How To Define Frame Rnage Of File Channels?

[BrianK]

Say I've made a chan file that looks something like so:

20 3 4 5

21 3 4 5.1

22 3 4 5.2

etc...

If I load up this chan file using a file CHOP & then export the chop to some object, the first row of data goes to frame one. How can I make it go to frame 20?

[exel]

Hi BK,

Hmm. I know nothing about the .chan file format. Is your file CHOP creating a channel for your frame values? (20,21,22)? That's what it's doing for me, it creates a channel called "chan0" and puts 20,21,22 in it, and all the channels start at frame 1. I suppose you could append a shift CHOP:

Reference: Start Position

Unit Values: Absolute

Start: chopf("./chan0",1)

(Common Tab)Units: Frames

That's the first thing I came up with, <shrug>

-JS-

[BrianK]

Hi BK,

Hmm. I know nothing about the .chan file format. Is your file CHOP creating a channel for your frame values? (20,21,22)? That's what it's doing for me, it creates a channel called "chan0" and puts 20,21,22 in it, and all the channels start at frame 1. I suppose you could append a shift CHOP:

Reference: Start Position

Unit Values: Absolute

Start: chopf("./chan0",1)

(Common Tab)Units: Frames

Yes, it's doing what you say - a channel for the frame num.

I suppose I could use a shift... wish there was a way to define the shift in frames as opposed to seconds. hmmm..

[malexander]

Yes, it's doing what you say - a channel for the frame num.

I suppose I could use a shift... wish there was a way to define the shift in frames as opposed to seconds. hmmm..

You can. Every CHOP that uses time-based units has the 'Units' parameter on the common page enabled. Change it to frames.

If you wanted to use a slightly more involved format, you could write the data out in the Houdini .clip format:

{
	rate = <framerate>
	start = <startframe>
	tracklength = <# samples per channel (N) >
	tracks = <# channels>
	{
		name = <chan #1 name>
		data = <data1> <data2> .... <dataN>
	}
	{
		name = <chan #2 name>
		data = <data1> <data2> .... <dataN>
	}
}

This way, you could name your channels properly, so they export to the right spot, and you can incorporate your shift by setting start to 20. Of course, the extra formatting may not be worth it unless you're loading LOTS of channel files.

So, your above example would look like (assuming the first column is actually frame #'s and not data):

{
   rate = 24
   start = 20
   tracklength = 3
   tracks = 3
   {
	   name = tx
	   data = 3 4 5
   }
   {
	   name = ty
	   data = 3 4 5.1
   }
   {
	  name = tz
	  data = 3 4 5.2
   }
}

[BrianK]

You can. Every CHOP that uses time-based units has the 'Units' parameter on the common page enabled. Change it to frames.

If you wanted to use a slightly more involved format, you could write the data out in the Houdini .clip format:

The clip format looks perfect & is an easy change to the script that spits out this data.

Thanks on both accounts - units and clips.