Final Cut Express: About the "Codec could not be opened" message
Symptoms
If you create a Final Cut Express project on a computer with additional software and then move that project to another computer with Final Cut Express with a different configuration, your clips may appear with the message, "Codec could not be opened," in the Viewer or Canvas windows.
This can occur if the software on your computer does not enable the same media formats as the computer on which the project was created.
For example, if you begin working on an instructor's computer that has both Final Cut Express and Final Cut Studio, you'll be able to import video that is supported by the codecs that are present on that computer, such as ProRes 422 (which is included with Final Cut Studio, but not with Final Cut Express).
Following this example, when you import a clip that is in the ProRes 422 format, you will be able to add it to a Final Cut Express sequence while on your instructor's computer. The clip will require rendering, but it will work.
The issue can occur when you bring the project over to your computer, because Final Cut Express doesn't include the same media format support that is included with Final Cut Studio. The result is that your clips cannot be displayed. Instead, you'll see the message, "Codec could not be opened."
Products Affected
Final Cut Express
Resolution
If you move your Final Cut Express project from one computer to another, it's important to use only video codecs that will be supported in all cases. If the first computer has Final Cut Studio, or if it has third-party software that enables additional media codecs, you may not be able to use the same clips on your computer that you can on the other computer.
Formats supported by Final Cut Express 4 include those supported by QuickTime. As a rule of thumb, you can test a given media file by trying to open it in QuickTime Player on the computer where you will be editing. If the QuickTime movie file plays normally in QuickTime Player on that computer, it is likely to work in Final Cut Express on that computer, but may require rendering. If QuickTime Player cannot play the movie file, it may display a message saying that additional software is required. Such files will usually not be automatically supported in Final Cut Express.
For more information about codecs and video formats, refer to the Final Cut Express User Manual, available from the Help menu in Final Cut Express.