使用物理音频空间引擎 (PHASE) 探索几何感知音频

18:31 - Create an Engine and Register a Sound Asset

// Create an Engine in Automatic Update Mode.
let engine = PHASEEngine(updateMode: .automatic)

// Retrieve the URL to an Audio File stored in our Application Bundle.
let audioFileUrl = Bundle.main.url(forResource: "DrumLoop_24_48_Mono", withExtension: "wav")!

// Register the Audio File at the URL.
// Name it "drums", load it into resident memory and apply dynamic normalization to prepare it for playback.
let soundAsset = try engine.assetRegistry.registerSoundAsset(url: audioFileUrl,
                                                             identifier: "drums",
                                                             assetType: .resident,
                                                             channelLayout: nil,
                                                             normalizationMode: .dynamic)

20:47 - Register a Sound Event Asset

// Create a Channel Layout from a Mono Layout Tag.
let channelLayout = AVAudioChannelLayout(layoutTag: kAudioChannelLayoutTag_Mono)!
     
// Create a Channel Mixer from the Channel Layout.
let channelMixerDefinition = PHASEChannelMixerDefinition(channelLayout: channelLayout)

// Create a Sampler Node from "drums" and hook it into the downstream Channel Mixer.
let samplerNodeDefinition = PHASESamplerNodeDefinition(soundAssetIdentifier: "drums",
                                                       mixerDefinition: channelMixerDefinition)

// Set the Sampler Node's Playback Mode to Looping.
samplerNodeDefinition.playbackMode = .looping;

// Set the Sampler Node's Calibration Mode to Relative SPL and Level to 0 dB.
samplerNodeDefinition.setCalibrationMode(.relativeSpl, level: 0)

// Register a Sound Event Asset with the Engine named "drumEvent".
let soundEventAsset = try engine.assetRegistry.registerSoundEventAsset(rootNode:samplerNodeDefinition,
                                             identifier: "drumEvent")

22:21 - Start a Sound Event

// Create a Sound Event from the Sound Event Asset "drumEvent".
let soundEvent = try PHASESoundEvent(engine: engine, assetIdentifier: "drumEvent")

// Start the Engine.
// This will internally start the Audio IO Thread.
try engine.start()

// Start the Sound Event.
try soundEvent.start()

23:05 - Cleanup

// Stop and invalidate the Sound Event.
soundEvent.stopAndInvalidate()

// Stop the Engine.
// This will internally stop the Audio IO Thread.
engine.stop()

// Unregister the Sound Event Asset.
engine.assetRegistry.unregisterAsset(identifier: "drumEvent", completionHandler:nil)

// Unregister the Audio File.
engine.assetRegistry.unregisterAsset(identifier: "drums", completionHandler:nil)

// Destroy the Engine.
engine = nil

25:14 - Create a Sound Event Asset

// Create a Spatial Pipeline.
let spatialPipelineOptions: PHASESpatialPipeline.Options = [.directPathTransmission, .lateReverb]
let spatialPipeline = PHASESpatialPipeline(options: spatialPipelineOptions)!
spatialPipeline.entries[PHASESpatialCategory.lateReverb]!.sendLevel = 0.1;
engine.defaultReverbPreset = .mediumRoom

// Create a Spatial Mixer with the Spatial Pipeline.
let spatialMixerDefinition = PHASESpatialMixerDefinition(spatialPipeline: spatialPipeline)

// Set the Spatial Mixer's Distance Model.
let distanceModelParameters = PHASEGeometricSpreadingDistanceModelParameters()
distanceModelParameters.fadeOutParameters = PHASEDistanceModelFadeOutParameters(cullDistance: 10.0)
distanceModelParameters.rolloffFactor = 0.25
spatialMixerDefinition.distanceModelParameters = distanceModelParameters

// Create a Sampler Node from "drums" and hook it into the downstream Spatial Mixer.
let samplerNodeDefinition = PHASESamplerNodeDefinition(soundAssetIdentifier: "drums", mixerDefinition:spatialMixerDefinition)

// Set the Sampler Node's Playback Mode to Looping.
samplerNodeDefinition.playbackMode = .looping

// Set the Sampler Node's Calibration Mode to Relative SPL and Level to 12 dB.
samplerNodeDefinition.setCalibrationMode(.relativeSpl, level: 12)

// Set the Sampler Node's Cull Option to Sleep.
samplerNodeDefinition.cullOption = .sleepWakeAtRealtimeOffset;

// Register a Sound Event Asset with the Engine named "drumEvent".
let soundEventAsset = try engine.assetRegistry.registerSoundEventAsset(rootNode: samplerNodeDefinition, identifier: "drumEvent")

27:05 - Set Up a Listener

// Create a Listener.
let listener = PHASEListener(engine: engine)

// Set the Listener's transform to the origin with no rotation.
listener.transform = matrix_identity_float4x4;

// Attach the Listener to the Engine's Scene Graph via its Root Object.
// This actives the Listener within the simulation.
try engine.rootObject.addChild(listener)

27:46 - Set Up a Volumetric Source

// Create an Icosahedron Mesh.
let mesh = MDLMesh.newIcosahedron(withRadius: 0.0142, inwardNormals: false, allocator:nil)

// Create a Shape from the Icosahedron Mesh.
let shape = PHASEShape(engine: engine, mesh: mesh)

// Create a Volumetric Source from the Shape.
let source = PHASESource(engine: engine, shapes: [shape])

// Translate the Source 2 meters in front of the Listener and rotated back toward the Listener.
var sourceTransform: simd_float4x4
sourceTransform.columns.0 = simd_make_float4(-1.0, 0.0, 0.0, 0.0)
sourceTransform.columns.1 = simd_make_float4(0.0, 1.0, 0.0, 0.0)
sourceTransform.columns.2 = simd_make_float4(0.0, 0.0, -1.0, 0.0)
sourceTransform.columns.3 = simd_make_float4(0.0, 0.0, 2.0, 1.0)
source.transform = sourceTransform;

// Attach the Source to the Engine's Scene Graph.
// This actives the Listener within the simulation.
try engine.rootObject.addChild(source)

29:15 - Set Up an Occluder

// Create a Box Mesh.
let boxMesh = MDLMesh.newBox(withDimensions: simd_make_float3(0.6096, 0.3048, 0.1016),
                             segments: simd_uint3(repeating: 6),
                             geometryType: .triangles,
                             inwardNormals: false,
                             allocator: nil)

// Create a Shape from the Box Mesh.
let boxShape = PHASEShape(engine: engine, mesh:boxMesh)

// Create a Material.
// In this case, we'll make it 'Cardboard'.
let material = PHASEMaterial(engine: engine, preset: .cardboard)

// Set the Material on the Shape.
boxShape.elements[0].material = material

// Create an Occluder from the Shape.
let occluder = PHASEOccluder(engine: engine, shapes: [boxShape])
    
// Translate the Occluder 1 meter in front of the Listener and rotated back toward the Listener.
// This puts the Occluder half way between the Source and Listener.
var occluderTransform: simd_float4x4
occluderTransform.columns.0 = simd_make_float4(-1.0, 0.0, 0.0, 0.0)
occluderTransform.columns.1 = simd_make_float4(0.0, 1.0, 0.0, 0.0)
occluderTransform.columns.2 = simd_make_float4(0.0, 0.0, -1.0, 0.0)
occluderTransform.columns.3 = simd_make_float4(0.0, 0.0, 1.0, 1.0)
occluder.transform = occluderTransform

// Attach the Occluder to the Engine's Scene Graph.
// This actives the Occluder within the simulation.
try engine.rootObject.addChild(occluder)

30:33 - Start a Spatial Sound Event

// Associate the Source and Listener with the Spatial Mixer in the Sound Event.
let mixerParameters = PHASEMixerParameters()
mixerParameters.addSpatialMixerParameters(identifier: spatialMixerDefinition.identifier, source: source, listener: listener)

// Create a Sound Event from the built Sound Event Asset "drumEvent".
let soundEvent = try PHASESoundEvent(engine: engine, assetIdentifier: "drumEvent", mixerParameters: mixerParameters)

31:28 - Example 1: Footstep on creaky wood

// Create a Sampler Node from "footstep_wood_clip_1" and hook it into a Channel Mixer.
let footstep_wood_sampler_1 = PHASESamplerNodeDefinition(soundAssetIdentifier: "footstep_wood_clip_1", mixerDefinition: channelMixerDefinition)

31:54 - Example 2: Random footsteps on creaky wood

// Create a Sampler Node from "footstep_wood_clip_1" and hook it into a Channel Mixer.
let footstep_wood_sampler_1 = PHASESamplerNodeDefinition(soundAssetIdentifier: "footstep_wood_clip_1", mixerDefinition: channelMixerDefinition)

// Create a Sampler Node from "footstep_wood_clip_2" and hook it into a Channel Mixer.
let footstep_wood_sampler_2 = PHASESamplerNodeDefinition(soundAssetIdentifier: "footstep_wood_clip_2", mixerDefinition: channelMixerDefinition)

// Create a Random Node.
// Add 'Footstep on Creaky Wood' Sampler Nodes as children of the Random Node.
// Note that higher weights increase the likelihood of that child being chosen.
let footstep_wood_random = PHASERandomNodeDefinition()
footstep_wood_random.addSubtree(footstep_wood_sampler_1, weight: 2)
footstep_wood_random.addSubtree(footstep_wood_sampler_2, weight: 1)

32:47 - Example 3: Random footsteps on creaky wood or soft gravel

// Create a Sampler Node from "footstep_gravel_clip_1" and hook it into a Channel Mixer.
let footstep_gravel_sampler_1 = PHASESamplerNodeDefinition(soundAssetIdentifier: "footstep_gravel_clip_1", mixerDefinition: channelMixerDefinition)

// Create a Sampler Node from "footstep_gravel_clip_2" and hook it into a Channel Mixer.
let footstep_gravel_sampler_2 = PHASESamplerNodeDefinition(soundAssetIdentifier: "footstep_gravel_clip_2", mixerDefinition: channelMixerDefinition)

// Create a Random Node.
// Add 'Footstep on Soft Gravel' Sampler Nodes as children of the Random Node.
// Note that higher weights increase the likelihood of that child being chosen.
let footstep_gravel_random = PHASERandomNodeDefinition()
footstep_gravel_random.addSubtree(footstep_gravel_sampler_1, weight: 2)
footstep_gravel_random.addSubtree(footstep_gravel_sampler_2, weight: 1)

// Create a Terrain String MetaParameter.
// Set the default value to "creaky_wood".
let terrain = PHASEStringMetaParameterDefinition(value: "creaky_wood")

// Create a Terrain Switch Node.
// Add 'Random Footstep on Creaky Wood' and 'Random Footstep on Soft Gravel' as Children.
let terrain_switch = PHASESwitchNodeDefinition(switchMetaParameterDefinition: terrain)
terrain_switch.addSubtree(footstep_wood_random, switchValue: "creaky_wood")
terrain_switch.addSubtree(footstep_gravel_random, switchValue: "soft_gravel")

34:08 - Example 4: Random footsteps on changing terrain with a variably wet surface

// Create a Sampler Node from "splash_clip_1" and hook it into a Channel Mixer.
let splash_sampler_1 = PHASESamplerNodeDefinition(soundAssetIdentifier: "splash_clip_1", mixerDefinition: channelMixerDefinition)
    
// Create a Sampler Node from "splash_clip_2" and hook it into a Channel Mixer.
let splash_sampler_2 = PHASESamplerNodeDefinition(soundAssetIdentifier: "splash_clip_2", mixerDefinition: channelMixerDefinition)

// Create a Random Node.
// Add 'Splash' Sampler Nodes as children of the Random Node.
// Note that higher weights increase the likelihood of that child being chosen.
let splash_random = PHASERandomNodeDefinition()
splash_random.addSubtree(splash_sampler_1, weight: 9)
splash_random.addSubtree(splash_sampler_2, weight: 7)

// Create a Wetness Number MetaParameter.
// The range is [0, 1], from dry to wet. The default value is 0.5.
let wetness = PHASENumberMetaParameterDefinition(value: 0.5, minimum: 0, maximum: 1)
    
// Create a 'Wetness' Blend Node that blends between dry and wet terrain.
// Add 'Terrain' Switch Node and 'Splash' Random Node as children.
// As you increase the wetness, the mix between the dry footsteps and splashes will change.
let wetness_blend = PHASEBlendNodeDefinition(blendMetaParameterDefinition: wetness)
wetness_blend.addRangeForInputValues(belowValue: 1, fullGainAtValue: 0, fadeCurveType: .linear, subtree: terrain_switch)
wetness_blend.addRangeForInputValues(aboveValue: 0, fullGainAtValue: 1, fadeCurveType: .linear, subTree: splash_random)

35:53 - Example 5: Random footsteps on changing terrain with a variably wet surface and noisy Gore-Tex Jacket

// Create a Sampler Node from "gortex_clip_1" and hook it into a Channel Mixer.
let noisy_clothing_sampler_1 = PHASESamplerNodeDefinition(soundAssetIdentifier: "gortex_clip_1", mixerDefinition: channelMixerDefinition)

// Create a Sampler Node from "gortex_clip_2" and hook it into a Channel Mixer.
let noisy_clothing_sampler_2 = PHASESamplerNodeDefinition(soundAssetIdentifier: "gortex_clip_2", mixerDefinition: channelMixerDefinition)

// Create a Random Node.
// Add 'Noisy Clothing' Sampler Nodes as children of the Random Node.
// Note that higher weights increase the likelihood of that child being chosen.
let noisy_clothing_random = PHASERandomNodeDefinition()
noisy_clothing_random.addSubtree(noisy_clothing_sampler_1, weight: 3)
noisy_clothing_random.addSubtree(noisy_clothing_sampler_2, weight: 5)

// Create a Container Node.
// Add 'Wetness' Blend Node and 'Noisy Clothing' Random Node as children.
let actor_container = PHASEContainerNodeDefinition()
actor_container.addSubtree(wetness_blend)
actor_container.addSubtree(noisy_clothing_random)