>Since you have transparency, you can make each frame transparent, and lay them on top of each other; which allows more efficient temporal compression. There i

>Since you have transparency, you can make each frame transparent, and lay them on top of each other; which allows more efficient temporal compression. There is simply no way that you are going to achieve more efficient compression with that crude technique than with the algorithms used by modern video codecs. I also think that losslessness is probably relatively low concern with an animation. The transparency thing is important, although that is achievable with video as well. WebM is apparently going to support it directly one of these days, but the cross-browser way is to store the alpha channel in a separate half of the frame and combine them using an off-screen canvas. (Edit: see this demo: http://jakearchibald.com/scratch/alphavid/ http://jakearchibald.com/scratch/alphavid/)