[Mediawiki-l] Animated Gifs

Tim Starling tstarling at wikimedia.org
Sun Oct 24 19:40:36 UTC 2010


On 22/10/10 17:35, Dan Nessett wrote:
> We are upgrading to 1.16. One of the things we would like to do is 
> support animated gifs. Unfortunately, there is a surfeit of information 
> about this issue, but nothing I have read so far gives a clear guideline 
> how to go about providing such support. The history of this issue is 
> found in at least the following places:
> 
> A Village Pump thread:
> 
> http://commons.wikimedia.org/wiki/Commons:Graphics_village_pump/GIF_thread
> 
> Some bug tickets, specifically:
> 
> https://bugzilla.wikimedia.org/show_bug.cgi?id=22041

That is a Wikimedia sysadmin issue and does not apply to other
installations.

> https://bugzilla.wikimedia.org/show_bug.cgi?id=23063
> https://bugzilla.wikimedia.org/show_bug.cgi?id=23063
> 
> While the first ticket is marked resolved/fixed, the latter two (which 
> cover the same or at least a very similar issue) are marked new. The last 
> entry in the 3rd bug ticket is dated 2010-05-08.

That is two copies of the same link. See below for a discussion of it.

> So, I wonder if anyone is able (and is willing) to supply the following 
> information:
> 
> + The version of imagemagick that we should install for animated gif 
> support.
> 
> + Whether 1.16.0 is sufficient for non-buggy animated gif support.
> 
> + Is there any configuration required for animated gif support, other 
> than setting $wgMaxAnimatedGifArea?
> 
> + Is there anything else we need to do to support animated gifs?

MediaWiki and ImageMagick have both supported animated GIFs since
forever. You don't need any special version.

The recent problems with animated GIFs at Wikimedia were related to
changing usage patterns, specifically an increasing tendency to
convert large videos into animated GIF format. ImageMagick handles
large animated GIFs in a very inefficient way. This led to several new
resource limit features being developed, in order to provide more
useful and stable error messages, as opposed to letting ImageMagick
hit a memory or time limit.

If your users stick to using animated GIF in its traditional
applications, e.g. MySpace-style sparkling flourishes and looping
diagram animations, then you should have no trouble. If your users
wish to convert hours of MPEG video to animated GIF format and have it
scaled by your servers, then your choice of MediaWiki version and
resource limit configuration will determine what sort of error message
the users see. Ideally, this should be an informative "image too
large" error, rather than a browser timeout because the server has
gone into swap and died.

-- Tim Starling




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