Recently, I answered a question about how to use AVCHD files from a consumer video camera on a Mac. It can be really frustrating since these files are not native to the Mac. If you have the Leopard or Snow Leopard operating system and you use iMovie or Final Cut or Adobe Premier Pro, you can read the files natively.
But what about playing them with Quicktime, or cataloging with Expression Media? In these cases, you need to do some kind of conversion of the files. There are two basic ways to do it – transcode or rewrap.
When you transcode, you take the bundle of JPEGs that make up the movie and you actually remake them. This is a destructive process that degrades the image as the individual frame images are remade. (That’s an oversimplification, but you get the point).
In general, whenever you transcode, you want to keep the original as well as the converted files. Not only is transcoding destructive, but there is the possibility of some kind of transcoding error, where frames might get dropped, or some other glitch introduced to the sequence. This means you’ll be really increasing the storage needs, since you’ll need to save (and backup) both the original and the transcoded versions.
When you rewrap, you are basically taking all the JPEGs inside the movie file and putting a new wrapper around them (kind of like what a DNG does with raw file data). Since the individual images for each frame are not remade, there is no loss of visual quality. This also greatly reduces the possibility of any kind of dropped frames, etc.
Clipwrap ($50) can turn those pesky AVCHD files into quicktime-native files quickly and easily. If it reports a successful wrap, you’re pretty safe in tossing the original files. (Of course, to be safest, you’d want to watch the entire clip before tossing the original.)
Thanks to Richard Harrington who first talked me through this issue when I was dealing with my own camera.