DIGITAL VIDEO COMPRESSION
By Internet Video Gal in Video Editing, Video Production Tips
What It Means For Up-Loading and Viewing Video on the Web
By Lorraine Grula
Internet Video Gal
Does all the technical jargon about digital video drive you bonkers?
Read on for a common sense explanation of digital video compression.
What is Compression and why bother?
Without video compression, Internet video would simply not be possible. It’s that important. Video files are HUGE. Download times for raw, uncompressed video would be so high that no one would bother, even at broadband speeds.
Compression is the process of taking the huge file and knocking the file size down while preserving a decent picture. Compression works by first analyzing the complex and detailed video signal. Portions of the signal not noticeable to the human eye are dropped. Detail and resolution are lost, but hopefully not too much. Different compression methods select differing data to lose and this causes variable results.
Often, a video signal is compressed, then when opened and played, it is decompressed and some of the lost information is restored.
Codec
Codec is a term that combines the root words compression and decompression. What is compressed must be decompressed. To do so properly requires the machine reading the file be able to reverse the process used for compression. Hence the two go together like a lock and key and form the word codec.
Compatibility issues come up with editing software or playing devices if the compression and decompression methods are incompatible. This happens frequently and produces the joy known as the video maker’s headache. I don’t know any serious video maker who hasn’t struggled at one point with compression incompatibility.
Different software platforms and the file formats they produce differ, in part, by their codecs. So if incompatibility arises, it almost always can be traced back to codecs.
Rarely do you need to concern yourself with the specifics of which codec is being used when, but being aware of compatibility issues can help you slog through the video production process whenever the inevitable problems arise.
Here on this blog you will find more digital video glossary terms and file format definitions.
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