WMM Book Cover


Windows Movie Maker

Understanding 'Preparing'

When an HD sized video clip is added to a project it is 'prepared', a process that takes some time.... too long for some users but OK with me. Movie Maker 2012 added an option to turn off the prepping process if you want.

Similarly, when you use the video stabilizing feature of Movie Maker 2012 it goes through the same kind of 'prepping' process.

It's a beneath-the-hood process worth understanding.

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Here's a screen snapshot showing what happens when a 1080 sized HD video clip is added to a project... for the first time. The file could by a wmv, mov, mts, etc... any clip that is high def.

The first frame of the clip shows in the storyboard of WMM, with a little clock icon on it. The popup note says '...preparing video for improved playback performance...'. It's not an option you can opt out of... just wait.

Preparing video

Let's explore it by following a batch of 5 video clips through the process...


First a tip or two.

The time it takes to 'prepare' the files varies with the file types, quality level, and the power of the computer being used.... on my 64 bit HP Pavilian laptop it's done in about real time. Figure 5 minutes for 5 minutes of footage.

My library of HD video clips are on external drives and the temporary wmv or MP4 files made by the 'preparing' process are in a folder of temp files on my computer's c: drive.

My HD clips are 1920x1080 pixels in resolution, the high end of high-def files, ones that all versions of Movie Maker either can't handle or has difficulty previewing smoothly. 'Preparing' the clips is done to make the editing process flow smoother.

The temp files are wmv or MP4 files of 640x360 pixels and found in the c:\Users\(PapaJohn)\AppData\Local\temp folder). They are of sufficient quality to do a number of things with, such as posting to a website. The temp files have automatically assigned file names.... it's easier to open them to see how they relate to the source files.

It would be great if, when I travel with my laptop and want to have another editing session with WMM, I could do it without having to bring the external drive. But I can't.

WMM checks the source files when you open a project and won't let you edit it without verifying the high quality MTS source files are accessible. If you look in the project file you'll find pointers to the original source files, not the temporary files.

I don't know what cross-references the originals and temp files.

If you use the same clip again in the same or a different project, and you still have the temporary wmv copy on your hard drive, it won't have to prep it again. Keep on eye on the size of the folder as it builds up over time. The temporary wmv or MP4 files won't be automatically removed.

5 video clips on an external drive

My HD camcorder saves files as HD1080 sized files with .MTS file extensions. Here are 5 selected ones in the sequence taken, looking at them with a general purpose file manager (Total Commander).

5 HD Sized Files on External Drive

the clips in Sony's PMB software

Here are the same clips, this time looking at them in Sony's PMB software that came with my camcorder... a great app for browsing them.

Here I've selected the 5 clips and opted to bring them into WMM, an option in the PMB menu.

Files in Sony PMB

PMB opens WMM which imports the 5 clips as a batch process.

WMM 'prepares' the clips

WMM Preparing Files

HD sized video clips of any file type are automatically 'prepped' by WMM immediately after being added to the project. It copies the files to lower quality wmv files to use in the editing process but uses the original files to maximize the quality of the saved movie.

You can see from the screen shot the files are not prepared in the same order they are on the hard drive.

You can add more clips to the project as the 'preparing' is happening. The HD sized video clips will be added to the prepping queue.

the lower quality clips

Here's a view of the 5 temporary lower quality wmv files made from the HD sized MTS files.

Temp Files