CompressionQualityModifier

CompressionQualityModifier

#Overview

name: CompressionQualityModifier

The value of this variable can be defined or overridden in .ini config files. 1 .ini config file referencing this setting variable.

It is referenced in 14 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of CompressionQualityModifier is to adjust the compression quality of audio assets when cooking (preparing for deployment) for specific platforms in Unreal Engine 5. It allows developers to scale the compression quality across all audio assets for a particular target platform.

CompressionQualityModifier is primarily used in the audio system of Unreal Engine, specifically in the audio compression and cooking processes. It is referenced in various platform-specific settings classes (UWindowsTargetSettings, UAndroidRuntimeSettings, UIOSRuntimeSettings) and the audio platform configuration system.

The value of this variable is typically set in the platform-specific settings for each target platform. For example, it can be set in the Windows, Android, or iOS project settings within the Unreal Engine editor.

This variable interacts with the base compression quality of individual audio assets. The final compression quality is calculated by multiplying the asset’s base quality with the CompressionQualityModifier.

Developers should be aware that:

  1. The default value is 1.0, which leaves the original compression quality unchanged.
  2. Values less than 1.0 will reduce the overall compression quality, while values greater than 1.0 will increase it.
  3. This setting affects all audio assets for the target platform, so it should be used judiciously.

Best practices when using this variable include:

  1. Use it to fine-tune audio quality vs. file size trade-offs for specific platforms.
  2. Test thoroughly after adjusting this value to ensure audio quality remains acceptable.
  3. Consider platform-specific requirements and limitations when setting this value.
  4. Document any non-default values used in the project to maintain consistency across the development team.

#Setting Variables

#References In INI files

Location: <Workspace>/Projects/Lyra/Config/DefaultEngine.ini:320, section: [/Script/WindowsTargetPlatform.WindowsTargetSettings]

#References in C++ code

#Callsites

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

#Loc: <Workspace>/Engine/Source/Developer/Windows/WindowsTargetPlatform/Classes/WindowsTargetSettings.h:136

Scope (from outer to inner):

file
class        class UWindowsTargetSettings : public UObject

Source code excerpt:

	/** Scales all compression qualities when cooking to this platform. For example, 0.5 will halve all compression qualities, and 1.0 will leave them unchanged. */
	UPROPERTY(GlobalConfig, EditAnywhere, Category = "Audio|CookOverrides")
	float CompressionQualityModifier;

	/** When set to anything beyond 0, this will ensure any SoundWaves longer than this value, in seconds, to stream directly off of the disk. */
	UPROPERTY(GlobalConfig)
	float AutoStreamingThreshold;

	/** Quality Level to COOK SoundCues at (if set, all other levels will be stripped by the cooker). */

#Loc: <Workspace>/Engine/Source/Developer/Windows/WindowsTargetPlatform/Private/WindowsTargetPlatformClasses.cpp:13

Scope (from outer to inner):

file
function     UWindowsTargetSettings::UWindowsTargetSettings

Source code excerpt:

	, LowSampleRate(12000)
	, MinSampleRate(8000)
	, CompressionQualityModifier(1)
{
	// Default windows settings
	AudioSampleRate = 48000;
	AudioCallbackBufferFrameSize = 1024;
	AudioNumBuffersToEnqueue = 1;
	AudioNumSourceWorkers = 4;

#Loc: <Workspace>/Engine/Source/Runtime/Android/AndroidRuntimeSettings/Classes/AndroidRuntimeSettings.h:636

Scope (from outer to inner):

file
class        class UAndroidRuntimeSettings : public UObject

Source code excerpt:

	// Scales all compression qualities when cooking to this platform. For example, 0.5 will halve all compression qualities, and 1.0 will leave them unchanged.
	UPROPERTY(config, EditAnywhere, Category = "Audio|CookOverrides")
	float CompressionQualityModifier;

	// When set to anything beyond 0, this will ensure any SoundWaves longer than this value, in seconds, to stream directly off of the disk.
	UPROPERTY(GlobalConfig)
	float AutoStreamingThreshold;

	// Several Android graphics debuggers require configuration changes to be made to your application in order to operate. Choosing an option from this menu will configure your project to work with that graphics debugger.

#Loc: <Workspace>/Engine/Source/Runtime/Android/AndroidRuntimeSettings/Private/AndroidRuntimeSettings.cpp:38

Scope (from outer to inner):

file
function     UAndroidRuntimeSettings::UAndroidRuntimeSettings

Source code excerpt:

    , LowSampleRate(12000)
	, MinSampleRate(8000)
	, CompressionQualityModifier(1)
	, bMultiTargetFormat_ETC2(true)
	, bMultiTargetFormat_DXT(true)
	, bMultiTargetFormat_ASTC(true)
	, TextureFormatPriority_ETC2(0.2f)
	, TextureFormatPriority_DXT(0.6f)
	, TextureFormatPriority_ASTC(0.9f)

#Loc: <Workspace>/Engine/Source/Runtime/AudioPlatformConfiguration/Private/AudioCompressionSettings.cpp:53

Scope (from outer to inner):

file
function     void FPlatformAudioCookOverrides::GetHashSuffix

Source code excerpt:

	}

	FPCU::AppendHash(OutSuffix, TEXT("QMOD"), InOverrides->CompressionQualityModifier);
	FPCU::AppendHash(OutSuffix, TEXT("CQLT"), InOverrides->SoundCueCookQualityIndex);
	FPCU::AppendHash(OutSuffix, TEXT("ASTH"), InOverrides->AutoStreamingThreshold);
	FPCU::AppendHash(OutSuffix, TEXT("INLC"), InOverrides->bInlineFirstAudioChunk);
	FPCU::AppendHash(OutSuffix, TEXT("LCK1"), InOverrides->LengthOfFirstAudioChunkInSecs);
	
	// FAudioStreamCachingSettings

#Loc: <Workspace>/Engine/Source/Runtime/AudioPlatformConfiguration/Public/AudioCompressionSettings.h:71

Scope: file

Source code excerpt:


	// Scales all compression qualities when cooking to this platform. For example, 0.5 will halve all compression qualities, and 1.0 will leave them unchanged.
	float CompressionQualityModifier;

	// If set, the cooker will keep only this level of quality
	int32 SoundCueCookQualityIndex = INDEX_NONE;

	// When set to any platform > 0.0, this will automatically set any USoundWave beyond this value to be streamed from disk.
	// If StreamCaching is set to true, this will be used

#Loc: <Workspace>/Engine/Source/Runtime/AudioPlatformConfiguration/Public/AudioCompressionSettings.h:93

Scope (from outer to inner):

file
function     FPlatformAudioCookOverrides

Source code excerpt:

	FPlatformAudioCookOverrides()
		: bResampleForDevice(false)
		, CompressionQualityModifier(1.0f)
		, AutoStreamingThreshold(0.0f)
		, bInlineFirstAudioChunk(false)
		, LengthOfFirstAudioChunkInSecs(0.f)
	{
		PlatformSampleRates.Add(ESoundwaveSampleRateSettings::Max, 48000);
		PlatformSampleRates.Add(ESoundwaveSampleRateSettings::High, 32000);

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/AudioCompressionSettingsUtils.cpp:157

Scope (from outer to inner):

file
function     void CacheAudioCookOverrides

Source code excerpt:

	}

	float CompressionQualityModifier = 0.0f;
	if (PlatformFile->GetFloat(*CategoryName, TEXT("CompressionQualityModifier"), CompressionQualityModifier))
	{
		OutOverrides.CompressionQualityModifier = CompressionQualityModifier;
	}

	float AutoStreamingThreshold = 0.0f;
	if (PlatformFile->GetFloat(*CategoryName, TEXT("AutoStreamingThreshold"), AutoStreamingThreshold))
	{
		OutOverrides.AutoStreamingThreshold = AutoStreamingThreshold;

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/AudioDerivedData.cpp:1602

Scope: file

Source code excerpt:

	float                       SampleRateOverride = -1.0f;
	bool                        bIsStreaming;
	float                       CompressionQualityModifier;
	FString						SoundWaveHash;
		
	TArray<Audio::FTransformationPtr> WaveTransformations;

	// Those are the only refs we keep on the actual USoundWave until
	// we have a mechanism in place to reference a bulkdata using a

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/AudioDerivedData.cpp:1627

Scope (from outer to inner):

file
function     FAudioCookInputs

Source code excerpt:

		, bIsSoundWaveProcedural(InSoundWave->IsA<USoundWaveProcedural>())
		, CompressionQuality(InSoundWave->GetCompressionQuality())
		, CompressionQualityModifier(InCookOverrides ? InCookOverrides->CompressionQualityModifier : 1.0f)
		, SoundWaveHash(GetSoundWaveHash(*InSoundWave, InTargetPlatform))
		, WaveTransformations(InSoundWave->CreateTransformations())
		, BulkDataCriticalSection(InSoundWave->RawDataCriticalSection)
		, BulkData(InSoundWave->RawData)
#endif
	{

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/AudioDerivedData.cpp:1787

Scope (from outer to inner):

file
function     static void CookSimpleWave

Source code excerpt:

	// Compression Quality
	FSoundQualityInfo QualityInfo = { 0 };	
	QualityInfo.Quality = CalculateModifiedCompressionQuality(Inputs.CompressionQuality, Inputs.CompressionQualityModifier);

	UE_CLOG(Inputs.CompressionQuality != QualityInfo.Quality, LogAudioDerivedData,
		Display, TEXT("Compression Quality for %s will be modified from %d to %d, with modifier [%.2f] "),
		*Inputs.SoundFullName, Inputs.CompressionQuality, QualityInfo.Quality, Inputs.CompressionQualityModifier);

	QualityInfo.NumChannels = NumChannels;
	QualityInfo.SampleRate = WaveSampleRate;
	QualityInfo.SampleDataSize = NumBytes;

	QualityInfo.bStreaming = Inputs.bIsStreaming;

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/AudioDerivedData.cpp:2036

Scope (from outer to inner):

file
function     static void CookSurroundWave

Source code excerpt:


	FSoundQualityInfo QualityInfo = { 0 };
	QualityInfo.Quality = CalculateModifiedCompressionQuality(Inputs.CompressionQuality,Inputs.CompressionQualityModifier);

	UE_CLOG(Inputs.CompressionQuality != QualityInfo.Quality, LogAudioDerivedData,
		Display, TEXT("Compression Quality for %s will be modified from %d to %d, with modifier [%.2f] "),
		*Inputs.SoundFullName, Inputs.CompressionQuality, QualityInfo.Quality, Inputs.CompressionQualityModifier);

	QualityInfo.NumChannels = ChannelCount;
	QualityInfo.SampleRate = WaveSampleRate;
	QualityInfo.SampleDataSize = SampleDataSize;
	QualityInfo.bStreaming = Inputs.bIsStreaming;
	QualityInfo.DebugName = Inputs.SoundFullName;

#Loc: <Workspace>/Engine/Source/Runtime/IOS/IOSRuntimeSettings/Classes/IOSRuntimeSettings.h:583

Scope (from outer to inner):

file
class        class UIOSRuntimeSettings : public UObject

Source code excerpt:

	// Scales all compression qualities when cooking to this platform. For example, 0.5 will halve all compression qualities, and 1.0 will leave them unchanged.
	UPROPERTY(config, EditAnywhere, Category = "Audio|CookOverrides")
	float CompressionQualityModifier;

	// When set to anything beyond 0, this will ensure any SoundWaves longer than this value, in seconds, to stream directly off of the disk.
	UPROPERTY(GlobalConfig)
	float AutoStreamingThreshold;

    virtual void PostReloadConfig(class FProperty* PropertyThatWasLoaded) override;

#Loc: <Workspace>/Engine/Source/Runtime/IOS/IOSRuntimeSettings/Private/IOSRuntimeSettings.cpp:23

Scope (from outer to inner):

file
function     UIOSRuntimeSettings::UIOSRuntimeSettings

Source code excerpt:

	, LowSampleRate(12000)
	, MinSampleRate(8000)
	, CompressionQualityModifier(1)
{
	bEnableGameCenterSupport = true;
	bEnableCloudKitSupport = false;
	bUserSwitching = false;
	bSupportsPortraitOrientation = true;
	bSupportsITunesFileSharing = false;