To give the impression of falling rain, I suggest two methods, each of which have their advantages and disadvantages.

1st method : Using an existing HFX

To achieve this end, I chose to use the Pinnacle Hollywood FX software. I created 2 "transitions" (Pluie5s and Pluie10s) Pluie means Rain in English, which will be used as a plug-in. This short tutorial is designed to teach you how to use these 2 "transitions".

For this tutorial, I used the 2nd clip of the demonstration film Clowns.mpg that ships with Studio.

In the tutorial "Simulating snow (transition #244)" we used the method which was to duplicate the clip to insert the transition between the two identical clips.

Today, I propose the Loosecannon method which consists of using the HFX Filter.

After inserting your clip on the timeline, you apply the video effect in the HFX Filter category RTFX Studio Plus.
Then you edit the HFX Filter by clicking on the icon. After a few seconds, the Hollywood FX software will open.

Now, we will have to choose between Pluie5s and Pluie10s (Rain5s and Rain10s). The Pluie5s effect was designed to be applied to a clip of 2 to 5 seconds length. The Pluie10s effect was designed to be applied to a clip of 6 to 10 seconds length. But nothing prevents you from using Pluie10s on a clip of 5 seconds, the rain will be quickly transformed into a flood ... Of course if you use the Pluie5s clip which is about 10 seconds, the rain will fall more slowly and the effect will be much less realistic.

I will leave it to you to test all the combinations that are available to you. You can even make a selection of several clips to apply the effect all at one time. You can also apply Pluie10s to a clip of 20 seconds: in this case you cut your clip in two, you select the 2 sides split in the clip you apply Pluie10s on both sides of the clip 20 seconds. Your imagination will do the rest ...

Now that you've watched the different in-depth tutorials relating to the creation and modification of HFX effects, you can also modify the "effect" used. This change is very easy, it is only necessary to change the flight path& (hence the envelope) of the null object "Trajectoire." In modifying that envelope, you can speed up or slow down the speed, and thus the strength of the rain. You can even create a Pluie15s. I think you should be able to accomplish this on your own now.

When you decided which to use, double-click the image of the effect to load it in the HFX tree.

After you have made your choice in HFX, click on OK, and you are back in Studio with the effect applied to the clip(s) selected.

The rain has now stopped falling ... You still have to save your work, to make an AVI file and review your work.

Then, you insert the resulting file, which will serve as a plug-in for your project,

The main drawback of this method lies in the fact that "the color of the rain" is not adjustable and, as such, does not always give a good effect on some backgrounds. However, it is very easy to implement.

Method 2: Use of an existing AVI file

To make this effect, I chose to use an animation of 30 pictures, created with graphics software and photo retouching. I created Pluie.AVI, a small file that will be used in your editing. You can copy it, in the download, the file Pluie.avi.

This short tutorial is designed to teach you how to use this AVI file.

For this tutorial, I used the 5th the film clip in the demonstration video Clowns.mpg provided with Studio.

So, step by step, here is how to create your effect:

After placing the 5th clip on the main track of the timeline, you then place the Pluie.AVI file on the overlay track.
Pluie.AVI consists of 30 pictures, which gives a length of 1 second if editing as an NTSC file or 1 second and 6 frames if it's a PAL video.
We will apply the Chroma Keyer effect to this video clip with the parameters shown so you see the rain and ensure it is not tinged with green.
Depending on the background (5th clip), it may be necessary to apply an additional "Color Correction".That's what I did here.
Finally, you may have to add another supplementary video effect "Speed" to accelerate or reduce the speed of the rain..
If you are happy with your settings, your time line, should look like this:
We need to duplicate the adjusted clip, which is on the overlay track, as many times as necessary to equal the length of the clip on the main video track. (You select the clip to duplicate, then CTRL + C to copy this clip to the clipboard, and then CTRL + V as many times as needed to achieve the desired result).

Remember to save your work, and to make an AVI file for this.

Okay, that's it ... easy?

{Thanks to Loosecannon for the fine tuning}