Difference between H.264 and x264?
 

What is the difference between these two codecs? I'm always using H.264 when encoding something for youtube. Whether I'm using Final Cut Pro, Quicktime or MPEG Streamclip it's always H.264 for keeping file size low and best quality. I've read about this x264 and it even has it's own wiki page but I can't seem to understand what it does or what it would be used for.

Re: Difference between H.264 and x264?
 

x264 Encoder is an encoding engine that produces video in the H.264/AVC standard. Google it, there are pages out there

Re: Difference between H.264 and x264?
 

h.264 is not a single codec. It is a codec spec that is written by a committee that is now a standard. There are numerous implementations of h.264, Sony's, MainConcept's, Apple/QT's come to mind as distribution codecs. Within this standard there are many liberties one might take in designing a codec that still conforms to the spec, but satisfies particular purposes.

For example, alpha-channel transparency is part of the codec spec, but I have been unable to find a codec/encoder that supports it.

x264 is an h.264 codec *and* an encoder. It is open-source, and is one of the best h.264 codecs. The package includes a command-line encoder, which is quite acceptable in certain circles, but very opaque to the casual user.

x264 may be installed/configured in such a way as to give codec access to your favorite encoder, eg. there is a method for making x264 available in Apple Compressor. The latest Sorenson Squeeze includes x264. There is a very nice open-source freeware called Handbrake that provides a graphical user interface (GUI), and is one of the easiest and best ways to create video for web distribution.