"codec missing or unavailable" error when importing media file in Adobe Premiere CC
AVI is just a container for a video format, and can contain videos encoded in different formats. The error you're seeing says that Adobe Premiere does not know how to process the video format that's within the AVI file.


First, you would have to find out (or know) the codec used for the video within the AVI file and then download and install the appropriate codec on your system.
To find out the codec for the file, examine it using a tool like QuickTime or VLC and see if you can use the Inspectors in these to get the video and audio codecs for your file.
If these two don't help, you would have to use a media information tool like MediaInspector or AviInfo on OS X or GSpot on Windows. Then search and install the codec for the file.


Here's some additional explanation and information from Adobe on "Troubleshoot file formats and codecs":


  Video-recording devices and video software applications encode files in a specific file format, such as AVI, QuickTime (MOV), and Windows Media (WMV). For a list of the file formats that Adobe Premiere Elements supports, search "Supported file formats in Adobe Premiere Elements " in the Adobe Knowledgebase.
  
  Some video file formats, including AVI and MOV, are container file formats. The data inside these container files is encoded according to a particular codec. Codecs are algorithms for compressing video and audio data. Many different codecs exist.
  
  For example, an AVI file can be encoded with the DV codec, a commercial codec (such as DivX), a Motion JPEG codec, among others. (Camcorders that record to miniDV tapes use the DV codec. Some still-image cameras use the Motion JPEG coded.)
  
  Adobe Premiere Elements sometimes cannot decode video files that were created with a poorly designed codec or a codec that is not installed on your computer.
  
  Knowing the format and, when applicable, the codec of the files you are working with helps you use these solutions. To gather this information, do one or more of the following tasks:
  
  
  Open the file in Apple QuickTime Player and choose Window > Show Movie Inspector.
  If the file is from a camcorder, camera, or other video-recording device, see the device's documentation, or locate the device's specifications on the manufacturer's website.
  Open the file in a third-party application that analyzes media files, such as MediaInfo or GSpot 2.70.