UsdMediaSpatialAudio#

Fully qualified name: usdrt::UsdMediaSpatialAudio

class UsdMediaSpatialAudio : public usdrt::UsdGeomXformable #

The SpatialAudio primitive defines basic properties for encoding playback of an audio file or stream within a USD Stage. The SpatialAudio schema derives from UsdGeomXformable since it can support full spatial audio while also supporting non-spatial mono and stereo sounds. One or more SpatialAudio prims can be placed anywhere in the namespace, though it is advantageous to place truly spatial audio prims under/inside the models from which the sound emanates, so that the audio prim need only be transformed relative to the model, rather than copying its animation.

Timecode Attributes and Time Scaling#

startTime and endTime are timecode valued attributes which gives them the special behavior that layer offsets affecting the layer in which one of these values is authored are applied to the attribute’s value itself during value resolution. This allows audio playback to be kept in sync with time sampled animation as the animation is affected by layer offsets in the composition. But this behavior brings with it some interesting edge cases and caveats when it comes to layer offsets that include scale.

Public Functions

inline explicit UsdMediaSpatialAudio(const UsdPrim &prim = UsdPrim())#: Construct a UsdMediaSpatialAudio on UsdPrim prim. Equivalent to UsdMediaSpatialAudio::Get(prim.GetStage(), prim.GetPath()) for a valid prim , but will not immediately throw an error for an invalid prim.

inline explicit UsdMediaSpatialAudio(const UsdSchemaBase &schemaObj)#: Construct a UsdMediaSpatialAudio on the prim held by schemaObj . Should be preferred over UsdMediaSpatialAudio(schemaObj.GetPrim()), as it preserves SchemaBase state.

inline virtual ~UsdMediaSpatialAudio()#: Destructor.

inline UsdAttribute GetFilePathAttr() const#

Path to the audio file. In general, the formats allowed for audio files is no more constrained by USD than is image-type. As with images, however, usdz has stricter requirements based on DMA and format support in browsers and consumer devices. The allowed audio filetypes for usdz are M4A, MP3, WAV (in order of preference).


Declaration	`uniform asset filePath = @@`
C++ Type	SdfAssetPath
Usd Type	SdfValueTypeNames->Asset
Variability	SdfVariabilityUniform

See also

Usdz Specification

inline UsdAttribute CreateFilePathAttr() const#: See GetFilePathAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetAuralModeAttr() const#

Determines how audio should be played. Valid values are:

spatial: Play the audio in 3D space if the device can support spatial audio. if not, fall back to mono.
nonSpatial: Play the audio without regard to the SpatialAudio prim’s position. If the audio media contains any form of stereo or other multi-channel sound, it is left to the application to determine whether the listener’s position should be taken into account. We expect nonSpatial to be the choice for ambient sounds and music sound-tracks.


Declaration	`uniform token auralMode = "spatial"`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Variability	SdfVariabilityUniform
Allowed Values	spatial, nonSpatial

inline UsdAttribute CreateAuralModeAttr() const#: See GetAuralModeAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetPlaybackModeAttr() const#

Along with startTime and endTime, determines when the audio playback should start and stop during the stage’s animation playback and whether the audio should loop during its duration. Valid values are:

onceFromStart: Play the audio once, starting at startTime, continuing until the audio completes.
onceFromStartToEnd: Play the audio once beginning at startTime, continuing until endTime or until the audio completes, whichever comes first.
loopFromStart: Start playing the audio at startTime and continue looping through to the stage’s authored endTimeCode.
loopFromStartToEnd: Start playing the audio at startTime and continue looping through, stopping the audio at endTime.
loopFromStage: Start playing the audio at the stage’s authored startTimeCode and continue looping through to the stage’s authored endTimeCode. This can be useful for ambient sounds that should always be active.


Declaration	`uniform token playbackMode = "onceFromStart"`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Variability	SdfVariabilityUniform
Allowed Values	onceFromStart, onceFromStartToEnd, loopFromStart, loopFromStartToEnd,

loopFromStage |

inline UsdAttribute CreatePlaybackModeAttr() const#: See GetPlaybackModeAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetStartTimeAttr() const#

Expressed in the timeCodesPerSecond of the containing stage, startTime specifies when the audio stream will start playing during animation playback. This value is ignored when playbackMode is set to loopFromStage as, in this mode, the audio will always start at the stage’s authored startTimeCode. Note that startTime is expressed as a timecode so that the stage can properly apply layer offsets when resolving its value. See Timecode Attributes and Time Scaling for more details and caveats.


Declaration	`uniform timecode startTime = 0`
C++ Type	SdfTimeCode
Usd Type	SdfValueTypeNames->TimeCode
Variability	SdfVariabilityUniform

inline UsdAttribute CreateStartTimeAttr() const#: See GetStartTimeAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetEndTimeAttr() const#

Expressed in the timeCodesPerSecond of the containing stage, endTime specifies when the audio stream will cease playing during animation playback if the length of the referenced audio clip is longer than desired. This only applies if playbackMode is set to onceFromStartToEnd or loopFromStartToEnd, otherwise the endTimeCode of the stage is used instead of endTime. If endTime is less than startTime, it is expected that the audio will instead be played from endTime to startTime. Note that endTime is expressed as a timecode so that the stage can properly apply layer offsets when resolving its value. See Timecode Attributes and Time Scaling for more details and caveats.


Declaration	`uniform timecode endTime = 0`
C++ Type	SdfTimeCode
Usd Type	SdfValueTypeNames->TimeCode
Variability	SdfVariabilityUniform

inline UsdAttribute CreateEndTimeAttr() const#: See GetEndTimeAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetMediaOffsetAttr() const#

Expressed in seconds, mediaOffset specifies the offset from the referenced audio file’s beginning at which we should begin playback when stage playback reaches the time that prim’s audio should start. If the prim’s playbackMode is a looping mode, mediaOffset is applied only to the first run-through of the audio clip; the second and all other loops begin from the start of the audio clip.


Declaration	`uniform double mediaOffset = 0`
C++ Type	double
Usd Type	SdfValueTypeNames->Double
Variability	SdfVariabilityUniform

inline UsdAttribute CreateMediaOffsetAttr() const#: See GetMediaOffsetAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetGainAttr() const#

Multiplier on the incoming audio signal. A value of 0 “mutes” the signal. Negative values will be clamped to 0.


Declaration	`double gain = 1`
C++ Type	double
Usd Type	SdfValueTypeNames->Double

inline UsdAttribute CreateGainAttr() const#: See GetGainAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetXformOpOrderAttr() const#

Encodes the sequence of transformation operations in the order in which they should be pushed onto a transform stack while visiting a UsdStage’s prims in a graph traversal that will effect the desired positioning for this prim and its descendant prims.

You should rarely, if ever, need to manipulate this attribute directly. It is managed by the AddXformOp(), SetResetXformStack(), and SetXformOpOrder(), and consulted by GetOrderedXformOps() and GetLocalTransformation().


Declaration	`uniform token[] xformOpOrder`
C++ Type	VtArray<TfToken>
Usd Type	SdfValueTypeNames->TokenArray
Variability	SdfVariabilityUniform

inline UsdAttribute CreateXformOpOrderAttr() const#: See GetXformOpOrderAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetVisibilityAttr() const#

Visibility is meant to be the simplest form of “pruning” visibility that is supported by most DCC apps. Visibility is animatable, allowing a sub-tree of geometry to be present for some segment of a shot, and absent from others; unlike the action of deactivating geometry prims, invisible geometry is still available for inspection, for positioning, for defining volumes, etc.


Declaration	`token visibility = "inherited"`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Allowed Values	inherited, invisible

inline UsdAttribute CreateVisibilityAttr() const#: See GetVisibilityAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdAttribute GetPurposeAttr() const#

Purpose is a classification of geometry into categories that can each be independently included or excluded from traversals of prims on a stage, such as rendering or bounding-box computation traversals.

See UsdGeom_ImageablePurpose for more detail about how purpose is computed and used.


Declaration	`uniform token purpose = "default"`
C++ Type	TfToken
Usd Type	SdfValueTypeNames->Token
Variability	SdfVariabilityUniform
Allowed Values	default, render, proxy, guide

inline UsdAttribute CreatePurposeAttr() const#: See GetPurposeAttr(), and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.

inline UsdRelationship GetProxyPrimRel() const#

The proxyPrim relationship allows us to link a prim whose purpose is “render” to its (single target) purpose=”proxy” prim. This is entirely optional, but can be useful in several scenarios:

In a pipeline that does pruning (for complexity management) by deactivating prims composed from asset references, when we deactivate a purpose=”render” prim, we will be able to discover and additionally deactivate its associated purpose=”proxy” prim, so that preview renders reflect the pruning accurately.

DCC importers may be able to make more aggressive optimizations for interactive processing and display if they can discover the proxy for a given render prim.

With a little more work, a Hydra-based application will be able to map a picked proxy prim back to its render geometry for selection.

Note

It is only valid to author the proxyPrim relationship on prims whose purpose is “render”.

inline UsdRelationship CreateProxyPrimRel() const#: See GetProxyPrimRel(), and also Create vs Get Property Methods for when to use Get vs Create.

UsdPrim GetPrim() const#: Return this schema object’s held prim.

SdfPath GetPath() const#: Return the SdfPath to this schema object’s held prim.

inline explicit operator bool() const#

Check if this schema object is compatible with it’s held prim and that the prim is valid.

A typed schema object is compatible if the held prim’s type is or is a subtype of the schema’s type. Based on prim.IsA().

An API schema object is compatible if the API is of type SingleApplyAPI or UsdSchemaType::MultipleApplyAPI, and the schema has been applied to the prim. Based on prim.HasAPI.

This method invokes polymorphic behaviour.