QuickTime is the built-in player for Mac OS, which has its own extension called .mov. Part of MPEG-4 and of AVI format can be supported by QuickTime, too. As for the format incompatible, you can't play videos in format like WMV, VOB, MPG, MP4 in QuickTime directly. Thus you need QuickTime Converter to solve the problem.
Here recommend two versions of QuickTime Converter—Video Converter for Mac users and Video Converter for Windows users. They can convert AVI, WMV, MP4 and other videos to QuickTime compatible format, and vice versa, as well as extract audios from QuickTime videos.
By default, QuickTime supports MOV file only. Thus you may encounter many situations of format incompatibility no matter you are a Mac user or a Windows user. Here are some of the situations you need QuickTime Converter for Mac/Windows, which can convert video to QuickTime in Mac/Windows and vice versa.
Convert AVI to QuickTime: If your AVI files are encoded with a codec that QuickTime can't recognize, like DivX, XviD, you'll need to convert AVI to MOV or other iOS and Mac OS compatible formats.
Convert WMV to QuickTime: Drag WMV files either downloaded from Internet or shared from others who have PCs to QuickTime, but find them incompatible for QuickTime.
Convert MP4 to QuickTime: Some MP4 files contain QuickTime-incompatible video codecs. You want to put these MP4 files in QuickTime.
Convert QuickTime to MP4: A common reason why we convert QuickTime MOV files to MP4 files is that the videos may be played on Apple TV, Blackberry, PDA, Smartphone or PSP, which can't support MOV format.
Convert QuickTime to WMP: Windows Media Player (WMP) natively supports formats like: asf, .avi, .dvr-ms, .m1v, .mp2, .mp2v, .mpg, .mpeg, .mpg, .mpv2, .wm, and .wmv. You need to share video from QuickTime with other friends who use the Windows System.
Different OSs have different versions of QuickTime Converter. For Mac users, turn to the tutorials of the best Video Converter for Mac.
However, for how to convert videos to QuickTime MOV file in Windows 8/7/XP/Vista, Windows users can go to Video Converter's guide.
Video formats: QuickTime Movie (.mov), MPEG-4 (.mp4, .m4v), MPEG-2 (OS X Lion or later), MPEG-1, 3GPP, 3GPP2, AVI, AVCHD (OS X Mountain Lion only), DV etc
Video codecs: MPEG-2 (OS X Lion or later), MPEG-4 (Part 2), H.264, H.263, H.261 etc.
Audio formats: iTunes Audio (.m4a, .m4b, .m4p), MP3, Core Audio (.caf), AIFF, AU, SD2, WAV, SND, AMR etc
Audio codecs: AAC (MPEG-4 Audio), HE-AAC, MP3, AMR Narrowband, Apple Lossless.
When the conversion of QuickTime converter is done, you can play the output videos in QuickTime, edit them in iMovie, Final Cut Pro, or put them on your iPad/iPod for playback whenever you like. You can also convert QuickTime MOV file to these video formats in the same way, just choose the target output format.