BackLeft

BackLeft

#Overview

name: BackLeft

The value of this variable can be defined or overridden in .ini config files. 2 .ini config files referencing this setting variable.

It is referenced in 47 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of BackLeft is to represent the back-left audio channel in a surround sound setup. This variable is part of the audio channel configuration system in Unreal Engine 5, specifically within the EAudioMixerChannel enumeration.

BackLeft is used across various Unreal Engine subsystems and modules related to audio processing, rendering, and mixing. Based on the provided code references, it’s utilized in:

  1. Audio Mixer subsystem
  2. Sound Field Rendering module
  3. Signal Processing module
  4. Audio Synesthesia plugin
  5. Synthesis plugin
  6. Media Utils module
  7. XAudio2 platform-specific implementation

The value of this variable is typically set when initializing audio devices or configuring audio channel layouts. It’s often used in conjunction with other channel types like FrontLeft, FrontRight, BackRight, etc., to define the spatial arrangement of audio outputs.

BackLeft frequently interacts with other channel variables, especially in channel mapping and audio mixing operations. It’s often paired with BackRight for rear surround sound effects.

Developers should be aware that:

  1. The exact behavior of BackLeft may depend on the audio hardware and drivers being used.
  2. Not all audio setups will have a BackLeft channel (e.g., stereo or 5.1 systems).
  3. The ordering of channels can be platform-specific or device-specific.

Best practices when using this variable include:

  1. Always check the available channel configuration before assuming BackLeft is present.
  2. Use the appropriate channel mapping functions provided by the engine when working with multi-channel audio.
  3. Consider fallback options for audio systems that don’t support BackLeft (e.g., mixing into side or front channels).
  4. Be mindful of the differences in channel ordering across different platforms and audio APIs.

#Setting Variables

#References In INI files

Location: <Workspace>/Engine/Config/BaseEngine.ini:1575, section: [AudioChannelAzimuthMap]

Location: <Workspace>/Engine/Config/BaseEngine.ini:1591, section: [AudioDefaultChannelOrder]

#References in C++ code

#Callsites

This variable is referenced in the following C++ source code:

#Loc: <Workspace>/Engine/Plugins/Experimental/Avalanche/Source/AvalancheShapes/Private/DynamicMeshes/AvaShapeCubeDynMesh.cpp:395

Scope (from outer to inner):

file
function     bool UAvaShapeCubeDynamicMesh::GenerateBackMeshSections

Source code excerpt:

	static const FVector BackNormal(1, 0, 0);
	const FVector BackLeftLoc(SegmentSize.X, -(SegmentSize.Y - BevelSize.Y), (SegmentSize.Z - BevelSize.Z));
	const FAvaShapeCachedVertex3D BackLeft = CacheVertexCreate(BackMesh, BackLeftLoc * Scale, BackNormal);
	const FVector BackRightLoc(SegmentSize.X, (SegmentSize.Y - BevelSize.Y), -(SegmentSize.Z - BevelSize.Z));
	const FAvaShapeCachedVertex3D BackRight = CacheVertexCreate(BackMesh, BackRightLoc * Scale, BackNormal);

	AddVertex(BackMesh, BackLeft);
	const FVector BackLeftLoc2(SegmentSize.X, (SegmentSize.Y - BevelSize.Y), (SegmentSize.Z - BevelSize.Z));
	int32 BackLeftIdx = AddVertexRaw(BackMesh, BackLeftLoc2 * Scale, BackNormal);
	AddVertex(BackMesh, BackRight);

	AddVertex(BackMesh, BackRight);
	const FVector BackRightLoc2(SegmentSize.X, -(SegmentSize.Y - BevelSize.Y), -(SegmentSize.Z - BevelSize.Z));
	int32 BackRightIdx = AddVertexRaw(BackMesh, BackRightLoc2 * Scale, BackNormal);
	AddVertex(BackMesh, BackLeft);

	if (BevelSizeRatio > 0)
	{
		CreateBevelCorner(BackMesh, BackLeftLoc2, BackLeftLoc, BackNormal, BackLeftIdx, BackLeft.Index,
			BevelSize, Scale, FVector(SegmentSize.X, SegmentSize.Y, SegmentSize.Z), FVector(SegmentSize.X, -SegmentSize.Y, SegmentSize.Z));

		CreateBevelCorner(BackMesh, BackLeftLoc, BackRightLoc2, BackNormal, BackLeft.Index, BackRightIdx,
			BevelSize, Scale, FVector(SegmentSize.X, -SegmentSize.Y, SegmentSize.Z), FVector(SegmentSize.X, -SegmentSize.Y, -SegmentSize.Z));

		CreateBevelCorner(BackMesh, BackRightLoc2, BackRightLoc, BackNormal, BackRightIdx, BackRight.Index,
			BevelSize, Scale, FVector(SegmentSize.X, -SegmentSize.Y, -SegmentSize.Z), FVector(SegmentSize.X, SegmentSize.Y, -SegmentSize.Z));

		CreateBevelCorner(BackMesh, BackRightLoc, BackLeftLoc2, BackNormal, BackRight.Index, BackLeftIdx,

#Loc: <Workspace>/Engine/Plugins/Experimental/Water/Source/Runtime/Private/WaterBodyRiverComponent.cpp:252

Scope (from outer to inner):

file
function     static void AddTerminalVerticesForRiverSpline

Source code excerpt:

	}

	const FVertexInfo BackLeft(FVector3d(Pos - OutwardDistance + TangentialOffset - DilationOffset));
	const FVertexInfo Left(FVector3d(Pos - OutwardDistance + TangentialOffset));
	const FVertexInfo Right(FVector3d(Pos + OutwardDistance + TangentialOffset));
	const FVertexInfo BackRight(FVector3d(Pos + OutwardDistance + TangentialOffset + DilationOffset));

	const int32 BaseIndex = OutDilatedMesh.GetVerticesBuffer().Num();

	OutDilatedMesh.AppendVertex(BackLeft);
	OutDilatedMesh.AppendVertex(Left);
	OutDilatedMesh.AppendVertex(Right);
	OutDilatedMesh.AppendVertex(BackRight);


	if (Edge == ERiverBoundaryEdge::End)

#Loc: <Workspace>/Engine/Plugins/Runtime/AudioSynesthesia/Source/AudioSynesthesiaCore/Private/LoudnessAnalyzer.cpp:222

Scope (from outer to inner):

file
namespace    Audio
function     FMultichannelLoudnessAnalyzer::FMultichannelLoudnessAnalyzer

Source code excerpt:


        // If elevation angle is less than 30 degrees and azimuth is between 60 and 120, set channel weight to 1.5f. 
        ChannelWeights[EAudioMixerChannel::BackLeft] = 1.5f;
        ChannelWeights[EAudioMixerChannel::BackRight] = 1.5f;

        MonoBuffer.Reset(InSettings.FFTSize);
        MonoBuffer.AddUninitialized(InSettings.FFTSize);
    }

#Loc: <Workspace>/Engine/Plugins/Runtime/Synthesis/Source/Synthesis/Private/ConvolutionReverb.cpp:59

Scope (from outer to inner):

file
namespace    Audio
namespace    ConvolutionReverbIntrinsics

Source code excerpt:

				EAudioMixerChannel::Type::FrontRight,
				EAudioMixerChannel::Type::FrontCenter,
				EAudioMixerChannel::Type::BackLeft,
				EAudioMixerChannel::Type::BackRight,
				EAudioMixerChannel::Type::SideLeft,
				EAudioMixerChannel::Type::SideRight
			},

			// Eight channels (7.1)

#Loc: <Workspace>/Engine/Plugins/Runtime/Synthesis/Source/Synthesis/Private/ConvolutionReverb.cpp:71

Scope (from outer to inner):

file
namespace    Audio
namespace    ConvolutionReverbIntrinsics

Source code excerpt:

				EAudioMixerChannel::Type::FrontCenter,
				EAudioMixerChannel::Type::LowFrequency,
				EAudioMixerChannel::Type::BackLeft,
				EAudioMixerChannel::Type::BackRight,
				EAudioMixerChannel::Type::SideLeft,
				EAudioMixerChannel::Type::SideRight
			}
		};

#Loc: <Workspace>/Engine/Plugins/Runtime/Synthesis/Source/Synthesis/Private/SubmixChannelFormatConverter.cpp:27

Scope (from outer to inner):

file
namespace    Audio
namespace    SubmixChannelFormatConverterPrivate

Source code excerpt:

		static const TMap<EAudioMixerChannel::Type, TArray<EAudioMixerChannel::Type>> PairedRearChannelTypes =
		{
			{ EAudioMixerChannel::FrontLeft, { EAudioMixerChannel::BackLeft, EAudioMixerChannel::SideLeft, EAudioMixerChannel::TopBackLeft } },
			{ EAudioMixerChannel::FrontRight, { EAudioMixerChannel::BackRight, EAudioMixerChannel::SideRight, EAudioMixerChannel::TopBackRight } },
			{ EAudioMixerChannel::FrontCenter, { EAudioMixerChannel::BackCenter, EAudioMixerChannel::TopCenter, EAudioMixerChannel::TopBackCenter } },
			{ EAudioMixerChannel::FrontLeftOfCenter, { EAudioMixerChannel::BackLeft, EAudioMixerChannel::SideLeft, EAudioMixerChannel::TopBackLeft } },
			{ EAudioMixerChannel::FrontRightOfCenter, { EAudioMixerChannel::BackRight, EAudioMixerChannel::SideRight, EAudioMixerChannel::TopBackRight } },
			{ EAudioMixerChannel::TopFrontLeft, { EAudioMixerChannel::BackLeft, EAudioMixerChannel::SideLeft, EAudioMixerChannel::TopBackLeft } },
			{ EAudioMixerChannel::TopFrontRight, { EAudioMixerChannel::BackRight, EAudioMixerChannel::SideRight, EAudioMixerChannel::TopBackRight } },
			{ EAudioMixerChannel::TopFrontCenter, { EAudioMixerChannel::BackCenter, EAudioMixerChannel::TopCenter, EAudioMixerChannel::TopBackCenter } }
		};

		// For a _flipped_ rear-channel-bleed, this map pairs all front channels with all
		// associated rear channels that should receive bled audio.

#Loc: <Workspace>/Engine/Plugins/Runtime/Synthesis/Source/Synthesis/Private/SubmixChannelFormatConverter.cpp:111

Scope (from outer to inner):

file
namespace    Audio
function     bool GetSubmixChannelOrderForNumChannels

Source code excerpt:

						EAudioMixerChannel::Type::FrontCenter,
						EAudioMixerChannel::Type::LowFrequency,
						EAudioMixerChannel::Type::BackLeft,
						EAudioMixerChannel::Type::BackRight,
						EAudioMixerChannel::Type::SideLeft,
						EAudioMixerChannel::Type::SideRight
					}
				);

#Loc: <Workspace>/Engine/Plugins/Runtime/Synthesis/Source/Synthesis/Private/SubmixChannelFormatConverter.cpp:384

Scope (from outer to inner):

file
namespace    Audio
function     bool FSimpleUpmixer::GetSimpleUpmixerStaticMixEntries

Source code excerpt:

		const int32 InputSideLeftIndex = InInputChannelTypes.Find(EAudioMixerChannel::Type::SideLeft);
		const int32 InputSideRightIndex = InInputChannelTypes.Find(EAudioMixerChannel::Type::SideRight);
		const int32 InputBackLeftIndex = InInputChannelTypes.Find(EAudioMixerChannel::Type::BackLeft);
		const int32 InputBackRightIndex = InInputChannelTypes.Find(EAudioMixerChannel::Type::BackRight);

		// Query which output channels exist
		const int32 OutputFrontLeftIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::FrontLeft);
		const int32 OutputFrontRightIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::FrontRight);
		const int32 OutputSideLeftIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::SideLeft);
		const int32 OutputSideRightIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::SideRight);
		const int32 OutputBackLeftIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::BackLeft);
		const int32 OutputBackRightIndex = InOutputChannelTypes.Find(EAudioMixerChannel::Type::BackRight);

		// Check for mono input and stereo output.
		const bool bInputIsMono = (1 == InInputChannelTypes.Num()) && (InInputChannelTypes[0] == EAudioMixerChannel::Type::FrontCenter); 
		const bool bOutputHasFrontLeft = (INDEX_NONE != OutputFrontLeftIndex);
		const bool bOutputHasFrontRight = (INDEX_NONE != OutputFrontRightIndex);

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Private/AudioMixerChannelMaps.cpp:46

Scope (from outer to inner):

file
namespace    Audio

Source code excerpt:

			EAudioMixerChannel::FrontCenter,
			EAudioMixerChannel::LowFrequency,
			EAudioMixerChannel::BackLeft,
			EAudioMixerChannel::BackRight,
			EAudioMixerChannel::SideLeft,
			EAudioMixerChannel::SideRight
		},

		// ESubmixChannelFormat::Ambisonics

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Private/AudioMixerChannelMaps.cpp:61

Scope (from outer to inner):

file
namespace    Audio

Source code excerpt:

			EAudioMixerChannel::FrontCenter,
			EAudioMixerChannel::LowFrequency,
			EAudioMixerChannel::BackLeft,
			EAudioMixerChannel::BackRight,
			EAudioMixerChannel::SideLeft,
			EAudioMixerChannel::SideRight
		}, 
	};

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Private/AudioMixerChannelMaps.cpp:235

Scope (from outer to inner):

file
namespace    Audio
function     void FMixerDevice::InitializeChannelAzimuthMap

Source code excerpt:

		DefaultChannelAzimuthPositions[EAudioMixerChannel::LowFrequency] = { EAudioMixerChannel::LowFrequency, INDEX_NONE };

		DefaultChannelAzimuthPositions[EAudioMixerChannel::BackLeft] = { EAudioMixerChannel::BackLeft, 210 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::BackRight] = { EAudioMixerChannel::BackRight, 150 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::FrontLeftOfCenter] = { EAudioMixerChannel::FrontLeftOfCenter, 15 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::FrontRightOfCenter] = { EAudioMixerChannel::FrontRightOfCenter, 345 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::BackCenter] = { EAudioMixerChannel::BackCenter, 180 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::SideLeft] = { EAudioMixerChannel::SideLeft, 250 };
		DefaultChannelAzimuthPositions[EAudioMixerChannel::SideRight] = { EAudioMixerChannel::SideRight, 110 };

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Private/AudioMixerDevice.cpp:459

Scope (from outer to inner):

file
namespace    Audio
function     TArray<Audio::FChannelPositionInfo>* FMixerDevice::GetDefaultPositionMap

Source code excerpt:

														,SpeakerPositions[EAudioMixerChannel::FrontCenter] //center
														,SpeakerPositions[EAudioMixerChannel::LowFrequency] //LFE
														,SpeakerPositions[EAudioMixerChannel::BackLeft] // Left Rear
														,SpeakerPositions[EAudioMixerChannel::BackRight] // Right Rear
														,SpeakerPositions[EAudioMixerChannel::SideLeft] // Left Surround
														,SpeakerPositions[EAudioMixerChannel::SideRight] // Right Surround
				};

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Private/AudioMixerSource.cpp:2198

Scope (from outer to inner):

file
lambda-function

Source code excerpt:

							TMap<EAudioMixerChannel::Type, float> LeftOmniMap;
							LeftOmniMap.Add(EAudioMixerChannel::FrontLeft, 1.0f);
							LeftOmniMap.Add(EAudioMixerChannel::BackLeft, 1.0f);

							return LeftOmniMap;
						};

						auto CreateRightOmniMap = []() -> TMap<EAudioMixerChannel::Type, float>
						{

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Public/AudioMixerBlueprintLibrary.h:61

Scope: file

Source code excerpt:

	FrontCenter,
	LowFrequency,
	BackLeft,
	BackRight,
	FrontLeftOfCenter,
	FrontRightOfCenter,
	BackCenter,
	SideLeft,
	SideRight,

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixer/Public/AudioMixerBlueprintLibrary.h:88

Scope (from outer to inner):

file
function     inline const TCHAR* ToString

Source code excerpt:

		case EAudioMixerChannelType::FrontCenter:			return TEXT("FrontCenter");
		case EAudioMixerChannelType::LowFrequency:			return TEXT("LowFrequency");
		case EAudioMixerChannelType::BackLeft:				return TEXT("BackLeft");
		case EAudioMixerChannelType::BackRight:				return TEXT("BackRight");
		case EAudioMixerChannelType::FrontLeftOfCenter:		return TEXT("FrontLeftOfCenter");
		case EAudioMixerChannelType::FrontRightOfCenter:	return TEXT("FrontRightOfCenter");
		case EAudioMixerChannelType::BackCenter:			return TEXT("BackCenter");
		case EAudioMixerChannelType::SideLeft:				return TEXT("SideLeft");
		case EAudioMixerChannelType::SideRight:				return TEXT("SideRight");

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixerCore/Private/AudioMixer.cpp:815

Scope (from outer to inner):

file
namespace    Audio
function     static void InitializeDefaultChannelOrder

Source code excerpt:

		DefaultChannelOrder[4] = EAudioMixerChannel::SideLeft;
		DefaultChannelOrder[5] = EAudioMixerChannel::SideRight;
		DefaultChannelOrder[6] = EAudioMixerChannel::BackLeft;
		DefaultChannelOrder[7] = EAudioMixerChannel::BackRight;

		bool bOverridden = false;
		EAudioMixerChannel::Type ChannelMapOverride[AUDIO_MIXER_MAX_OUTPUT_CHANNELS];
		for (int32 i = 0; i < AUDIO_MIXER_MAX_OUTPUT_CHANNELS; ++i)
		{

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixerCore/Public/AudioMixer.h:83

Scope (from outer to inner):

file
namespace    EAudioMixerChannel

Source code excerpt:

		FrontCenter,
		LowFrequency,
		BackLeft,
		BackRight,
		FrontLeftOfCenter,
		FrontRightOfCenter,
		BackCenter,
		SideLeft,
		SideRight,

#Loc: <Workspace>/Engine/Source/Runtime/AudioMixerCore/Public/AudioMixer.h:112

Scope (from outer to inner):

file
namespace    EAudioMixerChannel
function     inline const TCHAR* ToString

Source code excerpt:

		case FrontCenter:			return TEXT("FrontCenter");
		case LowFrequency:			return TEXT("LowFrequency");
		case BackLeft:				return TEXT("BackLeft");
		case BackRight:				return TEXT("BackRight");
		case FrontLeftOfCenter:		return TEXT("FrontLeftOfCenter");
		case FrontRightOfCenter:	return TEXT("FrontRightOfCenter");
		case BackCenter:			return TEXT("BackCenter");
		case SideLeft:				return TEXT("SideLeft");
		case SideRight:				return TEXT("SideRight");

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:48

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:


	static const float Matrix_7_1[] = {
		// FrontLeft	FrontRight	BackLeft	LFE			BackRight	SideLeft	SideRight
		0.707f,			0.707f,		0.5f,		0.0f,		0.5f,		0.5f,		0.5f,		// Mono
	};

	static const float Matrix_8_1[] = {
		// FrontLeft	FrontRight	Center		LowFreq		SideLeft	SideRight	BackLeft	BackRight
		0.707f,			0.707f,		1.0f,		0.0f,		0.5f,		0.5f,		0.5f,		0.5f,		// Mono
	};

	static const float* ToMono[8] = {
		Matrix_1_1,
		Matrix_2_1,

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:107

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:


	static const float Matrix_7_2[] = {
		// FrontLeft	FrontRight	BackLeft	LFE			BackRight	SideLeft	SideRight
		1.0f,			0.0f,		0.707f,		0.0f,		0.0f,		0.707f,		0.0f,		// Left
		0.0f,			1.0f,		0.0f,		0.0f,		0.707f,		0.0f,		0.707f,		// Right
	};

	static const float Matrix_8_2[] = {
		// FrontLeft	FrontRight	Center		LowFreq		SideLeft	SideRight	BackLeft	BackRight
		1.0f,			0.0f,		0.707f,		0.0f,		0.707f,		0.0f,		0.707f,		0.0f,		// Left
		0.0f,			1.0f,		0.707f,		0.0f,		0.0f,		0.707f,		0.0f,		0.707f,		// Right
	};

	static const float* ToStereo[8] = {
		Matrix_1_2,

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:140

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,		// SideLeft
		0.0f,		// SideRight
		0.0f,		// BackLeft
		0.0f,		// BackRight
	};

	static const float Matrix_2_8[] = {
		// FrontLeft	FrontRight
		1.0f,			0.0f,			// FrontLeft

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:152

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,			0.0f,			// SideLeft
		0.0f,			0.0f,			// SideRight
		0.0f,			0.0f,			// BackLeft
		0.0f,			0.0f,			// BackRight
	};

	static const float Matrix_3_8[] = {
		// FrontLeft	FrontRight	Center
		1.0f,			0.0f,		0.0f,	// FrontLeft

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:164

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,			0.0f,		0.0f,	// SideLeft
		0.0f,			0.0f,		0.0f,	// SideRight
		0.0f,			0.0f,		0.0f,	// BackLeft
		0.0f,			0.0f,		0.0f,	// BackRight
	};

	static const float Matrix_4_8[] = {
		// FrontLeft	FrontRight	SideLeft	SideRight
		1.0f,			0.0f,		0.0f,		0.0f,		// FrontLeft

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:176

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,			0.0f,		1.0f,		0.0f,		// SideLeft
		0.0f,			0.0f,		0.0f,		1.0f,		// SideRight
		0.0f,			0.0f,		0.0f,		0.0f,		// BackLeft
		0.0f,			0.0f,		0.0f,		0.0f,		// BackRight
	};

	static const float Matrix_5_8[] = {
		// FrontLeft	FrontRight	Center		SideLeft	SideRight
		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:188

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		// SideRight
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// BackLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// BackRight
	};

	static const float Matrix_6_8[] = {
		// FrontLeft	FrontRight	Center		LowFreq		SideLeft	SideRight
		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft

#Loc: <Workspace>/Engine/Source/Runtime/MediaUtils/Private/MediaAudioResampler.cpp:200

Scope (from outer to inner):

file
namespace    MediaAudioResampler

Source code excerpt:

		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		// SideRight
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// BackLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// BackRight
	};

	static const float Matrix_7_8[] = {
		// FrontLeft	FrontRight	BackLeft	LFE			BackRight	SideLeft	SideRight
		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
		0.0f,			1.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// Center
		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		0.0f,		0.0f,		// LowFrequency
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		// SideRight
		0.0f,			0.0f,		1.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// BackLeft
		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		0.0f,		// BackRight
	};

	static const float Matrix_8_8[] = {
		// FrontLeft	FrontRight	Center		LowFreq		SideLeft	SideRight	BackLeft	BackRight
		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
		0.0f,			1.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
		0.0f,			0.0f,		1.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// Center
		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		0.0f,		0.0f,		0.0f,		// LowFrequency
		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		0.0f,		0.0f,		// SideLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		0.0f,		// SideRight
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		0.0f,		// BackLeft
		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		0.0f,		1.0f,		// BackRight
	};

	static const float* ToSurround[8] = {
		Matrix_1_8,
		Matrix_2_8,

#Loc: <Workspace>/Engine/Source/Runtime/NonRealtimeAudioRenderer/Private/AudioMixerPlatformNonRealtime.cpp:168

Scope (from outer to inner):

file
namespace    Audio
function     bool FMixerPlatformNonRealtime::GetOutputDeviceInfo

Source code excerpt:

		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::FrontCenter);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::LowFrequency);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::BackLeft);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::BackRight);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::SideLeft);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::SideRight);

		return true;
	}

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:12

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float ToMonoMatrix[ChannelMapMaxNumChannels * 1] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight  
			0.707f,			0.707f,		1.0f,		0.0f,			0.5f,		0.5f,		0.5f,		0.5f,		// FrontLeft
		};

		static constexpr float VorbisToMonoMatrix[ChannelMapVorbisNumChannels * 1] =
		{
			// FrontLeft	Center		FrontRight	SideLeft		SideRight	LowFrequency

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:24

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float ToStereoMatrix[ChannelMapMaxNumChannels * 2] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight  
			1.0f,			0.0f,		0.707f,		0.0f,			0.707f,		0.0f,		0.707f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.707f,		0.0f,			0.0f,		0.707f,		0.0f,		0.707f,		// FrontRight
		};

		static constexpr float VorbisToStereoMatrix[ChannelMapVorbisNumChannels * 2] =
		{

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:38

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float ToTriMatrix[ChannelMapMaxNumChannels * 3] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight  
			1.0f,			0.0f,		0.0f,		0.0f,			0.707f,		0.0f,		0.707f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.0f,		0.0f,			0.0f,		0.707f,		0.0f,		0.707f,		// FrontRight
			0.0f,			0.0f,		1.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// Center
		};

		static constexpr float VorbisToTriMatrix[ChannelMapVorbisNumChannels * 3] =

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:54

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float ToQuadMatrix[ChannelMapMaxNumChannels * 4] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight	
			1.0f,			0.0f,		0.707f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.707f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		1.0f,		// SideRight
		};

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:72

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float To5Matrix[ChannelMapMaxNumChannels * 5] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight	
			1.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		1.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// Center
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		1.0f,		// SideRight
		};

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:92

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float To5Point1Matrix[ChannelMapMaxNumChannels * 6] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight	
			1.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		1.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// Center
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// LowFrequency
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		1.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		1.0f,		// SideRight

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:114

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float ToHexMatrix[ChannelMapMaxNumChannels * 7] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight	
			1.0f,			0.0f,		0.707f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.707f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		// BackLeft
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// LFE
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		// BackRight
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		0.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		0.0f,		// SideRight
		};

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:129

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

			1.0f,			0.707f,		0.0f,		0.0f,			0.0f,		0.0f,		// FrontLeft
			0.0f,			0.707f,		1.0f,		0.0f,			0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		// BackLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		// LFE
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		// BackRight
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		// SideRight
		};

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:140

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

		static constexpr float To7Point1Matrix[ChannelMapMaxNumChannels * 8] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight
			1.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		1.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontCenter
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// LowFrequency
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		0.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		0.0f,		// SideRight
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		// BackLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		// BackRight
		};

#else //PLATFORM_MICROSOFT

		// NOTE: the BackLeft/BackRight and SideLeft/SideRight are reversed than they should be since our 7.1 importer code has it backward
		static constexpr float To7Point1Matrix[ChannelMapMaxNumChannels * 8] =
		{
			// FrontLeft	FrontRight	Center		LowFrequency	SideLeft	SideRight	BackLeft	BackRight
			1.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontLeft
			0.0f,			1.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontRight
			0.0f,			0.0f,		1.0f,		0.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// FrontCenter
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		0.0f,		0.0f,		// LowFrequency
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		1.0f,		0.0f,		// BackLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		0.0f,		1.0f,		// BackRight
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		0.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		1.0f,		0.0f,		0.0f,		// SideRight
		};

#endif//PLATFORM_MICROSOFT

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ChannelMap.cpp:178

Scope (from outer to inner):

file
namespace    Audio
namespace    ChannelMapPrivate

Source code excerpt:

			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		// SideLeft
			0.0f,			0.0f,		0.0f,		0.0f,			0.0f,		0.0f,		// SideRight
			0.0f,			0.0f,		0.0f,		1.0f,			0.0f,		0.0f,		// BackLeft
			0.0f,			0.0f,		0.0f,		0.0f,			1.0f,		0.0f,		// BackRight
		};

		static float const * const OutputChannelMaps[ChannelMapMaxNumChannels] =
		{
			ToMonoMatrix,

#Loc: <Workspace>/Engine/Source/Runtime/SignalProcessing/Private/ReverbFast.cpp:235

Scope (from outer to inner):

file
namespace    Audio
function     void FPlateReverbFast::InterleaveAndMixOutput

Source code excerpt:

					OutSampleData[OutPos + EAudioMixerChannel::FrontLeft] = FrontLeftSampleData[i];
					OutSampleData[OutPos + EAudioMixerChannel::FrontRight] = FrontRightSampleData[i];
					OutSampleData[OutPos + EAudioMixerChannel::BackLeft] = BackLeftSampleData[i];
					OutSampleData[OutPos + EAudioMixerChannel::BackRight] = BackRightSampleData[i];
				}
			}
		}
	}

#Loc: <Workspace>/Engine/Source/Runtime/SoundFieldRendering/Private/SoundFieldRendering.cpp:55

Scope (from outer to inner):

file
function     FSoundFieldDecoder::FSoundFieldDecoder

Source code excerpt:

	constexpr const int32 FrontRightOffset  = NumAmbiChannels * EAudioMixerChannel::FrontRight;
	constexpr const int32 FrontCenterOffset = NumAmbiChannels * EAudioMixerChannel::FrontCenter;
	constexpr const int32 BackLeftOffest    = NumAmbiChannels * EAudioMixerChannel::BackLeft;
	constexpr const int32 BackRightOffset   = NumAmbiChannels * EAudioMixerChannel::BackRight;
	constexpr const int32 BackCenterOffset  = NumAmbiChannels * EAudioMixerChannel::BackCenter;

	VectorRegister FrontLeftGains   = VectorLoadAligned(SpeakerGainsPtr);
	VectorRegister FrontRightGains  = VectorLoadAligned(SpeakerGainsPtr + FrontRightOffset);
	VectorRegister FrontCenterGains = VectorLoadAligned(SpeakerGainsPtr + FrontCenterOffset);

#Loc: <Workspace>/Engine/Source/Runtime/SoundFieldRendering/Private/SoundFieldRendering.cpp:688

Scope: file

Source code excerpt:

	,{EAudioMixerChannel::FrontCenter, 0, 0}
	,{EAudioMixerChannel::LowFrequency, -1, 0}
	,{EAudioMixerChannel::BackLeft, 210, 0} 
	,{EAudioMixerChannel::BackRight, 150, 0}
	,{EAudioMixerChannel::SideLeft, 250, 0}
	,{EAudioMixerChannel::SideRight, 110, 0}
	,{EAudioMixerChannel::BackCenter, 180,0}
};

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/AudioMixerPlatformXAudio2.cpp:860

Scope (from outer to inner):

file
namespace    Audio
function     static bool GetMMDeviceInfo

Source code excerpt:

					EAudioMixerChannel::SideLeft,
					EAudioMixerChannel::SideRight,
					EAudioMixerChannel::BackLeft,
					EAudioMixerChannel::BackRight,
				};

				EAudioMixerChannel::Type* ChannelOrdering = DefaultChannelOrdering;

				// Override channel ordering for some special cases

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/AudioMixerPlatformXAudio2.cpp:872

Scope (from outer to inner):

file
namespace    Audio
function     static bool GetMMDeviceInfo

Source code excerpt:

						EAudioMixerChannel::FrontLeft,
						EAudioMixerChannel::FrontRight,
						EAudioMixerChannel::BackLeft,
						EAudioMixerChannel::BackRight,
					};

					ChannelOrdering = DefaultChannelOrderingQuad;
				}
				else if (OutInfo.NumChannels == 6)

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/AudioMixerPlatformXAudio2.cpp:885

Scope (from outer to inner):

file
namespace    Audio
function     static bool GetMMDeviceInfo

Source code excerpt:

						EAudioMixerChannel::FrontCenter,
						EAudioMixerChannel::LowFrequency,
						EAudioMixerChannel::BackLeft,
						EAudioMixerChannel::BackRight,
					};

					ChannelOrdering = DefaultChannelOrdering51;
				}

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/AudioMixerPlatformXAudio2.cpp:1036

Scope (from outer to inner):

file
namespace    Audio
function     bool FMixerPlatformXAudio2::GetOutputDeviceInfo

Source code excerpt:

		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::FrontCenter);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::LowFrequency);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::BackLeft);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::BackRight);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::SideLeft);
		OutInfo.OutputChannelArray.Add(EAudioMixerChannel::SideRight);
		return true;
#endif 
	}

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/WindowsMMDeviceInfoCache.cpp:136

Scope (from outer to inner):

file
namespace    Audio
function     bool FWindowsMMDeviceCache::EnumerateChannelMask

Source code excerpt:

			EAudioMixerChannel::SideLeft,
			EAudioMixerChannel::SideRight,
			EAudioMixerChannel::BackLeft,
			EAudioMixerChannel::BackRight,
		};

		const EAudioMixerChannel::Type* ChannelOrdering = DefaultChannelOrdering;

		// Override channel ordering for some special cases

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/WindowsMMDeviceInfoCache.cpp:148

Scope (from outer to inner):

file
namespace    Audio
function     bool FWindowsMMDeviceCache::EnumerateChannelMask

Source code excerpt:

				EAudioMixerChannel::FrontLeft,
				EAudioMixerChannel::FrontRight,
				EAudioMixerChannel::BackLeft,
				EAudioMixerChannel::BackRight,
			};

			ChannelOrdering = DefaultChannelOrderingQuad;
		}
		else if (OutInfo.NumChannels == 6)

#Loc: <Workspace>/Engine/Source/Runtime/Windows/AudioMixerXAudio2/Private/WindowsMMDeviceInfoCache.cpp:161

Scope (from outer to inner):

file
namespace    Audio
function     bool FWindowsMMDeviceCache::EnumerateChannelMask

Source code excerpt:

				EAudioMixerChannel::FrontCenter,
				EAudioMixerChannel::LowFrequency,
				EAudioMixerChannel::BackLeft,
				EAudioMixerChannel::BackRight,
			};

			ChannelOrdering = DefaultChannelOrdering51;
		}