Why is my video so large? Final cut pro X

If you are rendering automatically 'as you go' (the default) the following may be helpful...

When editing, FCP 10.1.x does not throw away any previously rendered media when it is updated (so the update can be rapidly undone). This means that the size of the render files keeps growing. If you select an event (or a library) and choose File - Delete Generated Event (Library) Files you will get a window where you can select to Delete Generated Event (Library) Files. Check "Delete Render Files". Make sure "Unused Only" is selected (default). On clicking OK all the unused files will be immediately deleted and you will see the available free drive space grow considerably.

Geoff.

Without going into too much detail the reason is this: Video clips from a camera are strongly compressed so as to minimise file size on the camera card. For the same reason exported videos are normally saved in a form which is compressed. The problem is that in order to edit compressed files they must first be uncompressed which takes quite a lot of computing power and slows down the process. So what FCP does by default (this can be changed as described by Luis Sequeira1) is to convert all clips as they are imported into an uncompressed format (ProRes) which can be edited much quicker. It keeps them in this form until you you export the finished movie when it converts it to a compressed format. The downside of this is that the uncompressed format can be as much as 10 times larger than compressed ones. For most people the improved editing response speed is more important to them than needing more storage space.

As Luis has already indicated, is not really a good idea to store FCP media in the default system disk location (~/Movies) and most users keep it on a large (several TB size) external drive reserved just for this. More memory (at least 8 GB) also helps.

Geoff.

PS Ah I see Luis has responded while I was writing this - but I'll leave it on.

The size seems about right for ProRes. This is a very high quality family of codecs that is suitable for editing. It occupies a lot of drive space but is much easier to decode by your computer.

If you want to export a more manageable size movie, choose H264 as the codec in File->Share->Master File.

Also, note that for the most part you do NOT need to render. Many people keep background rendering off and only render manually those parts where playback is not smooth, because of the number of effects applied, for example.

You do NOT need to render before export, either.

For very little money, you can most likely improve your editing experience by:

1) adding more RAM and 2) using a fast external drive to contain your media an d libraries.

kschaff11 wrote:

I'm still curious why the file itself is still so large.

I told you why in my previous post, but let me ellaborate just a bit.

A video is composed of thousands of frames, each one composed of millions of pixels.

Say you have one minute of 1080p video, at 30fps. That is 1800 frames, each one containing nearly 2 million pixels. If each pixel were to use 4 bytes (32 bits, 8 for each color plus alpha channel), that would add up to 14GB - remember we are talking of one MINUTE of video!

Obviously this cannot be. Video has to be COMPRESSED. There exist many different compression and decompression methods (or "codecs", which is a moniker for compressor/decompressor).

H264 is one of the most common, and produces relatively small files. It compresses both spatially and temporally: it takes advantage of the fact that parts of the image (like a static background) may stay the same from one frame to the next. H264 is the basis of most common cameras, and is the video codec behind AVCHD. It is used for recording and publishing because of the small size, for both storage and transmission.

On the other hand, the more compression is applied the more math is involved and the more your processor has to calculate in order to reproduce the video.

So for editing a heavily compressed codec like H264 is not best. ProRes is the professional family of codecs that is behind FCP X. ProRes files can be like 10 times larger than their H264 counterparts. They retain more quality as they are edited, and are easier on the processor.

If you export a file meant to be viewed, not edited further, export as H264 and it may be 5GB instead of 55 (or it can be even smaller if you downsize or reduce bitrate).

But you may also export a master in ProRes for safekeeping, lest you need it somewhere down the road for another project.