x264 is described as 'free software library for encoding video streams into the H.264/MPEG-4 AVC format' and is an app in the Video & Movies category. There are more than 10 alternatives to x264 for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is FFmpeg, which is both free and Open Source. Other great apps like x264 are QuickTime Player (Free), Video Transcoder (Free, Open Source), DivX (Freemium) and Subler (Free, Open Source).
FFmpeg is the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created. It supports the most obscure ancient formats up to the cutting edge.
Video Transcoder is an application which uses the open source program ffmpeg to transcode video files from one format to another. By selecting the video to process, details for the video are provided and the desired settings can be configured.
DivX doesn't need much of an introduction, as the product speaks for itself. A powerful player, converter and decoder, DivX offers you a handful of tools to assist you in your video playing and encoding endeavors.
Subler is a Mac OS X application that opens media containers, allows you to add or remove media tracks inside them, and then saves them out again. In the specialized language of the video world, Subler is a “transcoder” or “demuxer” depending on how you use it.
Voukoder is system wide video- and audio encoding service for Windows that improves your media encoding experience. It supports various encoders (both CPU and GPU based) and also provides a set of post processing filters.
optimizeVideo is just a simple wrapper around ffmpeg, but that saves a lot of guessing. It analyzes the contents of a target video file, and sets the conversion parameters according to Google standards.