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Annex: Digital Video and Data Storage 277
Annex: Digital Video and Data Storage
Video Editing on the PC
Digital video processing with the PC is comparable to audio processing. The analog
medium that is video must first be digitized before it can be processed by the computer.
g functions quite similar to recording via a sound card. The signal
flow is measured in very short, regular intervals, and the values resulting from it can then be
processed by the computer. The accuracy of each individual measurement results in the
resolution, and the frequency of the measurements results in the frame rate. The more
precise and frequent the signal is measured, the higher the quality of the digitized video, but
also the higher demands on the capture performance and the required storage space. The
ndling makes much higher
demands upon the hardware if good image quality is required. In order to be able to
cess video files on today’s PCs, they must be compressed. Digital audio, on
MPEG Compression
MPEG means "Moving Picture Experts Group" and defines a workgroup which cooperates
erally, the graphic data rate of the digital video standard is 167 megabits per second,
which, when not compressed, requires a far higher storage capacity than a DVD can offer.
A one-sided DVD 5 with 4.7 GB storage capacity is enough for 4 Minutes. For this reason,
the available pictorial material must be effectively compressed – a function which is
achieved with the MPEG procedure.
This procedure is based on the simple fact that up to 96% of digital video data consists of
repetition and can be compressed without visible degradation of the pictorial quality.
Each MPEG compression is, however, a data reduction and as such connected with
information loss. If the video consists of very extensive details, or if the content changes
very fast, then the picture may blur (dependent on the strength of the compression and the
quality of the encoder).
Errors can also result from so-called compression artifacts such as small color defects or
at are too dark.
At average compression rates under 3 megabits per second it is probable that you will
notice reduced quality. At rates around 6 megabit per second the degradation in quality
becomes almost invisible.
Digital video processin
Windows standard format for video files is AVI (audio and video Interleaved).
Digitizing video adopts either the camera or the graphics card, a TV card (e.g. Miro PCTV),
or a video card (e.g. Fast AV Master). However, video ha
reasonably pro
the other hand only uses compression for saving storage space.
with the International Standards Organization (ISO) as well as the international Electro
Technical Commission (ETC) to develop standards for video and audio coding.
Gen
images th