Friday, January 19, 2007

Filmmaking and the Internet

Short films are too big for the internet and need to be squashed right down to make the process of watching more practical. Until both connections and cables for the majority of users have improved, this is the only viable way of using the internet for video.

What’s a codec?

Codecs are all designed to work on two fronts: temporal and spatial y of using the internet for vidcompression.the only viable way of using the internet Tjay TtTta That means they both compress the picture in terms of the amount of information used, but do this in different ways. Beyond this, there are other ways to compress further, by reducing colour quality, audio, pixel rate or frame rate.

Within these two formats, codecs are found in either hardware or software form. Hardware codecs are fast and more efficient but more expensive, and require that the receiver of the images has the same codec device. Software codecs do not have the same quality as hardware versions but most are available free on the Internet, and are more widely used on editing programs.

There are two ways of compressing a film. Here’s how it works:

  1. Temporal compression: Temporal compression takes out lots of information that you don’t miss by comparing the individual pixels in a frame-for example, if a frame looks almost the same as the last, perhaps with the same background colour, it recognizes this and hangs on to only those bits of information that differ from what was in the first frame, called the key frame. All other frames after the key frame it names "delta frames" and only starts a new key frame when the scene changes significantly. In this way, it manages to remove much information and reduce the overall file size.
  2. Spatial compression: Spatial compression works differently: it still looks for data that appears more than once but instead of studying each pixel, it divides up the whole picture into blocks of pixels. It looks for patterns of repetition within these blocks, enabling it to map them using much less data. Pushed too far this can result in blocky, jagged looking images but it remains a powerful, if unsophisticated, compression solution.
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