Monday, December 21, 2009

An Overview of Video Digital Compression

As customers continue to demand a higher quality production, the demand for compressing that production onto DVD’s, CD’s, and streaming onto the Internet becomes more of consideration than ever before. TV screens, computer monitors, and even cell phone screens have exploded in size over the last five to seven years. Filling those screens with high quality picture and sound can be an expensive process, but with modern-day compression methods, the process has become more manageable and more affordable.

The goal of compression is to shrink the digital video file down to a smaller size without compromising quality or frame size. When it’s time to view the video, a decompression (expanding) process must take place. A crude analogy to compression/decompression is a fluffy down comforter, which is placed into a plastic bag and vacuuming sealed. It’s easy to store, transport and when time to use it, simply open the bag and allow the comforter to return to it’s normal size. Another example is how iPod’s® can store days of music on a single unit.

Two basic types of compressions, or “codec” exist: lossy and non-lossy, or lossless. Lossy compression types lose quality, and data during the process, while Lossless, or non-lossy compression types retain quality, but successfully reduce the amount of data needed to view it.

Often times, videos are compression with an incorrect codec for the application. Pay close attention next time an online video is watched. Occasionally, while the video is playing, there are horizontal lines visible during playback. This is an example of using the incorrect codec for online streaming. Many others exist, but the scope of this post is to make aware of the countless different available compression processes.

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