Proxy files are copies of raw video data, transcoded to a lower resolution and a codec that is optimized for editing. They are generally much smaller in file size, and demand less from your machine.
Proxy files are used in place of your raw video data when editing a project.
Once the project is complete, the raw video data is then re-linked, and the final product is rendered in its original quality.
By editing your entire project with a lighter codec and low-resolution video content, you avoid heavily taxing your machine. This will ensure smooth playback, even in an effect-heavy project.
Proxy files also have the added benefit of being smaller in file size, and thus more easily transferable. This is particularly helpful when working on a single project with multiple machines. The raw video content can be stored on a single drive, and the proxies can be copied to other devices throughout the editing process.
This is a fair criticism, particularly on very short projects that need to be edited quickly. In these situations, it may not be worth investing the time generating proxies.
However, on most other projects, your investment of time will almost always pay off – especially when working through multiple revisions.
If you are familiar with your editing machine, and understand what it is capable of handling, you’ll find it much easier to make the right judgement call on different projects.
Currently, both Final Cut Pro and Premiere offer built-in proxy generation.
This will allow you to automatically generate proxy files upon import. It will also allow you to easily flip back and forth between your raw video data and your proxy files, while editing.