Stretch CHOP

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Summary

The Stretch CHOP preserves the shape of channels and the sampling rate, but resamples the channels into a new interval. All data in the range is stretched or compressed to the new start and end positions.

A Reverse Interval parameter reverses the order of the samples of each channel.

PythonIcon.pngstretchCHOP_Class


Parameters - Stretch Page

Interpolation interp - - The interpolation method to use when resampling.

  • No Interpolation nointerp - Use the value of the nearest sample.
  • Linear linear - Use linear interpolation between samples when the interval is lengthened. Averages all samples near the new sample when the interval is shortened.
  • Cubic cubic - Cubically interpolates between samples, for smoother curves than Linear. This method is not recommended for channels with sharp changes.
  • Pulse Preserve edge - A linear interpolation that recognizes single sample pulses and preserves their height and one sample width. A pulse is a non-zero value preceded and followed by zero-value samples.

Constant Area constarea - If enabled, keeps the area under the channel constant by scaling the values of the channel.

Unit Values relative - - Determines how Start/End parameters are interpreted:

  • Absolute abs - The value is the new start/end position.
  • Relative to Start/End rel - The value is a shift from the old start/end position.
  • Relative to Current Frame cur -

Start start - The CHOP's new start position.  

Start Unit startunit - -

End end - The CHOP's new end position.  

End Unit endunit - -

Length Scale scale - Scales the length of the channel after determining the start/end interval. Good for doubling or halving the length.  

Reverse Interval reverse - Reverses the channel so that it plays backwards.



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.

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).



CHOPs
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An Operator Family which operate on Channels (a series of numbers) which are used for animation, audio, mathematics, simulation, logic, UI construction, and many other applications.

To pulse a parameter is to send it a signal from a CHOP or python or a mouse click that causes a new action to occur immediately. A pulse from a CHOP is typically a 0 to 1 to 0 signal in a channel, and a pulse via python is via a .pulse() call on a pulse-type parameter, such as Reset in a Speed CHOP.

The term "Frame" is used (1) in the Timeline, (2) as a time-unit in CHOPs, (3) as a time-unit in TOPs, and (4) with movies images which are read and created with TOPs.

A Time Slice is the time from the last cook frame to the current cook frame. In CHOPs it is the set of short channels that only contain the CHOP channels' samples between the last and the current cook frame.

A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator.

samples-per-second of a CHOP. Each CHOP in your network has a sample rate, whether it is used or not. The overall timeline has a "frame rate", which is the number of animation frames per second, generally your monitor display frequency.

Exporting is the connection of CHOP channels to parameters of operators. The output of each exporting CHOP is one or more channels, active only while the CHOP Viewer is on. The current value of a channel can be exported to a parameter of any operator, overriding that parameter's value. See Parameter.

An Operator Family that manipulates text strings: multi-line text or tables. Multi-line text is often a command Script, but can be any multi-line text. Tables are rows and columns of cells, each containing a text string.

The location of an operator within the TouchDesigner environment, for example, /geo1/torus1, a node called torus1 in a component called geo1. The path / is called Root. To refer instead to a filesystem folder, directory, disk file or http: address, see Folder.

Parameters in TouchDesigner are an operator's settings (numbers, menus, flags, strings, paths) which the user can alter. Parameters for any operator can be opened by right-clicking on the operator and selecting "Parameters..." A currently selected operator's parameters can be viewed in a Network Editor by pressing the keyboard shortcut 'p'.

TouchDesigner is a hierarchy of components. "root" is the top-most network in the hierarchy. The Path is simply /. A typical path is /project1/moviein1.