFloat2(output_buffer, input_buffer, biquad_float.numerator,
-                                    biquad_float.denominator, *state_, processor.sample_count);
+                                   biquad_float.denominator, *state_, processor.sample_count);
         } else {
             ApplyBiquadFilterFloat(output_buffer, input_buffer, biquad.b, biquad.a, *state_,
                                    processor.sample_count);
@@ -144,6 +185,44 @@ void BiquadFilterCommand::Process(const AudioRenderer::CommandListProcessor& pro
 }
 
 bool BiquadFilterCommand::Verify(const AudioRenderer::CommandListProcessor& processor) {
+    // Validate state pointer
+    if (state == 0) {
+        LOG_ERROR(Service_Audio, "BiquadFilterCommand: Invalid state pointer (null)");
+        return false;
+    }
+
+    // Validate input buffer index (required)
+    if (input < 0) {
+        LOG_ERROR(Service_Audio, "BiquadFilterCommand: Invalid input buffer index - input={}", input);
+        return false;
+    }
+
+    // Output can be invalid - we'll handle it by using input as output (in-place processing)
+    // So we don't fail verification if only output is invalid
+    s16 effective_output = output;
+    if (output < 0) {
+        effective_output = input;
+    }
+
+    if (processor.sample_count == 0) {
+        LOG_ERROR(Service_Audio, "BiquadFilterCommand: Invalid sample count - sample_count={}",
+                  processor.sample_count);
+        return false;
+    }
+
+    const u64 input_offset = static_cast<u64>(input) * processor.sample_count;
+    const u64 output_offset = static_cast<u64>(effective_output) * processor.sample_count;
+
+    if (input_offset + processor.sample_count > processor.mix_buffers.size() ||
+        output_offset + processor.sample_count > processor.mix_buffers.size()) {
+        LOG_ERROR(Service_Audio,
+                  "BiquadFilterCommand: Buffer indices out of bounds - input_offset={}, "
+                  "output_offset={}, sample_count={}, buffer_size={}",
+                  input_offset, output_offset, processor.sample_count,
+                  processor.mix_buffers.size());
+        return false;
+    }
+
     return true;
 }
 

src/audio_core/renderer/effect/biquad_filter.cpp

@@ -1,6 +1,8 @@
 // SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <algorithm>
+
 #include "audio_core/renderer/effect/biquad_filter.h"
 
 namespace AudioCore::Renderer {
@@ -11,9 +13,44 @@ void BiquadFilterInfo::Update(BehaviorInfo::ErrorInfo& error_info,
     auto params{reinterpret_cast<ParameterVersion1*>(parameter.data())};
 
     std::memcpy(params, in_specific, sizeof(ParameterVersion1));
+    // Check for corrupted parameters - if detected, disable the effect to prevent audio issues
+    bool parameters_valid = true;
+
+    // Validate channel_count
+    if (params->channel_count < 0 || static_cast<u32>(params->channel_count) > MaxChannels) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid channel_count {}, disabling effect",
+                    params->channel_count);
+        parameters_valid = false;
+    }
+
+    // Validate parameter state
+    if (static_cast<u8>(params->state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid parameter state {}, disabling effect",
+                    static_cast<u8>(params->state));
+        parameters_valid = false;
+    }
+
+    // Validate input/output buffer indices
+    for (s8 i = 0; static_cast<u32>(i) < MaxChannels && parameters_valid; i++) {
+        // Negative values are allowed (indicate unused channels), but check for out-of-range values
+        if (params->inputs[i] < -1 || params->inputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid input buffer index {} for channel {}, disabling effect",
+                        params->inputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+        if (params->outputs[i] < -1 || params->outputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid output buffer index {} for channel {}, disabling effect",
+                        params->outputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+    }
+
     mix_id = in_params.mix_id;
     process_order = in_params.process_order;
-    enabled = in_params.enabled;
+    // Disable effect if parameters are corrupted to prevent audio issues
+    enabled = in_params.enabled && parameters_valid;
 
     error_info.error_code = ResultSuccess;
     error_info.address = CpuAddr(0);
@@ -25,9 +62,48 @@ void BiquadFilterInfo::Update(BehaviorInfo::ErrorInfo& error_info,
     auto params{reinterpret_cast<ParameterVersion2*>(parameter.data())};
 
     std::memcpy(params, in_specific, sizeof(ParameterVersion2));
+
+    // Check for corrupted parameters - if detected, disable the effect to prevent audio issues
+    bool parameters_valid = true;
+
+    // Validate channel_count
+    if (params->channel_count < 0 || static_cast<u32>(params->channel_count) > MaxChannels) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid channel_count {}, disabling effect",
+                    params->channel_count);
+        parameters_valid = false;
+    }
+
+    // Validate input/output buffer indices only for active channels
+    const s8 active_channels = parameters_valid ? params->channel_count : 0;
+    for (s8 i = 0; static_cast<u32>(i) < MaxChannels && i < active_channels && parameters_valid; i++) {
+        // Negative values are allowed (indicate unused channels), but check for out-of-range values
+        if (params->inputs[i] < -1 || params->inputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid input buffer index {} for channel {}, disabling effect",
+                        params->inputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+        if (params->outputs[i] < -1 || params->outputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid output buffer index {} for channel {}, disabling effect",
+                        params->outputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+    }
+
+    // Validate parameter state
+    if (static_cast<u8>(params->state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid parameter state {}, disabling effect",
+                    static_cast<u8>(params->state));
+        parameters_valid = false;
+    }
+
     mix_id = in_params.mix_id;
     process_order = in_params.process_order;
-    enabled = in_params.enabled;
+    // ParameterVersion2 uses state field similar to v1
+    // Effect is enabled if in_params.enabled, parameters are valid, and state is within valid range
+    enabled = in_params.enabled && parameters_valid &&
+              static_cast<u8>(params->state) <= static_cast<u8>(EffectInfoBase::ParameterState::Updated);
 
     error_info.error_code = ResultSuccess;
     error_info.address = CpuAddr(0);

src/audio_core/sink/sink_stream.cpp

@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <algorithm>
 #include <array>
 #include <atomic>
 #include <memory>
@@ -229,10 +230,19 @@ void SinkStream::ProcessAudioOutAndRender(std::span<s16> output_buffer, std::siz
         // If the playing buffer has been consumed or has no frames, we need a new one
         if (playing_buffer.consumed || playing_buffer.frames == 0) {
             if (!queue.try_dequeue(playing_buffer)) {
-                // If no buffer was available we've underrun, fill the remaining buffer with
+                // If no buffer was available we've underrun, repeat the last frame to maintain
-                // the last written frame and continue.
+                // audio continuity. Use the last valid frame we played to avoid harsh transitions.
-                for (size_t i = frames_written; i < num_frames; i++) {
+                if (frames_written > 0) {
-                    std::memcpy(&output_buffer[i * frame_size], &last_frame[0], frame_size_bytes);
+                    // We have a valid last_frame, repeat it smoothly
+                    for (size_t i = frames_written; i < num_frames; i++) {
+                        std::memcpy(&output_buffer[i * frame_size], &last_frame[0], frame_size_bytes);
+                    }
+                } else {
+                    // No frames written yet, fill with silence
+                    static constexpr std::array<s16, 6> silence{};
+                    for (size_t i = frames_written; i < num_frames; i++) {
+                        std::memcpy(&output_buffer[i * frame_size], &silence[0], frame_size_bytes);
+                    }
                 }
                 frames_written = num_frames;
                 continue;