Gif frame timing is not always obeyed

[sjudd]

Sample URLs:

http://giphy.com/gifs/horror-cartoon-simpsons-WJfhOzOgXOLle
http://media1.giphy.com/media/WJfhOzOgXOLle/giphy.gif

[sjudd]

We're not the only ones to have this problem, great discussion around Mozilla's defaults from a while ago: https://bugzilla.mozilla.org/show_bug.cgi?id=125137

[sjudd]

A couple of points.

1. We need to choose a default and/or a minimum timing, some GIFs will write 0, some will write between 1 and 10 (hundredths of a second) and expect it to be 10 because that's IE's minimum.
2. -1 for a frame delay is supposed to indicate display forever. Definitely less critical to obey this.

I'm inclined to follow IE and set 10 100ths of a second as the minimum frame delay. It's slow, but our decoder is limited to maybe one frame every 30 ms at best anyway and it will save battery life.

[sjudd]

Here's a nice set of samples showing how modern browsers handle these values:

http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum-frame-delay-browser-compatibility.

After testing 100ms per frame is too slow. I'll set the minimum at 30ms and default to 100ms for GIFs with a frame delay set to less than 30ms.