Network channel node

Similar to the Pipe In/Out CHOPs in Network mode.

This CHOP is similar to the Pipe In/Out CHOPs in Network mode. It provides a fast, asynchronous connection between two remote Houdini processes. The CHOP operates in either Transmit or Receive mode.

A connection is establish between a client Network CHOP and a server Network CHOP. By default, the Transmitting Network CHOP is the server; however, if the parameter “Default Client/Server Setup” is off, the Receiving Network CHOP becomes the server. Both the Transmitting and Receiving CHOPs must choose the same client/server setup. This option is mainly for interfacing with external applications; if you are transmitting from Houdini to Houdini, you do not need to change this parameter.

The server Network CHOP (normally the Transmitter) selects a port number between 5000 and 10000. The client Network CHOP (the receiver) then connects to the server by setting the address to the server hostname, and the port to the same port as the server Network CHOP.

The Transmitting Network CHOP requires an input to transmit. Transmission occurs whenever the input changes, or if in Current Frame or Time Slice mode, whenever the playbar moves. The Network CHOP can choose a Data Link mode to send the current frame only (for low bandwidth situations), the current time slice (for realtime applications) or the full channel. Both the Transmitting and Receiving CHOPs should use the same “Data Link” mode.

The Receiving Network CHOP receives all of the data from the Transmitter. However, if the CHOP is not actively reading the data (by cooking) it will pile up in the buffer. By default, the maximum buffer size is 1000 samples per channel (the limit can be disabled).

Parameters

Network

Direction

Transmit or Receive data. When transmitting, an input is required.

Default Client/Server Setup

When on, the Transmitting CHOP is the server; when off, it is the client (see above).

Address

The address of the remote server.

Port

The port to use (between 5000 and 10000). You can have multiple parallel connections as long as the port numbers are distinct. A transmitter/receiver pair must use the same port.

Data Link

The portion of data to send over the link.

Current Frame Only	Sends the value of the current frame (1 sample per channel).
Current Time Slice	Sends the portion of the channel from the last cook time to the current cook time.
Full Channel	Sends all the data in all the channels.

Endian

Transmit either Little Endian format data (Intel) or Big Endian (MIPs, PowerPC).

Active

Data is only transmitted or received when this toggle is on.

Channel

Send Channel Names	Sends the channel names as well as the data if on.
Receive Most Recent Data	Uses the most recently sent data. If the buffer contains 10 samples and 4 are required, the most recent 4 are used and the previous 6 are lost.
Limit Input Buffer Size	Places a limitation on the size of the receive buffer (defined by the next parameter).
Buffer Size	The maximum number of samples that the receive buffer can hold (per channel).

Common

Some of these parameters may not be avaiable on all CHOP nodes.

Scope

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:

`chan2`	Matches a single channel name.
`chan3 tx ty tz`	Matches four channel names, separated by spaces.
`chan*`	Matches each channel that starts with `chan`.
`foot`	Matches each channel that has `foot` in it.
`t?`	The `?` matches a single character. `t?` matches two-character channels starting with t.
`r[xyz]`	Matches channels `rx`, `ry` and `rz`.
`blend[3-7:2]`	Matches number ranges giving `blend3`, `blend5`, and `blend7`.
`blend[2-3,5,13]`	Matches channels `blend2`, `blend3`, `blend5`, `blend13`.
`t[xyz]`	`[xyz]`matches three characters, giving channels `tx`, `ty` and `tz`.

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.

Units

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).

Note

When you change the Units parameter, it does not convert the existing parameters to the new units.

Time Slice

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.

Unload

Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.

Export Prefix

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 /obj/geo1/tx.

Note

You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as obj:geo1:tx.

Graph Color

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.

Usages in other examples

Example name	Example for