Perian is a freeware, open source QuickTime® plug-in for Mac OSX that adds native playback support for many popular audio and video formats in QuickTime Multimedia Player. The support for following multimedia types are supported:

MS-MPEG4 v1, 2 and 3
DivX 3.11 alpha
DivX
XviD
3ivX
MPEG4 video
H.264
Sorenson H.263
Flash Screen Video
Truemotion VP6
WMV
VBR MP3
AAC
AC3 Audio

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