What Is Video Compression?

Understanding Lossy and Lossless Video Compression

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Videos take up a lot of space—just how much varies widely depending on the video format, the resolution and the number of frames per second you select. Uncompressed 1080 HD video footage takes up about 10.5 GB of space per minute of video. If you use a smartphone to shoot your video, 1080p footage takes up 130 MB per minute of footage, while 4K video takes up 375 MB of space for each minute film. Because it takes up so much space, the video must be compressed before it is put on the web.

“Compressed” just means that the information is packed into a smaller space. There are two kinds of compression: lossy and lossless.

Lossy Compression

Lossy compression means that the compressed file has fewer data in it than the original file. In some cases, this translates to lower quality files, because information has been “lost,” hence the name. However, you can lose a relatively large amount of data before you start to notice a difference. Lossy compression makes up for the loss in quality by producing comparatively small files. For example, DVDs are compressed using the MPEG-2 format, which can make files 15 to 30 times smaller, but viewers still tend to perceive DVDs as having high-quality pictures.

Most video that is uploaded to the internet uses lossy compression to keep the file size small while delivering a relatively high-quality product.

Lossless Compression

Lossless compression is exactly what it sounds like, compression where none of the information is lost.

This is not nearly as useful as lossy compression because files often end up being the same size as they were before compression. This may seem pointless, as reducing the file size is the primary goal of compression. However, if the file size is not an issue, using lossless compression results in a perfect-quality picture.

For example, a video editor transferring files from one computer to another using a hard drive might choose to use lossless compression to preserve quality while he is working.

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