ngs2: apply mastering voice full band and LFE gain

Co-authored-by: Phr3d13 <phr3d13@gmail.com>

src/libs/ngs2.cpp

@@ -568,6 +568,8 @@ struct Ngs2VoiceInternal {
 	std::vector<float>              output_matrix;
 	uint32_t                        channels        = 0;
 	uint32_t                        output_id       = 0;
+	float                           fbw_level       = 1.0f;
+	float                           lfe_level       = 1.0f;
 	bool                            rendering       = false;
 	bool                            rendered        = false;
 	bool                            has_samples     = false;
@@ -1978,10 +1980,13 @@ int KYTY_SYSV_ABI Ngs2SystemRender(uintptr_t system_handle, const Ngs2RenderBuff
 			pcm = static_cast<float*>(output.buffer);
 		}
 		for (uint32_t dst = 0; dst < output.num_channels; ++dst) {
+			// Output channel 3 is LFE; every other channel is full band.
+			const float gain = dst == 3 ? voice->lfe_level : voice->fbw_level;
 			for (uint32_t src = 0; src < voice->channels; ++src) {
-				const float level = voice->output_matrix.empty()
+				const float level =
-				                        ? (src == dst ? 1.0f : 0.0f)
+				    gain * (voice->output_matrix.empty()
-				                        : voice->output_matrix.at(src * output.num_channels + dst);
+				                ? static_cast<float>(src == dst)
+				                : voice->output_matrix.at(src * output.num_channels + dst));
 				if (level == 0.0f) {
 					continue;
 				}
@@ -2481,6 +2486,12 @@ int KYTY_SYSV_ABI Ngs2VoiceControl(uintptr_t voice_handle, const Ngs2VoiceParamH
 						                            matrix->levels + matrix->num_levels);
 						break;
 					}
+					case 4: {
+						const auto* levels = reinterpret_cast<const float*>(values);
+						voice->fbw_level   = std::clamp(levels[0], 0.0f, 4.0f);
+						voice->lfe_level   = std::clamp(levels[1], 0.0f, 4.0f);
+						break;
+					}
 					case 5: voice->output_id = values[0]; break;
 					default: EXIT("unsupported mastering control: 0x%08" PRIx32 "\n", param->id);
 				}

tests/Ngs2SamplerTests.cpp

@@ -822,6 +822,38 @@ void TestPatchToRackHandle() {
 	      "patch to a rack handle did not connect to its voice #0");
 }
 
+void TestMasteringGain() {
+	Ngs2Internal system;
+	system.option                   = Ngs2DefaultSystemOption();
+	system.option.num_grain_samples = 1;
+	Ngs2RackOptionUnion sampler_option {}, mastering_option {};
+	Ngs2FillDefaultRackOption(0x1000, &sampler_option);
+	Ngs2FillDefaultRackOption(0x3000, &mastering_option);
+	sampler_option.common.max_voices = 1;
+	RenderRack sampler(system, 0x1000, sampler_option.common);
+	RenderRack master(system, 0x3000, mastering_option.common);
+	auto& source = sampler.Voice();
+	auto& mastering = master.Voice();
+	mastering.channels = 8;
+	mastering.state = Ngs2VoicePlayState::Playing;
+	const int16_t frame[8] = {8192, 8192, 8192, 8192, 8192, 8192, 8192, 8192};
+	source.SetupSampler({0x12, 8, 48000});
+	source.blocks.push_back({reinterpret_cast<const uint8_t*>(frame), {0, sizeof(frame), 0, 0, 1}});
+	source.ports[0].dest = &mastering;
+	source.SetEvent(1);
+	struct {
+		Ngs2VoiceParamHeader header {16, 0, 0x30000004};
+		float fbw = 5.0f, lfe = 0.5f;
+	} gain;
+	float pcm[8] = {};
+	Ngs2RenderBufferInfo output {pcm, sizeof(pcm), 0x18, 8};
+	const float expected[8] = {1.0f, 1.0f, 1.0f, 0.125f, 1.0f, 1.0f, 1.0f, 1.0f};
+	Check(Ngs2VoiceControl(reinterpret_cast<uintptr_t>(&mastering), &gain.header) == OK &&
+	          Ngs2SystemRender(reinterpret_cast<uintptr_t>(&system), &output, 1) == OK &&
+	          std::ranges::equal(pcm, expected),
+	      "mastering gain was not clamped or applied per full band and LFE channel");
+}
+
 void TestCustomMasteringChannelMixer() {
 	Ngs2Internal system;
 	system.option = Ngs2DefaultSystemOption();
@@ -1819,6 +1851,7 @@ int main() {
 	TestAtrac9Discrete();
 	TestPcm16RenderOutput();
 	TestPatchToRackHandle();
+	TestMasteringGain();
 	TestCustomMasteringChannelMixer();
 	TestCustomVoiceStateCapacity();
 	TestSubmixerSetupAndRouting();