Make an AVI file from the JPG frames - Mac

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.

iMovie comes with the Mac, and it can import images. Unfortunately, it wants to bring them in as slides in a slideshow, with a minimum duration of 1 second. It would be very tedious to fix each image to show for the correct time. There has to be a better way.

There is, it’s called Avidemux, and it’s a free, open-source program. You can Google for it, or download Avidemux from this link. The download is the version that I installed on my Mac. It’s a completely normal Mac install – nothing tricky about it.

Open Avidemux and you’ll see the main program window, looking mysterious. There’s no useful help file for the program – I find that this is common with open source software. We’ll only be using a few of its features, so this isn’t a big problem.

To get started: go to the File menu and select Open... . A file open dialog will appear, looking a little different than the typical Mac dialog.

Navigate to the folder with your frames and select the first frame in the shot. Click on Open; Avidemux will load all of the images in the sequence, and look like this.

Next, set the frame rate of the animation. From the Video menu choose Frame Rate. A nice straightforward dialog will open.

Set the frame rate to whatever you want. I’ve chosen 10 frames per second for my animation. You can preview the animation in Avidemux and change this rate to whatever suits you best. To preview the animation, just click on the Play button in the lower left corner. After the animation finishes, you’ll have to move the position slider back to the start position to play it again.

Now there’s an optional step. We could make our video file right now, and 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 file with different pixel dimensions, 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.

The easiest way to do this is by scaling all the jpeg frames before you bring them into Avidemux. I haven’t been able to find a consistent way to get the program to do it for me, and Photoshop and other image editors make scaling easy.

Making the animation at 640x480 and then having the video host do the conversion doesn’t make much of a penalty, especially with this little project. With bigger projects you’ll be using programs that can give the output you want, so we’ll leave the output at 640x480 for now.

One more check – look at the left edge of the Avidemux main window.

Make sure that the Video drop down is set to Copy and the Format is AVI. These are the default settings, so they should be OK, but it's wise to check.

Avidemux shares the Mac software designer’s habit of shielding you from some of what’s happening inside movie (and other) files. Our original files are JPG images, and Copy seems to tell Avidemux to encode the final video as motion jpg. At least that’s what my editing software says comes out of this process.

I leave the output at AVI because it works. There are other options but I’d rather be animating than exploring the quirks of an open source program.

The moment of truth: choose File -> Save and yet another dialog will open.

Go to where you want the file and give it a name. Be sure to add the .avi extension to the file name. If you do, the Mac will recognize it, play it back in Quicktime and import it into iMovie. If you don’t add the extension, the file is just another unrecognizable bunch of bytes cluttering up your drive. You can add the extension after you’ve made the file, and Quicktime and iMovie will recognize it.

Click on Save and Avidemux will make your file – all set for the next step. And it’s also ready for importing into iMovie, where you can polish your masterpiece and add sound. But even as-is, it can be loaded to one of the video hosts and shared with the world.