.mov or .mp4 - is .mov worth the extra size?

When you delete the iMovie project and event, do you delete it in iMovie by clicking to delete the project (on the project menu page) then go to the media page and delete the event? I don't see a trash, so does it permanently delete it?

You are better off with the .mov files which are in the Apple Intermediate Codec.

H.264 (MP4) and AVCHD (.mts) both use Group of Pictures compression. In this compression scheme, there is one full frame for every (say) 24 frames of video. The remaining frames are partial frames that contain info like what has changed since the previous frame, direction of motion, etc. Obviously, this is not good for editing, because if you edit out the full frame, the remaining frames are useless. So before editing or sharing, all these partial frames have to be resolved into full frames.

Apple Intermediate Codec is a full frame codec. Each frame has some compression, like the full frames in h.264, but all frames are full and they are independent of each other. You can cut wherever you like, and you can apply slow motion without worrying about where you start.

In Final Cut Pro X, you would use ProRes 422, another full frame codec.

You should expect Apple Intermediate Codec to be about 10X larger than the equivalent h.264 clip.

So to recap, Apple Intermediate Codec and ProRes 422 are excellent ediiting codecs. AVCHD and h.264 are excellent delivery codecs for playback. So you want to edit your movie in AIC, then share it as h.264 for use on the web, or on your iPhone or TV.

In consumer video, you are never dealing with the equivalent of Camera RAW. Everything is compressed.

For uncompressed video, think of a live sporting event where there are 5 refrigerated trucks in the parking lot with the equipment needed to process the uncompressed video in real time. For Apple Intermediate Codec, you might see a ten times files size increase over a highly compressed format like AVCHD or h,264. However, with uncompressed video, you would see another 10 to 20x file size increase over the Apple Intermediate Codec file. So in your case, it would be about 100x larger than your AVCHD file. Your camera will not shoot uncompressed video, so this is all academic, but obviously, you would need a very powerful computer, you would need a large and fast array of disk drives arranged in a RAID, and you would need professional editing software like FInal Cut Pro. In practice, nobody uses uncompressed video except live TV, because in that format, they do not have the luxury of time for the compression. They compress at the end when it goes over the air as MPEG2.

When you are talking about converting a group of pictures compression to an I-frame codec, think of it this way.

Imagine you have a video of a duck flying across the sky. A lot of the motion is predictable. You are panning across the horizon at a pretty constant rate. The duck is pretty much the same, except its wings are beating up and down. So you could take a picture of the duck in flight, and then code some information that says, OK take the previous frame and move the background to the right, and make the wings go up a little bit. That takes up a lot less space than storing that information as a full frame. That is how group of pictures works.

When you convert the GOP codec to an I-frame codec like Apple Intermediate Codec, you are resolving those instructions so that each frame is a full frame. Apple INtermediate Codec and DV are two examples of codecs where every frame is compressed, but each frame is independent of all the frames around it.

To further muddy the water, your instinct that the camera copy is somehow better than something that you convert it to is a good instinct. This is because the first generation (what the camera sees) is about as good as it gets. Subsequent generations always have the risk of some loss of information. So I would recommend that you always keep the first generation copy. iMovie makes it easy to do this from the import screen by creating a camera archive.

One example of this is that when you convert your AVCHD to Apple Intermediate Codec, the AIC uses a 4:2:0 colorspace. Lets say that later on you wanted to edit in Final Cut Pro, where you have access to the ProRes 422 codec, which uses a 4:2:2 colorspace. I will not go into the technical differences between these, except to see that having more bits to contain color information is a good thing. And by having the first generation copy, you can convert to ProRes 422 directly, which is incrememtally better than converting from AVCHD to AIC and then converting to ProRes (which leaves some bits on the table).

To answer your second question, your workflow really depends on how you will use the footage.

My workflow is:

1) On the iMovie import screen, I create a Camera Archive. This makes an exact duplicate of the camera information.

2) I then use the Camera Archive copy to import the clips into an iMovie Event. When all is well, I will reformat the SDHC card on the camera so I can have a fresh card for the next shoot.

3) I edit a movie and export as h.264 through the Share menu.

4) I have the iMovie Projects automatically backed up through time machine and offsite (through the internet).

5) I back up the camera archive files through time machine and offsite through the internet.

6) I do not backup the Event files, because they are large and I can recreate them from the camera archive files.

7) I usually keep my event files, mainly for convenience if I want to do additional edits on a project, or if I want to use the clips in a new project. And yes, you need a lot of hard drives for this. However, if you rarely want to reedit or reuse clips once you have finshed a project, then you can delete your events. You can always create a new project by importing your camera archives again.

8) Of course I always keep the finished movies as well.

A project file should be quite small (with one exception). A project contains a text file that contains the instructions for creating your project. This file is in hexadecimal and is quite small.

However, the project file has another role that can make it large. Since iMovie can now make 1080P movies, this can be noticable.

When you SHARE your movie as SHARE/iTUNES or SHARE/Media Browser or FILE/FINALIZE PROJECT or SHARE/YOUTUBE, (maybe some others), it will render a copy in the sizes you specify and place them in the project package. The copy that is stored in the project package is the "Media Browser" copy. This enables you to use the finished movie in other apps such as iDVD, GarageBand, Pages, Keynote, iWeb, Micorsoft Word, Microsoft Powerpoint, etc from the Media Browser that is embedded in those apps. If a Media Browser copy exists, than you can share instantly to iTunes, YouTube, etc. because it does not have to take the time to render.

You can see these files. Go to the FINDER, in Movies/iMovie Projects on your startup drive, or on iMovie Projects at the top level of an external drive. Right-click on your project name, and select SHOW PACKAGE CONTENTS. You will see that the Project is really a package containing a group of folders. Go to the Movies folder in the package and you will see the finished movies in the media browser. Other large files could potentially be in there, too. For example, if you record a Voiceover, that goes in the project package.

As I mentioned, this can get to be a big use of space, especially with 1080P files. Also, if you create a copy that is stored in iTunes so you can view it on iTunes or Apple TV or iPad or iPhone, than now you have that copy plus the Media Browser copy. You could even get three copies, if you have iTunes set up to automatically import new files into iTunes. You will have the Media Browser copy, a copy in <User>/Movies/iMovie Sharing/ and a third copy that is imported into the iTunes Library in <user>/Music/iTunes/iTunesMusic/Movies. (iTunes Music may be called iTunes Media or something else on newer installations of iTunes.)

When you edit a project that already has been shared to the Media Browser, iMovie will warn you that you are changing a previously shared project. If you say OK, the Media Browser copies are immediately deleted to make room for the new copies that will be made when you SHARE after the edits.

You can always delete the Media Browser copies if you do not want them. As long as you keep your Events, you can always make more. I generally keep them for convenience. However, I have stopped automatically importing the files into iTunes so I don't have three copies. The good thing about the iTunes copy (also for SHARE/MOVIE or SHARE/EXPORT TO QUICKTIME is that these copies are permanent. You cannot accidentally delete them by editing your project.

- Can I delete the rendered movie files within them without problems? I mean: I have the exported files! Why would I want to have two files, when a project is done?

You can delete them if you like.

- Is it rightly understood, that iMovie will automatically render a new movie in the background if I open up the project again?

No it will not render in the background. To render it again, you use the Share menu. iMovie only renders when you share. Final Cut Pro X, on the other hand, renders in the background.

- finally: Is there a way to store projects on a secondary drive, or can iMovie only store Events and Archives on secondary disks?

Yes, you can move projects to secondary disks. Move them from within iMovie, just like you would move an Event. Use Command-Drag to move or Drag to copy.

Empty the trash to get your space back.

If you export as QuickTime movie, you can change the settings any way you want. So there is no need to store in the Media Browser, since you can choose settings that will not work in the Media Browser. (I'm guessing)

Export as Final Cut XML will export a text file that will give FInal Cut Pro your edit decisions, for people who want to do a rough cut in iMovie, and then do a finished movie in FCP. Not many people use this feature. With the new FCPX, you can open iMovie Projects directly in FCP without going through the step of creating XML. So you really only would use this if you wanted to use FCP 7.

For SHARE/EXPORT MOVIE (or Command E), iMovie will export in the sizes you choose in certain settings that make a good tradeoff between size and quality. The movies will be in the h.264 codec. They can be .m4v or .mov depending on the size. You can view the settings for codec, bit rate, approximate file size, and frames per second by hovering you cursor over the i at the right hand side of the varios size options.

For SHARE/EXPORT USING QUICKTIME you can customize settings, change codecs for both audio and video, change bit rates, etc. in many different ways. Some people will use this to export as AIC to use in another project. AIC keeps it in high quality. For standard def, you might export as DV. Some people use this to export the sound track with no video. (Sound to AIFF). Some people tweak the h.264 settings to try to keep close to the same quality with a smaller file size, particularly if it will be downloaded a million times from a server on the web. Then size matters a lot. It is unlikely you would get better quality by tweaking the settings, but if you would like to try, that is fine. You could also change containers. YOu could choose the MOV container, an MP4 container, etc.

I'm really green when it comes to this stuff so I'm having a hard time following...I apologize.

I've been using iMovie to import my camcorder movies. It occured to me lately that it takes up a ton of space. I also found the .mts file somehow of each video (it must save dupicates automatically). My question is, can I get rid of the .mov file and keep the .mts file and someday if I want to use iMovie to make a project, convert the files back to .mov?

I've reached the max memory on my laptop and external and need to start getting rid of stuff....or get a new external.

Here is what I do. My main goals are:

1. To have a complete and reliable archive of all home movies I have ever shot with my AVCHD camcorder;

2. To have easy access to individual edited home movies for playback on my TV and other devices.

When I shoot with my camcorder, I try to not shoot indiscriminately. Still, I like the ability to edit the final home movie for viewing. My complete archive is structured so that every time I fill up my SD card, I copy everything into a folder on an external hard disk (and make one more copy on another external drive, as a backup, just in case)

When I want to create watchable videos from any specific event from any of those SD card folders, I use iMovie (or Final Cut Pro X) and import that video. I edit, then share/export into a full-HD (1080p), high quality (but not ProRes) video in MP4 container, and put it into a folder of finished videos (for playback). When the edit is complete and the exported video is in its folder, I delete the iMovie project and the event folder with all of the imported files. The originals are still in the archive, and if I ever need to edit them again, I just create a new event folder and import again. That way, I maximise space saving by getting rid of any unnecessary duplicate files.

The bottom line is that all my original camcorder stuff is archived on an external hard drive, and all the edited home movies that are ready for watching are in their own folder, and if I need any of them elsewhere, I simply copy (via AirDrop, WeTransfer, DropBox, or a USB flash drive). For most home-bound viewing, they can be streamed directly from my iMac (via AppleTV).