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This CHOP reads in channel and audio files for use by CHOPs.
The types of files that can be read into chops include:
Raw ascii channel files; a row of numbers per frame.
Raw PRISMS/Houdini binary channel files.
Houdini native CHOP clip files.
Houdini native non-commercial CHOP clip files.
Houdini channel segment files.
.aif .aiff .au .sf .snd .wav .mp3
The same files can be output from the menu on the CHOP tile by selecting Save Data Channels. For a complete listing of all valid formats for CHOPs, see the Formats section.
Other Input Devices
Users can extend the file formats that are read/written by the File chop through the chop io and CLIPio files in $HFS/houdini. Use the clchan and clchn programs as examples of the input/output needed.
The name of the file to load. The button beside the string field brings up a file browser.
Reload the channel file to react to external changes to it.
Allows you to change the way the channels are named.
Use Names In File
Uses the channel names stored in the file. If the format does not support names (ie. sound files), then chan0, chan1, chan2, etc. is used.
Use New Names
The channel names are manually specified by the name parameter below.
The filename, minus the extension and path, is used. If more than 1 channel is in the file, the channels will be numbered to keep the names unique.
The new name(s) of the file’s channels.
Allows you to change the sample rate of the file.
Use the file’s sample rate.
Change the file’s sample rate to a new rate.
Change the file’s sample rate to a new rate and keep the time range constant.
The new sample rate to use if Override or Resample is selected.
The extend condition before the channel’s beginning.
The extend condition after the channel’s ending.
The value of the default value extend condition.
Some of these parameters may not be available on all CHOP nodes.
To determine which channels get affected, some CHOPs have a scope string. Patterns can be used in the scope, for example
* (match all), and
? (match single character).
The following are examples of possible channel name matching options:
Matches a single channel name.
chan3 tx ty tz
Matches four channel names, separated by spaces.
Matches each channel that starts with
Matches each channel that has
foot in it.
? matches a single character.
t? matches two-character channels starting with t.
Matches number ranges giving
[xyz]matches three characters, giving channels
Sample Rate Match
The Sample Rate Match Options handle cases where multiple input CHOPs’ sample rates are different.
Resample At First Input’s Rate
Use rate of first input to resample others.
Resample At Maximum Rate
Resample to highest sample rate.
Resample At Minimum Rate
Resample to the lowest sample rate.
Error if Rates Differ
Does not accept conflicting sample rates.
The units for which time parameters are specified.
For example, you can specify the amount of time a lag should last for in seconds (default), frames (at the Houdini FPS), or samples (in the CHOP’s sample rate).
When you change the Units parameter, it does not convert the existing parameters to the new units.
Time Slicing is a feature which boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel does need to be evaluated every frame, then cooking the entire range of the channel is unnecessary. It is more efficient to calculate only the fraction of the channel that is needed. This fraction is known as a Time Slice.
Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.
The Export prefix is prepended to CHOP channel names to determine where to export to.
For example, if the CHOP channel was named
geo1:tx, and the prefix was
/obj, the channel would be exported to
You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as
Every CHOP has this option. Each CHOP gets a default color assigned for display in the Graph port, but you can override the color in the Common page under Graph Color. There are 36 RGB color combinations in the Palette.
Graph Color Step
When the graph displays the animation curves and a CHOP has two or more channels, this defines the difference in color from one channel to the next, giving a rainbow spectrum of colors.