Post Production: Compress This! Squeeze That!
In case you haven’t heard, video files can take up a ton of space.
Depending on how long it is, an uncompressed (or raw) version of your video can take up anywhere between one to 100 gigs of storage space on a hard drive. Space like that is usually a hot commodity, and the time needed to transfer files that large between computers/clients is even hotter. And forget about putting a video that large on the web. Only the most patient (read: crazy) viewers will stick around long enough to watch your video if its intended to be watched in its uncompressed form from the web.
So how do you get a high quality version of your video in a size small enough to be passed around the office and viewed off the web? If you guessed, “Compress it” then you did an excellent job of remembering the title to this article. But what exactly goes into compressing a video?
Because of the sheer amount of space needed, video must be compressed (or squeezed) to a smaller, more manageable size. This is where video codecs come into play. Codecs are the technical nuts and bolts behind the compression of your video (some common examples are the Window’s Media File, or .wmv and the Quicktime friendly H.264 codecs). In order to achieve its smaller size some sacrifices need to be made. The most notable loss in compression is often times the quality.
We’ve all seen examples of terrible compression techniques online (case in point: 75 percent of all videos found on YouTube.) A bad compression loses a large visually noticeable amount of quality and often times leaves artifacts and misplaced pixels floating in the video.
An example of an acceptable amount of quality loss would be most every DVD in your collection. The mpeg-2 format used to compress feature films onto a disc leaves us with a file 15-30 times smaller than the original with an arguably high picture quality. Blu-Ray video takes this to the next level by giving us a similar compression type while leaving the file closer in size and quality to the original raw file.
In order to make your video mobile via the web or on handheld devices it is necessary to squish it down into a much more manageable size. Depending on the method of final delivery and venue for viewing the video, consideration needs to be given to both size and quality. A good compression should always offer a perfect balance and present your video in such a way that it will be remembered not for the specs of its codec, but for the strength of its content.
