Shortly after the introduction of Apple QuickTime, Intel responded with its Indeo Video Interactive (IVI or Indeo 4.0) codec. This format allows for scaleable software-only video playback. IVI can compress video symmetrically (in real time, larger file size) or asymmetrically (off-line, smaller file size, low data rates, highest quality). Compression times have been dramatically shortened by the new off-line Quick Compressor, which is up to 50 times faster than previous versions. The earlier Indeo 3.1 and 3.2 codecs typically managed 320×240 at 15 fps on Intel 486-based computer, and scaling the window resulted in a pixelated image. The current version is optimised for Pentium Pro and Pentium II processors, resulting in smooth 30 fps playback. Indeo delivers good quality on low-end Pentium-processor computers as well, employing special techniques for graceful scalability.

In contrast to QuickTime, which drops frames intentionally to accommodate slower computers, Indeo dynamically varies image quality according to processor power available during playback. The frame rate remains constant – with no dropped frames – instead trading off a degree of detail. Additionally, Indeo’s “Alternate Line Zoom-by-Two” doubles window size by horizontal pixel doubling, then drawing a row of black pixels in between each row. This smoothing technique minimises the pixelation associated with scaling the window. Other innovative features include “Transparency”, a compositing effect in which an object can be layered on top of video, just as a TV weatherman stands in front of a blue screen so that his image can be electronically cut and placed on top of a background layer, the weather map. Indeo’s sophisticated implementation includes compositing over moving backgrounds, moving objects (sprites) across frames, and more, comprising the “Interactive” features. Indeo is supported by Microsoft VfW and ActiveMovie.

 

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