Ventuz Blog

Many peaple asked me how to retrieve “simple” XML data from a HTTP based server. Here you get an example…

The Weather Channel

The Weather Channel for example provides this kind of service (free of charge). They call it XOAP, XML Weather Feed.

To be able to receive data (for non-commercial use), you’ll need to sign up for an account (don’t worry! They won’t spam you)

http://registration.weather.com/registration/xmloap/step1

Most of those HTTP based XML feeds need a simple URL to query the data.
For TWC it looks like this:

http://xoap.weather.com/weather/local/[location]?cc=*&link=xoap&prod=xoap&par=[partnerID]&key=[password]&unit=m

The three fields (location, partnerID and password) have to be filled with the proper information. Without a valid account you won’t receive any data!
The location code can be found on the www.weather.com web site. Simply query a location and copy the code from your browsers address bar. Hamburg, Germany for example has the location code: GMXX0049

With the URL node of Ventuz its easy to construct this kind of URLs. The resulting URL is passed to an XML File node to receive the actual XML data. The Ventuz Express edition will stop rendering during this process, because it can’t handle the request in the background. The Broadcast/Professional editions don’t interfere the rendering, because the XML request is marked to be processed asynchronously.

Several XPath nodes are used to select the required information from the returned XML document. This values are “exposed” from the Container to make them easily accessible for other Ventuz nodes.

I’ve created a simple Ventuz Repository with some elements to acces TWC XML data. Simply download the repository here:

The Weather Channel REPOSITORY

… unzip it at you preferred location and open the Repository in you Project within the Ventuz Designer.

You’ll find 3 items:

• The “Weather Data” content node. This node hold all logic to receive the data and provides usefull output properties to handle/display the incoming data.
• The “Weather Icon” hierarchy node simply loads the correct icon texture depending on an icon number. The number matches exactly the icon codes of TWC.
• An “Example” scene, which show how you could use this two elements in conjunction with simple text fields and arrange nodesTo open the scene from the Repository, click on the “New Scene from Wizard” button and select “Example”.
  
  Btw, if you want to provide Scene-Templates within your own repositories, simply drag and drop the Scene-Root into it.
  As soon a user has opened that repository in his/her project, the “New Scene Wizard” will show all contained as available scene templates!

Have fun!

Ralf

Customer: “I need to display virtually any kind of content in my Ventuz presentation: my Fortran Compiler output, Word documents, Flash animations, etc…”

The Support Guy: “So you are a magican like David C. or Gandalf, aren´t you?”

Customer: “No! I´m unfortunately not!”

The Support Guy: “Ok, then visite www.hmelyoff.com .”

Customer: “OK, but how will this help me?”

The Support Guy: “They offer VH Screen Capture Driver which is a DirectShow filter, that emulates a Video Capture card and captures your screen.”

Customer: “You mean I could use it with the Live Video node and display the capturing as a texture?”

The Support Guy: “Absolutely right!”

Customer: “Are there any drawbacks?”

The Support Guy: “Hmmm…? No, not really. But don´t expect to capture in 60 Hz – in return it´s free!”

Customer: “Thanks! Good idea.”

Sometimes it is necessary to render textures in black & white. Doing this with an entire scene rendered to a texture before, can result in nice visual effects.
A few months ago I was asked to explain how that can be done in Ventuz. After playing around with the texture shading options, I found a solution for it.

I used four textures stages to get a cross-fade between the original texture and the bw version. The four stages do the following math operations:

• First we modulate (mix) the original texture color/alpha with the current diffuse (material)
• The 2nd stage multiplies all values by 0.5 and adds an offset of 0.5 (please note that the internal RGBA values are always interpreted as values from 0.0 to 1.0). The result of this stage is stored in the temp register to transfer it to the 3rd stage, where all values (RGB) are in the range from 0.5 to 1.0 now
• Stage 3 uses the Dot-Product to add the three RGB values together, multiplied by a constant weight value. The DotProduct operation interprets the RGB values (0.5-1.0) from the previous stage as signed values (-1.0 to +1.0). The unsigned values of stage 2 are converted that way:
  0.0 -> 1.0 are mapped/clipped to -1.0 -> +1.0, so our incoming values are interpreted as positive values from 0.0 to 1.0 now!
  The actual operation of the DotProduct is:   x = R*w + G*w + B*w, where the weight w is coming from the constant alpha. The result x is a scalar value stored in all three components (R, G and B) of the Temp register for further usage in stage 4
• The last stage (4) does a simple linear interpolation between the current register (result of stage 1) and the temp register (result of stage 2+3)
  The constant alpha is used as the interpolation pregress.

A simplified version of it (only 2 stages) can be used if you only need the BW version without cross-fading the colored and the bw texture:

Just remove stage 1 and connect the texture source (image loader) to stage 2, change the “Current” register to “TextureColor”, remove stage 4 and store the result of stage 3 in “Current” instead of “temp”

The 4-stage-scene can be downloaded here.

Ralf

The same solution for RGB/VGA/DVI as shown in my previous post is available from NTI Network Technology Inc.

NTI, DVI Quad Screen Splitter

In combination with the new DELTACAST-DVI input board and Ventuz a very interesting solution to feed in multiple HiRes signals.

By using two of these boxes, the two inputs of the deltacast will provide eight DVI signals in Ventuz – of course only 50% of their original resolution.

If you need to display multiple HD SDI signals in Ventuz, but the full resolution is not required (onair promotion and previews) you could use the DECIMATOR-QUAD from REDBYTE Design. This unit receives 4 SDI signals and combines them into a single output by scaling them down. The resulting SDI output gets captured by the DELTACAST HD boards into Ventuz Professional or Broadcast Edition. The second input of the DELTACAST board could be used to input one out of the four quads in full resolution. In combination with a synchronized 4×1 switcher controlled by Ventuz serial I/O nodes make this a very feasable solution for multiple video inputs.

Btw, these 4 inputs don’t need to be the same format and frequency!

We haven’t tested the box yet, but we would like to know your opinion or test results.

DECIMATOR-QUAD

JUST FIGURED OUT THAT THIS BOX ONLY PROVIDES SD ON OUTPUT – BUT STILL INTERESTING!