Browsers and GIF animations

When I began using gifsicle instead of whirlgif to generate my animations, I wondered if gifsicle's better-optimized products would still display correctly in the common browsers. So I went to the library to try their computers, which have a wider variety of user agents than I have installed on my own machines.

I quickly found that some of my animations — even the old ones made by whirlgif — failed to display correctly on Microsoft's Internet Explorer : instead of taking the correct amount of time, they ran about a factor of two too slowly. For example, the Standard-Atmosphere [“textbook”] green flash was quite sluggish. But the Mozilla (and Firefox) browsers displayed the animations correctly.

Here are some examples; try them with your browser, and see if they work properly. You can re-start all the animations by clicking on the browser's “Reload” button.

Skip to the start of the animations.

Here are the animations; each should run 10 seconds, and repeat 5 times.

Each series begins with a title, displayed for 2 seconds, that tells the interval between frames in the 8-second animation that follows. After the title, there's a seconds' count, from 1 to 8. The animations that display each frame for only a fraction of a second have a little dot that crawls across the frame below the big digit that shows the number of the second.


I've found that Firefox, Google Chrome, and most other browsers display all the sequences nicely in sync, even on the old 800-MHz Pentium II machine on my desk on campus — and even on Windows machines, proving that the problem is in Microsoft's browser, not its OS. But Microsoft's IE can't keep up when the inter-frame interval is 50 milliseconds or less, even on fast, modern hardware. The faster-framerate animations at the right end of the row above fall farther and farther behind the others, if you use their broken browser.

Apparently, Microsoft regards this bug as a feature.

If you find other browsers that have problems, please let me know. I'd also like to hear of any versions of Microsoft's browser that actually work correctly. Please tell me the version of the operating system, as well as that of the browser, that you've tested.

I hear from Mac users that Safari does very well. However, the author of gifsicle points out that Safari also has some bugs in its gif-display code.

Which browser is this?

If you're working on an unfamiliar machine, you can learn what browser you're using at various websites, such as this one, or this one.


Copyright © 2012 Andrew T. Young

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