There’s a lot of confusion about the three different media types in Final Cut Pro X: native, optimized, and proxy.
Native media is the format shot by your camera. For example, AVCHD, H.264, DV, and HDV are all examples of native media formats.
Optimized media is always ProRes 422. When the “Optimize Media” checkbox is checked during import, FCP X transcodes, which is a fancy way of saying it “converts,” your media from its native format into Apple ProRes 422.
Proxy media is always Apple ProRes 422 Proxy. Proxy media creates a reasonably high-quality media file, but at about 1/4 the size of ProRes 422.
When you import media from either a file or camera, you have the ability to optimize it, or create proxy files.
You also have the ability to convert media after you’ve imported the files. Simply select the clips in the Event Browser that you want to transcode and select File > Transcode media.
Either way, here are your options:
What’s “reasonable image quality?” Generally, the higher the bit rate of the media, the better the image quality. For this reason, since ProRes 422 has a much higher bit rate than ProRes Proxy, the image quality is potentially better. This is especially true if you are doing color correction, green-screen keying, or lots of image manipulation. However, if you are simply capturing and editing consumer-grade camera images, without many effects, you may not see any quality difference at all between optimized and proxy media.
Creating proxies or optimized media always makes a copy of your camera source files. Both optimized and proxy media will have better performance than the camera native formats.
You can select one option, both, or none. Depending upon which options you select, you could have up to three copies of your media files stored on your system:
1. Camera native
Duplicate media files are not necessarily a bad thing and FCP X will track them properly; however, multiple copies do require more disk space.
Not all camera formats require optimizing. If the Optimize option is grayed out, it means that the camera format is already optimized and would not benefit if converted into ProRes 422. (DV and AVC-Intra are two examples of already-optimized media formats.)
NOTE: For the geeks among us, optimized formats are those that are stored in an I-frame format.
My general recommendation is to always optimize media. Purchasing an extra hard disk will more than pay for itself in the time you save during editing.
SWITCHING BETWEEN FILES
To switch between native, optimized, or proxy files in your Project go to the Final Cut Pro > Preferences > Playback tab.
Click the radio button for Proxy to edit using Proxy files.
Click the radio button for Original/Optimized to edit using anything else.
You can change this setting whenever you want, however, you can’t have a mix of some Proxy and some Optimized files in the same Project at the same time. Proxy and Optimized files are stored in different folders in the same Event folder.
(By the way, I thought whether you selected High Quality or Better Performance in this preference pop-up menu, your output quality will always be the same – high quality. However, see Jason’s comment below.)
Final Cut Pro X 10.2
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