Microsoft AVI and ASF
AVI (Audio Video Interleave) and ASF (Advanced Streaming Format) are container formats like QuickTimes .mov files. That is they can contain video and audio encoded in many different ways. WMV is one of the common methods for encoding video used in AVI, and WMA for encoding audio. Both can be packaged as an AVI or ASF file.
Some AVI files (uncompressed or compressed with Cinepak, BMP or DV) can be played by QuickTime Player. Others may require a codec for playback. One example of an extra codec is:3ivxD4 at VersionTracker. It is free for testing purposes and handles most MPEG-4 variants including DivX 3,4 and 5, Apple MPEG-4, Philips MPEG-4 and XviD.
More about converting WMV to QickTime