以编程方式编码多媒体文件格式

Question

I'm always wondered where to find rules to encode known file formats, for example: .jpg, .png, .mpg programmatically. How to write these binary formats? Some years ago, when I surfed phpBB scripts, I found that they for example don't use any gd or imagemagick, they write it in binary way. Not only for php, but for other languages as well?

Answer 1

• The Wikipedia Article seems to have a pretty good rundown on the PNG format's internal structure
• The JPEG standard (PDF) - read the Wikipedia article on JPG as an introduction
• Here's a nice one for GIF: GIF spec and the official one (much more heavy reading): Gif89a

Video encoding is a whole different issue, and orders of magnitude more complex... Although I imagine one can already spend a lot of time understanding the JPEG format in depth.

Usually, looking up the desired format's article in Wikipedia will either give you the format definition, or a link to the specification.