RMVB is a file format with a variable bitrate developed by RealNetworks. Actually it is an improved version of RM format. It gives greater bandwidth to videos that are difficult to compress. The extension keeps a high video definition. RMVB files are very popular in Asia and they are not supported by all popular players, so the easiest way to playback them is to convert them to another most common format.

XviD is a codec based on the MPEG-4 standard. The codec distorts colors but it has high definition in dynamic scenes. XviD is constantly updating because it is an open source codec and anyone who is interested can participate in the development of the program. Using XviD may be illegal in some countries because the compression methods used in MPEG-4 are patented.