Make an AVI file from the JPG frames

We've checked our animation and the movie is complete. (Okay, it's short and not an Oscar contender but hey, this is a quick demonstration...) But - our animation is a series of jpg images, not a movie file. Everybody and everything in the digital world expects movies to be one file containing all the frames (and a soundtrack and sometimes more, too). So how do we get there?

Well (as usual with computers) there's lots of different ways. Very often video editing programs can treat a folder full of images as a movie file. (You might even have one that does.) For this exercise, though, I'm looking for a free way to turn our frames into a movie.

Windows Movie Maker is free with Windows and can import images. Unfortunately, it wants to bring them in as slides in a slideshow, with each frame remaining on screen for seconds at a time. It would be very tedious to have to fix every image so it was on screen at the frame rate we'd like; there has to be a better way.

There is. The open source (and free) program VirtualDubMod can do the job. To find it, you can Google for it, or download VirtualDubMod from this link.

Double click on the VirtualDubMod icon you've created and the program will open, looking completely mysterious.

To get started: go to the File menu and select Open Video File. A standard Windows File dialog will open. Navigate to the folder containing the jpg files of your animation, and click on the first jpg file in the animation.

When you click on Open, VirtualDubMod will load all of the images in the sequence and look like this, with two views of the movie, the one on the right mostly hidden.

The next job is to set the frame rate of our animation. From the Video menu choose Frame Rate... and a dialog with lots of options will open.

Under Source rate adjustment select the option Change to ____ frames per second, and enter the frame rate you want for the animation.

We'll preview the animation in a moment, and you can change the frame rate until you're satisfied with the way the animation plays. Ignore all the other options; the default settings are what we want. I chose 10 frames per second for my animation. Click on OK to return to the main VirtualDubMod window.

To check the video playback speed, click on the playback arrow button labeled with the letter I (for Input) at the lower left of the VirtualDubMod window. After you play the animation, you'll have to move the position slider all the way to the left to play it again.

Optional step: Scale the video to 320x240

We could make our video file right now. In fact, I recommend it for a reason you'll see in Part Four of this project. But if you want to do a little more work, read the next section; if not, skip ahead to Create the video file.

If we made the video file now, it would have the same pixel dimensions as the original jpg files - 640 x 480 in my case. But YouTube and Google video are much happier when the videos you upload measure 320 x 240. If you upload a different size file, they'll convert the file to 320 x 240. This takes time, and means that you'll have to wait a while before you can proudly email your video link to your friends. So I like to give the video hosts what they want - a video that's 320 x 240.

VirtualDubMod can fix this by scaling the movie. Go back to the Video menu and select Filters.

The Filters dialog will open, with a completely empty list, like this.

Click on the Add button, and a list of all the things you can do to the pictures will open.

Find the entry 2:1 reduction (high quality) and double click on it to add it to the list of applied filters. Click OK on the Filters list to go back to the main window. Drag the right edge of the VirtualDubMod window open and you'll see the processed frames. (Aha! That's why there are two views of the movie in VirtualDubMod.)

Create the video file

We're finally ready to make our AVI file. On the File menu choose Save As... and a dialog opens.

Choose where you want to save the file and what you want to call it. Make sure that the type is Audio-Video Interleave (*.avi), and go down to the Video options. Notice that the Compression default is (Uncompressed RGB). This is a good choice if you're going to be editing the movie in a video editing program, but it makes very large files that are slow to upload.

Click on the Change command button to open a dialog showing all the compression options available to you.

Here's where we choose just how our video will be compressed. This list will look different on your computer; it depends on what programs you have on your machine. I'm going to use a codec that comes with Windows, so all of you will have it - the Cinepak Codec by Radius. I'm comfortable with this codec, through having used it for years; it does an acceptable job. If you have a different favorite, feel free to use it. Double click on the codec and click the OK button to return to the Save As dialog.

You'll see the compression setting has changed. Now - drum roll - click on the Save button and VirtualDubMod will turn the jpg image sequence into an AVI file. (Cymbal crash!) Play the finished file back in a media player to make sure it's OK. You're now set to upload your animation and share it with the world.