Audio Render CHOP

Summary

Note: For Apple Silicon Macs, this operator only works starting with build 2022.33910.

The Audio Render CHOP uses the Steam Audio SDK to spatially render audio based on the full transforms (translation, rotation, scale) of a listener and an audio source. The Audio Render CHOP takes sound audio sources as input, and spatially outputs the sound in the format specified from the Output Format parameter. The number of channels outputted by the Audio Render CHOP depends on the Output Format.

You specify a 3D component for the transform of the listener, plus a 3D component for the transform of a source.

The sample rate of the output is determined by the audio source, which must be either 44100 or 48000.

An Info DAT can be used to populate the position and radius of baked probes in Simulation mode.

Look at the Audio Render CHOP example in Help -> Operator Snippets.

Parameters - Audio Render Page

Active active - Turns the Audio Render on or off.

Mode mode - ⊞ - This menu determines which Steam Audio mode to use.

Simple Positional simple - Sound simulation for only a mono source.

Simulation simulation - Sound simulation for multiple sources.

Output Format outputformat - ⊞ - The output format of the audio.

Binaural Binaural - Spatialize sound based on 3D position of source relative to listener.

Stereo stereo - Spatialize sound based on left and right channels.

Quadraphonic Surround quadraphonic - Spatialize sound based on front left, front right, rear left, and rear right channels.

5.1 Surround fiveone - Spatialize sound based on front left, front right, front center, LFE, rear left, and rear right channels.

7.1 Surround sevenone - Spatialize sound based on Ffont left, front right, front center, LFE, rear left, rear right, side left, and side right channels.

Custom Setup custom - Custom Setup requires use of the Mapping Table.

Ambisonics ambisonics - Ambisonics is a format for encoding three-dimensional 360 degree audio. The Ambisonics format used in the Audio Render CHOP is the 3rd order SN3D format consisting of 16 encoded channels (WXYZ, RSTUV, KLMNOPQ) that define the sphere of sound. Ambisonics is disabled in Simulation mode when reflections are enabled.

Direct Effect direct - Used in Simulation mode only to simulate sound based on the direct path between a point source and listener. Direct Effect is disabled when reflections are enabled.

Enable Attenuation attenuation - Attenuate the sound based on the distance between the center position of the listener and a source. The attenuation level is determined by the selected attenuation mode for each source.

Ambisonics Order ambisonicsorder - Ambisonics order of the output buffer.

Mapping Table mappingtable - A DAT Table that specifies the various speakers in the setup and their position. The Table must have 3 columns named x, y, z. Each row specifies an individual speaker, and the 3 columns specify its position. Used with the Custom Setup Output Format. The mapping table will create one channel per row.

Listener Object COMP listenerobject - A COMP that represents the listening head. Must be a COMP that contains transform data, such as a Geometry or Camera COMP.

Source source - Sequence of the audio sources.

Object COMP source0object - A COMP that represents the source of the sound. Must be a 3D Object COMP that contains transform data, such as a Geometry COMP or Camera COMP.

Enable Directivity source0directivity - Turns directivity on or off. When disabled, sound will emit from the source from all directions (i.e. omnidirectional)

Dipole Weight source0dipoleweight - The weight of the dipole to blend in the directivity pattern. 0 = pure omnidirectional, 1 = pure dipole, 0.5 = cardioid directivity pattern.

Dipole Power source0dipolepower - The sharpness of the dipole. Higher values make the sound direction narrower.

Attenuation Mode source0attnmode - ⊞ - This menu determines which attenuation mode to use for the source. Note: Attenuation modes are disabled when reflections are enabled due to a known issue. If attenuation is enabled while reflections are on, it will revert to Steam Audio's default attenuation model of inverse distance with power of 1.

Inverse Distance inverse - Attenuation level is calculated by an inverse distance falloff function.

Custom Curve custom - Attenuation level is calculated by a custom curve.

Attenuation Inverse Power source0invpower - The power of the inverse falloff function. For example, a power of 2 causes an attenuation level of (1/distance)^2.

Attenuation Curve CHOP source0chop - The path of the custom attenuation curve CHOP being referenced. The CHOP must have exactly one channel to represent the curve. The vertical axis represents the attenuation level, and the horizontal axis represents the distance. Attenuation levels are clamped between [0, 1]. The distance should always be non-negative and assumes the CHOP is using samples as the unit.

Parameters - Meshes Page

Update Meshes update - When enabled, any static mesh changes will automatically be updated in the simulation

Update Meshes Pulse updatepulse - When pulsed, will update the static meshes in the simulation if they changed.

Mesh mesh - Sequence of static meshes.

Mesh Objects/POPs/SOPs mesh0object - The object for the mesh which can be geometry COMP, POP, or SOP. COMPs must contain SOP or POP geometries in triangle polygon form. The root COMP's display flag can be off and still be collected. However, child COMPs will only be added to the scene if their display flag is on.

Absorption mesh0absorb - ⊞ - The fraction of sound absorbed at low, medium, and high frequencies. 0 = no sound is absorbed, 1 = sound is fully absorbed by the mesh surface.

Absorption mesh0absorb1 - Absorption at low frequencies (0 - 800 Hz).

Absorption mesh0absorb2 - Absorption at medium frequencies (800 Hz - 8 kHz).

Absorption mesh0absorb3 - Absorption at high frequencies (8 kHz and above).

Scattering mesh0scatter - Scatters sound for reflections. 0 = reflect at the same angle as it hit the surface (i.e. pure specular), 1 = reflect uniformly randomly (i.e. pure diffuse).

Transmission mesh0trans - ⊞ - The fraction of sound transmitted through at low, medium, and high frequencies. 0 = no sound transmits through, 1 = sound fully transmits through the mesh surface.

Transmission mesh0trans1 - Transmission at low frequencies (0 - 800 Hz).

Transmission mesh0trans2 - Transmission at medium frequencies (800 Hz - 8 kHz).

Transmission mesh0trans3 - Transmission at high frequencies (8 kHz and above).

Parameters - Simulation Page

Enable Air Absorption airabsorb - Turns air absorption on or off for all sources. Air absorption is how much sound is lost over the distance travelling from source to listener.

Enable Occlusion occlusion - Turns raycast occlusion on or off for all meshes. If a single ray from listener to source is occluded, then the source is considered occluded.

Number of Surfaces numsurfaces - Maximum number of surfaces, starting from closest surface to the listener, whose transmission coefficients will be considered when calculating the total sound transmission.

Enable Reflection reflection - Turns reflection on or off for all meshes.

Diffuse Samples diffsamp - Number of directions to generate for reflecting rays.

Duration duration - Duration in seconds of the impulse responses generated.

Ambisonics Order refambixord - Ambisonics order of the impulse responses generated.

Number of Rays numrays - Number of rays to trace from the listener.

Number of Threads numthreads - Number of threads used for real-time reflection simulations.

Number of Bounces numbounces - Number of times each ray is reflected off a surface.

Irradiance Min Distance irmindist - The minimum distance used to calculate how much sound energy reaches a surface from a source.

Reflection Bake Mode bakemode - ⊞ - This menu determines which bake mode to use. Baking is useful as an optimization tool when calculating reflections. Baking will generate probes that are uniformly spaced and placed above any mesh "floor" at a fixed height. The mesh "floor" is meant to resemble a floor or terrain, meaning meshes should be horizontal or lie along the XZ plane for any probes to be generated on top of it. The probes' region of influence is defined by a 3D position and a radius. Baking has two variations: static listener and static source. For example, if static listener is selected, baking assumes the position of the listener remains fixed. Each probe is then baked reflection data that simulates the sound between its position and the listener. Once baking is done, sources can move around dynamically, and as long as they are within the range of any baked probe, they will use the probe's baked reflection data to calculate its reflected sound, allowing for a reduction in computation and simulation time. If a source is not within the range of any baked probe, the source will not be influenced by any baked data and can lead to incorrect sound calculations. All parameters used for reflections will also be used for baking. Baking will not generate probes for any of the following reasons: Scene has no geometry, spawn box does not contain any of the geometries in the scene, all probes generated lie outside of the spawn box, or all geometries are X-Y or Y-Z planar.

Off off - Baking is turned off. Turning baking off will disable any bakes that are currently active.

Manual manual - Baking is turned on, but Baked Reflections must be pulsed to start baking.

Automatic auto - Baking is turned on and will automatically start baking when changes to baking parameters have been made.

Bake Reflections bake - Immediately start baking. Once complete, reflections will automatically used the baked data. Baking status can be monitored using the bake_complete channel in the Info CHOP.

Baked Data Variation variation - ⊞ - This menu determines which objects will have a fixed position for baking. If the selected static object's position changes, you must re-bake or else the calculated reflections will be incorrect.

Static Listener listener - Each baking probe calculates reflections with the source at the probe position and the listener at some fixed position. The listener's position must stay static. This mode is useful for modeling reflections from a moving source to a static listener.

Static Source source - Each baking probe calculates reflections with the listener at the probe position and the source at some fixed position. The source's position must stay static. This mode is useful for modeling reflections from a moving listener to a static source.

Probes Distance probedist - The spacing between two neighboring probes.

Y-Offset from Surface yoffset - The height above the surface of a geometry all probes will be generated at.

Size of Spawn Box size - ⊞ - Size of the spawn box along the X, Y, and Z axes where probes will be generated.

Size of Spawn Box sizex -

Size of Spawn Box sizey -

Size of Spawn Box sizez -

Origin of Spawn Box origin - ⊞ - These X,Y, and Z Values determine where the center of the spawn box is located.

Origin of Spawn Box originx -

Origin of Spawn Box originy -

Origin of Spawn Box originz -

Distance from Listener lstnrdist - The maximum distance from the listener where baked data will be stored for probes.

Save Duration savedur - Duration in seconds of the impulse responses saved at each probe.

Batch Size batchsize - Number of probes to bake simultaneously.

Parameters - Common Page

Time Slice timeslice - Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.

Scope scope - To determine which channels get affected, some CHOPs use a Scope string on the Common page. See Pattern Matching.

Sample Rate Match srselect - ⊞ - Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.

Resample At First Input's Rate first - Use rate of first input to resample others.

Resample At Maximum Rate max - Resample to the highest sample rate.

Resample At Minimum Rate min - Resample to the lowest sample rate.

Error If Rates Differ err - Doesn't accept conflicting sample rates.

Export Method exportmethod - ⊞ - This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.

DAT Table by Index datindex - Uses the docked DAT table and references the channel via the index of the channel in the CHOP.

DAT Table by Name datname - Uses the docked DAT table and references the channel via the name of the channel in the CHOP.

Channel Name is Path:Parameter autoname - The channel is the full destination of where to export to, such has geo1/transform1:tx.

Export Root autoexportroot - This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.

Export Table exporttable - The DAT used to hold the export information when using the DAT Table Export Methods (See above).

Rename from commonrenamefrom - The channel pattern to rename. See Pattern Matching.

Rename to commonrenameto - The replacement pattern for the names. The default parameters do not rename the channels. See Pattern Replacement.

Example:

Channel Names: c[1-10:2] ambient

Rename From: c* ambient

Rename To: b[1-5] amb

This example fetches channels c1 c3 c5 c7 c9 and ambient.

They are then renamed to to b1 b2 b3 b4 b5 and amb.

See the Rename CHOP for a further description of rename patterns.

Operator Inputs

Input 0: -

Info CHOP Channels

Extra Information for the Audio Render CHOP can be accessed via an Info CHOP.

Specific Audio Render CHOP Info Channels

audioposition_full_time -

audioposition_panbin_time -

distance_attenuation -

Common CHOP Info Channels

start - Start of the CHOP interval in samples.

length - Number of samples in the CHOP.

sample_rate - The samplerate of the channels in frames per second.

num_channels - Number of channels in the CHOP.

time_slice - 1 if CHOP is Time Slice enabled, 0 otherwise.

export_sernum - A count of how often the export connections have been updated.

Common Operator Info Channels

total_cooks - Number of times the operator has cooked since the process started.

cook_time - Duration of the last cook in milliseconds.

cook_frame - Frame number when this operator was last cooked relative to the component timeline.

cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.

cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.

cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.

cooked_this_frame - 1 if operator was cooked this frame.

warnings - Number of warnings in this operator if any.

errors - Number of errors in this operator if any.

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