Digital Television Compression

Because digital television is in greater numbers data intensive than analog television and would ask much more bandwidth for broadcasting, its appliance would be impractical except for the performance that digital data can be compressed. Nearly every one of digital video is compressed either because it is recorded or before it is broadcast. As through digital audio compression, there are sum of ~ units types of digital video compression: lossless and lossy.

Lossless compression, as the name implies, means that about compressing the video, and then decompressing it, the restored video has altogether the exact same data as the pattern. Lossless has the advantage that ~t one matter how many times it is compressed

and decoded, none of the original data is dissolute. The decompressed video has all the characteristic of the original. The limitation of lossless conciseness is that it cannot

save not remotely as much space as lossy condensation algorithms. Consequently, lossless video codecs (codec is some acronym for compression/decompression) such viewed like Huffyuv and Lossless MJPEG are not used approximately as much as lossy codecs

which compress further, and thus save besides storage space.

Lossy compression is the mould of video compression that 95% of everything video codecs use. This means that when they compress video and then decompress it, the decompressed video does not after what is stated have all the data of the primordial. Lossy codecs include MPEG-1, MPEG-2, MPEG-4, Quicktime, DV, Digital-S, RealVideo, Sorenson, Indeo, and Cinepak. Each of these loses more data when it compresses the model video. The objective of lossy compression is not to lose any given conditions that will be observable on the cover as a deteriorated image. None of the codecs achieves this vexillum completely, but some come close to it.

The pair main methods of lossy compression are called intra-build and interframe

compression. Intra-frame property that each frame of video premises is compressed

independently without regard to which is contained in any other constitute. MPEG is an intra-frame pressing together method that uses the familiar JPEG striking compression

found in computer graphics and attached the Internet to compress each compose.This

type of compression results in very

little loss of quality in the resemblance, but is limited

in the purport of compression possible.

Inter-frame pressing together exploits the fact that most of a television image is not moving all the time. Inter-construct codecs look at the preceding devise (and sometimes

the following frame) to see what has changed in the system they are compressing.

They then wrap closely only the changed parts of the reinvigorated frame and repeat the

unchanged gifts of the preceding frame to influence a complete picture for the next frame.