I have discovered to play this animated PNG using Irfanview (which I use), or the google Chrome browser (which I also use). However, Facebook doesn't like them allowing only animated GIFs. There is NOTHING wrong with your application! I am glad to have had the opportunity to post a comment here. The animated PNG format allows for many more colors to be displayed than GIFs. Cheers!
I have assembled 48 PNG images together to make an animated PNG but the output file "animated.png" will not animate. It remains a static image. What am I doing wrong? Is there special software required to "play" the animated.png output file?