Because ZS4 can export video in Motion PNG format, a lossless format which stores transparency, it is a good idea to save your footage with key to import into larger ZS4 projects.

In this tutorial we shall do that using a person in front of a greenscreen and a chroma key. You can download the video clip here (4mb). This was saved (with ZS4) in mjpeg format, so you may not be able to play the file back with wmp, but you should be able to import it into ZS4 to use in this tutorial.

Step 1
Start ZS4 by clicking on the desktop icon. You will see that the default tab is the file tab. Here you can find files on your hard drive which are compatible with ZS4. (eg. avi, wav, png, jpg, zs4 project files) Alternatively, use the file dialog which can be launched by clicking the file open button at the bottom left (see screenshot).

Once you have located the file you wish to import, click on it. We'll assume you use the provided footage which is called onmyplanet.avi.


 
Step 2
The video should appear in a matter of seconds under the Import tab. For longer pieces of footage, you may have to wait for the wave form to be drawn before you can bring the footage into the track display area. The full wave form can be viewed by clicking the audio tab.

To bring it into the project, drag the green arrow either into the left or right lower area. If you drag it into the tree view, it will always be a child track of the main mixer (project track) which for the purposes of this tutorial is what we want. (If you drag a file onto another track in the track display, it will become a child track of that one, which will be apparent in the tree view.)


 
Step 3
As you can see, the video track is quite a bit smaller than the output frame size. The mixer track has a default frame size of 720x576 (PAL DV) but this can be changed by clicking the i icon on the mixer track in the track display to bring up the track properties tab.


 
Step 4
We will change the video dimensions of the mixer to match the video, since we do not need the extra space. The video is 240x180, so type those dimensions into the track dimensions input fields and press update.


 
Step 5
Now click on the f/x tab (next to the project tree view tab) and find the yuv/chroma key.  Its in the effects/video effects/pixel filters/keying filters folder. Drag it onto the video clip. This makes the effect track a child track of the video which makes it slaved to that track (same length, moves with its parent). Child tracks are drawn from the bottom up on top of their parents.


 
Step 6
When you added the chroma key effect, the tab in the track arrangement window switched to the current tab, which shows the currently selected track (red). It does this so you can set the effect settings.

Press the colour selector toggle in (button with green rectangle on it) and then draw with the mouse to select a large colour sample from the area we want to key.


 
Step 7
The default settings do a pretty good job on this footage, but if you wanted to adjust them, you can click on the tolerance strips in the var area. For finer control, click the settings icon next to the next key frame icon (far right).


 
Step 8
Click on the f/x tab again and look in the video effects/convolution filters folder for the key smoother. Drag it onto the onmyplanet.avi track. It will appear above the yuv key, which is what we want.


 
Step 9
The current tab is showing again. If you want to smooth more of the edge, adjust the matrix value setting, keeping in mind that higher values will slow your progress down exponentially. I recommend staying within the lower 1/4.


 
Step 10
To export this footage with transparency intact, click on the export button of the main media mixer.


 
Step 11
Type the path and file name you want to save to where it says output-file. Or, use the browse button to choose a folder and file name.

On this page you can also change output size and frame rate. Press export once you are finished.


 
Step 12
On the next screen you will be able to pick the export encoder. Press the arrow keys until you find the MPNG encoder. This is the only one which preserves the transparency of the video.

Now press enter and wait for a while until its done processing.

Recommended use for this exported video is to import it back into ZS4 along with some other footage as backdrop etc.