Animated Portable Network Graphics
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| Animated Portable Network Graphics | |
|---|---|
 animated PNG featuring a bouncing ball (requires beta versions of common web browsers) |
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| File name extension | .png |
| Type of format | animated PNG |
| Extended from | PNG |
The Animated Portable Network Graphics (APNG) file format is an unofficial extension to the Portable Network Graphics (PNG) specification. It allows for animated PNG files that work similarly to animated GIF files, while retaining backward compatibility with non-animated PNG files. Its main purpose is said to be in GUI and XUL application usage, but open usage on the Web is also expected.[citation needed]
The first frame on an APNG file is stored as a normal PNG stream, and so most old PNG decoders will be able to display the first frame of an APNG file. The frame speed data and extra animation frames are stored in extra chunks (as provided for by the original PNG specification).
APNG competes with Multiple-image Network Graphics (MNG), a powerful format for bitmapped animations created by the same team as PNG. APNG's advantage is the smaller library size and compatibility with older PNG implementations.
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[edit] History
The APNG specification was created in 2004 by Stuart Parmenter and Vladimir Vukicevic of the Mozilla Corporation. APNG support was added to the ubiquitous libpng by a Seneca College student during the Google Summer of Code in 2006. Mozilla Firefox eventually added support for APNG in Firefox 3 trunk builds on 23 March 2007.[1]
The PNG group officially rejected APNG as an official extension on April 20, 2007.[2] There have been several subsequent proposals for a simple animated graphics format based on PNG using several different approaches.[3] Among the maintainers of the PNG and MNG formats, APNG was not received well for several reasons. MNG provides all the features APNG provides, but is not supported at all by PNG-only decoders. APNG uses a technically feasible solution for storing any frames except the first, but the majority of the PNG group thinks this conflicts with the purpose of the PNG format – which is to store a single image. APNG would be compatible to this vision with alterations to its signature and intended MIME type, but these would break the desired backwards compatibility.
[edit] Application support
- Mozilla Firefox as of version 3 alpha 3 (23 March 2007)[4]
- Opera as of version 9.5 (September 14, 2007)[5]
- KSquirrel as of version 0.7.2 (October 3, 2007)
- XnView as of version 1.92 (December 19, 2007)
[edit] References
[edit] External links
- The APNG specification at mozilla.org’s Wiki
- Mozilla's APNG Demo Site
- Animated PNG Portal Site
- Implementation work
- converter from Animated SVG to APNG as a Firefox extension
- APNG tests for browsers supporting APNG 1.0
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