近期将MacBook Air的操作系统升级到10.8后，发现理论力学中的部分视频无法在PowerPoint中播放。这些视频不能用QuickTime播放，但可以用VLC正常播放。利用VLC检查发现这些视频的编码格式为“Microsoft Video 1(CRAM)”。
产生这个问题原因是曾在机器上为QuickTime安装了DivX组件。在Finder中选择Go | Go To Folder菜单项，在对话框中输入"/Library/QuickTime"，然后删除标记为DivX Decoder.component、DivX Enccoder.component以及在文件名中包含DivX 或3ivx的所有文件，并下载安装 Perian。
Perian aims to provide a single package for all your playback needs. It is a collection of QuickTime components incorporating several libraries:
• libavcodec, from the ffmpeg project, along with code from the old FFusion component:
• MS-MPEG4 v1 & v2
• DivX
• 3ivx
• H.264
• Flash Video
• Flash Screen Video
• On2 VP3, VP6, VP8
• H263I
• HuffYUV and ffvhuff
• Indeo 2, 3 & 5
• MPEG-1, 2 & 4 Video (in supported formats)
• Fraps (up to v4)
• Windows Media Audio v1 & v2
• Flash ADPCM
• Xiph Vorbis (in Matroska)
• MPEG Layer I and II audio
• DTS Coherent Acoustics audio
• Snow wavelet video
• DosBox video
• Nellymoser ASAO audio
• libavformat, from the ffmpeg project. along with AVIImporter.component:
• AVI file format
• FLV file format
• NUV file format
• libmatroska, along with matroska-qt.component:
• MKV file format
• Subtitles:
• (Advanced) SubStation Alpha
• SRT
• SAMI
• VobSub
• liba52, via A52Codec:
• AC3 audio
To use Perian, open the disk image, and double click on the Perian.prefPane icon. It will automatically install and update all of its components.