Format Reference

XviD

XviD is the name of a popular new video codec being developed as an open source project by volunteer programmers from all over the world. The format was created to offer a free alternative to other commercial video codecs, and despite being open source its quality and efficiency has made it one of the most popular video codecs online. While XviD still isn't as widely used as DivX, playback of XviD movies is usually supported in new DVD players nowadays.The XviD codec makes it possible to compress a full-length DVD-quality movie enough to fit on a single CD (might require 2 CDs depending on the length of the movie), while still maintaining the original image quality. Despite the fact that XviD movies offer higher quality video at smaller file sizes they take less time to encode than MPEG-2 due to the incredible compression technology. The video is usually combined with MP3 or AC3 audio to enable both high quality video and audio. These factors and the fact that the codec is distributed for free has contributed to the success of the format.

H.264

H.264, also known as MPEG-4 AVC (Advanced Video Coding), is a video compression standard that offers significantly greater compression than its predecessors. The standard is expected to offer up to twice the compression of the current MPEG-4 ASP (Advanced Simple Profile), in addition to improvements in perceptual quality. The H.264 standard can provide DVD-quality video at under 1 Mbps, and is considered promising for full-motion video over wireless, satellite, and ADSL Internet connections.

Xvid need less time to convert ,but H.264 has better quality and small size.