When creating animations directly from 3DVIA Composer or SolidWorks Animator, you create an AVI file. Depending on the output options you use, the resulting frames can be compressed a certain amount; however, even if you do this, AVI files are not small, nor can they be played by a wide variety of systems and devices. What else can you do?
One option is to render each frame as a seperate graphic, which is a great way to go if you're working with a video compositing software such as Adobe Premiere or Sony Vegas Video. But what if you just want to dump out the animation "as-is" in a more portable format?
The answer, my friends, is a little open-source software program called Handbrake. This little gem is free and works on Windows as well as Mac. All you have to do is tell it what file to process and where you want to the file to go. From there, using the default settings, it'll give you a size-matched MP4 version of your input AVI, which will look just as good as the original, but will be much smaller. And, as a bonus, it'll play on just about any device or platform you throw it on, from web pages to iPads.
How good is it? As an example, I saved a 20-second animation from 3DVIA Composer to an uncompressed AVI file, which ended up being 2.3 gigabytes. After running that file through Handbrake, the resulting MP4 file is visually identical to the original, but it's just 2.9 megabytes. Yes, you read that correctly -- the resulting file was nearly 1/100th the size. It's like one of those miracle gadgets you see on late-night TV, except this one works! Did I mention it's also free?
How do you get this miracle software? Just point your web browser to http://handbrake.fr/ and download it. Then, enjoy a life of small video files with ultimate cross-platform compatibility.