| UsdMedia module — pxr-usd-api 105.1 documentation | |
| pxr-usd-api | |
| » | |
| Modules » | |
| UsdMedia module | |
| # UsdMedia module | |
| Summary: The UsdMedia module provides a representation for including other media, such as audio, in the context of a stage. UsdMedia currently contains one media type, UsdMediaSpatialAudio, which allows the playback of audio files both spatially and non-spatially. | |
| Classes: | |
| SpatialAudio | |
| The SpatialAudio primitive defines basic properties for encoding playback of an audio file or stream within a USD Stage. | |
| Tokens | |
| class pxr.UsdMedia.SpatialAudio | |
| 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. | |
| Although authored layer offsets may have a time scale which can scale | |
| the duration between an authored startTime and endTime, we make no | |
| attempt to infer any playback dilation of the actual audio media | |
| itself. Given that startTime and endTime can be independently | |
| authored in different layers with differing time scales, it is not | |
| possible, in general, to define an”original timeframe”from which we | |
| can compute a dilation to composed stage-time. Even if we could | |
| compute a composed dilation this way, it would still be impossible to | |
| flatten a stage or layer stack into a single layer and still retain | |
| the composed audio dilation using this schema. | |
| Although we do not expect it to be common, it is possible to apply a | |
| negative time scale to USD layers, which mostly has the effect of | |
| reversing animation in the affected composition. If a negative scale | |
| is applied to a composition that contains authored startTime and | |
| endTime, it will reverse their relative ordering in time. Therefore, | |
| we stipulate when playbackMode | |
| is”onceFromStartToEnd”or”loopFromStartToEnd”, if endTime is less | |
| than startTime, then begin playback at endTime, and continue until | |
| startTime. When startTime and endTime are inverted, we do not, | |
| however, stipulate that playback of the audio media itself be | |
| inverted, since doing so”successfully”would require perfect knowledge | |
| of when, within the audio clip, relevant audio ends (so that we know | |
| how to offset the reversed audio to align it so that we reach | |
| the”beginning”at startTime), and sounds played in reverse are not | |
| likely to produce desirable results. | |
| For any described attribute Fallback Value or Allowed Values | |
| below that are text/tokens, the actual token is published and defined | |
| in UsdMediaTokens. So to set an attribute to the value”rightHanded”, | |
| use UsdMediaTokens->rightHanded as the value. | |
| Methods: | |
| CreateAuralModeAttr(defaultValue, writeSparsely) | |
| See GetAuralModeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreateEndTimeAttr(defaultValue, writeSparsely) | |
| See GetEndTimeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreateFilePathAttr(defaultValue, writeSparsely) | |
| See GetFilePathAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreateGainAttr(defaultValue, writeSparsely) | |
| See GetGainAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreateMediaOffsetAttr(defaultValue, ...) | |
| See GetMediaOffsetAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreatePlaybackModeAttr(defaultValue, ...) | |
| See GetPlaybackModeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| CreateStartTimeAttr(defaultValue, writeSparsely) | |
| See GetStartTimeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. | |
| Define | |
| classmethod Define(stage, path) -> SpatialAudio | |
| Get | |
| classmethod Get(stage, path) -> SpatialAudio | |
| GetAuralModeAttr() | |
| Determines how audio should be played. | |
| GetEndTimeAttr() | |
| 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. | |
| GetFilePathAttr() | |
| Path to the audio file. | |
| GetGainAttr() | |
| Multiplier on the incoming audio signal. | |
| GetMediaOffsetAttr() | |
| 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. | |
| GetPlaybackModeAttr() | |
| 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. | |
| GetSchemaAttributeNames | |
| classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken] | |
| GetStartTimeAttr() | |
| Expressed in the timeCodesPerSecond of the containing stage, startTime specifies when the audio stream will start playing during animation playback. | |
| CreateAuralModeAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreateEndTimeAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreateFilePathAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreateGainAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreateMediaOffsetAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreatePlaybackModeAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| CreateStartTimeAttr(defaultValue, writeSparsely) → Attribute | |
| 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 . | |
| Parameters | |
| defaultValue (VtValue) – | |
| writeSparsely (bool) – | |
| static Define() | |
| classmethod Define(stage, path) -> SpatialAudio | |
| Attempt to ensure a UsdPrim adhering to this schema at path is | |
| defined (according to UsdPrim::IsDefined() ) on this stage. | |
| If a prim adhering to this schema at path is already defined on | |
| this stage, return that prim. Otherwise author an SdfPrimSpec with | |
| specifier == SdfSpecifierDef and this schema’s prim type name for | |
| the prim at path at the current EditTarget. Author SdfPrimSpec s | |
| with specifier == SdfSpecifierDef and empty typeName at the | |
| current EditTarget for any nonexistent, or existing but not Defined | |
| ancestors. | |
| The given path must be an absolute prim path that does not contain | |
| any variant selections. | |
| If it is impossible to author any of the necessary PrimSpecs, (for | |
| example, in case path cannot map to the current UsdEditTarget ‘s | |
| namespace) issue an error and return an invalid UsdPrim. | |
| Note that this method may return a defined prim whose typeName does | |
| not specify this schema class, in case a stronger typeName opinion | |
| overrides the opinion at the current EditTarget. | |
| Parameters | |
| stage (Stage) – | |
| path (Path) – | |
| static Get() | |
| classmethod Get(stage, path) -> SpatialAudio | |
| Return a UsdMediaSpatialAudio holding the prim adhering to this schema | |
| at path on stage . | |
| If no prim exists at path on stage , or if the prim at that | |
| path does not adhere to this schema, return an invalid schema object. | |
| This is shorthand for the following: | |
| UsdMediaSpatialAudio(stage->GetPrimAtPath(path)); | |
| Parameters | |
| stage (Stage) – | |
| path (Path) – | |
| GetAuralModeAttr() → Attribute | |
| 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 | |
| GetEndTimeAttr() → Attribute | |
| 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 | |
| GetFilePathAttr() → Attribute | |
| 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). | |
| Usdz Specification | |
| Declaration | |
| uniform asset filePath = @@ | |
| C++ Type | |
| SdfAssetPath | |
| Usd Type | |
| SdfValueTypeNames->Asset | |
| Variability | |
| SdfVariabilityUniform | |
| GetGainAttr() → Attribute | |
| 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 | |
| GetMediaOffsetAttr() → Attribute | |
| 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 | |
| GetPlaybackModeAttr() → Attribute | |
| 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 | |
| static GetSchemaAttributeNames() | |
| classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken] | |
| Return a vector of names of all pre-declared attributes for this | |
| schema class and all its ancestor classes. | |
| Does not include attributes that may be authored by custom/extended | |
| methods of the schemas involved. | |
| Parameters | |
| includeInherited (bool) – | |
| GetStartTimeAttr() → Attribute | |
| 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 | |
| class pxr.UsdMedia.Tokens | |
| Attributes: | |
| auralMode | |
| endTime | |
| filePath | |
| gain | |
| loopFromStage | |
| loopFromStart | |
| loopFromStartToEnd | |
| mediaOffset | |
| nonSpatial | |
| onceFromStart | |
| onceFromStartToEnd | |
| playbackMode | |
| spatial | |
| startTime | |
| auralMode = 'auralMode' | |
| endTime = 'endTime' | |
| filePath = 'filePath' | |
| gain = 'gain' | |
| loopFromStage = 'loopFromStage' | |
| loopFromStart = 'loopFromStart' | |
| loopFromStartToEnd = 'loopFromStartToEnd' | |
| mediaOffset = 'mediaOffset' | |
| nonSpatial = 'nonSpatial' | |
| onceFromStart = 'onceFromStart' | |
| onceFromStartToEnd = 'onceFromStartToEnd' | |
| playbackMode = 'playbackMode' | |
| spatial = 'spatial' | |
| startTime = 'startTime' | |
| © Copyright 2019-2023, NVIDIA. | |
| Last updated on Nov 14, 2023. | |