Compressing Video Files

High-speed Internet and social media Web sites make sharing videos with friends and family much easier these days than ever. If you want to share more than a minute or so, or want to make them viewable on smart phones and reduce download times, though, it's always a good idea to make the file size as small as possible without losing too much quality. Compressing video files according to their content can make a huge difference.

Video compression

Without getting too technical, the video file format extension (.wmv, .avi, .mp4 etc.) will tell you which programs can open and run the file, but that's only half the story. These file formats are actually container formats, which comprise a video file and an audio file, each compacted according to a compression format, or codec. You don't need to know too much about these, just being aware that you can treat audio and video in your media files separately can create smaller files.

Video editing software

If your version of WindowsR didn't come with Movie Maker preinstalled, you can download it free from MicrosoftR. As well as being a basic media editor, it's a useful tool for compressing files. An alternative is the free version of NCH VideoPad Editor, or do an internet search for video editing software and download a few trial versions until you find one you like. Although we'll be looking at Windows Movie Maker and .wmv files, the principles are the same whichever software you use.

File preparation

First, get your native file into your video editing program. Usually this is a simple matter of connecting the device (camcorder etc.) to your computer and allowing your computer to copy the file into a folder on your hard drive, which you then open in Windows Movie Maker (WMM). Or, you can add files from within the software by using File> Import From Device.

Make a note of the dimensions of the original video. There's no point saving a video to a HD quality 1920 by 1080 pixels that was recorded at 640 by 480, as you'll just end up with a large file of blocky quality. Also note the frame rate, bit rate and audio quality. You can find these by right clicking on the file in Windows Explorer and clicking on Properties, then the Details tab.

Reduce File Size

With your file open, do the following to reduce file size and add compression to video files:

• Consider editing the video to a shorter length if possible.
• Decide on the dimensions of the video. If you're sharing online, 640 by 480 is usually high enough, though you can, at a push, go up to 854 by 480 for widescreen videos.
• Look at the audio quality. If the only sounds in the video are background noises, you can cut the audio bit rate right down without losing anything. If sound is important, keep the audio qualities near the original and save space compressing the video instead.
• If there is little movement on the video, you can reduce the frame rate without losing quality. If it's a fast action clip, you'll want to keep this as high as possible though.
• To change video and audio compression settings in WMM, click on the down arrow at the bottom of the Save Movie button, and click on Custom Settings.

Experiment with changing the bit rate on both sound and video until you achieve the smallest file size with the best quality. If you are uploading to YouTubeR or other social media sties, WMM has built in uploaders that are preset to give good results for each Web site.