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(1) (Switched Virtual Circuit) A network connection that is established at the time the transmission is required and disconnected when the session is completed. SVCs are normally implemented in connection-oriented systems such as the analog telephone network and ATM networks. Contrast with PVC.

(2) (Scalable Video Coding) An extension to the Advanced Video Coding (AVC) standard to accommodate rendering devices with different processing capabilities and/or degraded transmission paths. SVC allows low-resolution formats to travel as subsets alongside the high-resolution video. The subsets may eliminate frames or contain reduced frame sizes or both. Rather than display high-resolution video poorly, SVC enables lesser-quality video to flow smoothly on low-bandwidth devices and channels. See H.264.

(3) (SuperVisor Call) A mainframe instruction that passes control to the operating system.


An ITU standard for compressing video based on MPEG-4 that is popular, especially for high-definition video such as Blu-ray. Taking advantage of today's high-speed chips, H.264 delivers MPEG-4 quality with a frame size up to four times greater. It can also provide MPEG-2 quality at a reduced data rate, requiring as little as one third the original bandwidth.

Advanced Video Coding (MPEG-4 AVC)
Formerly known as "H.26L" by the ITU, H.264 is also known as "MPEG-4 Part 10" by the ISO MPEG group, which jointly developed the codec. In addition, the H.264 enhancements are achieved using a large number of techniques dubbed "Advanced Video Coding" (AVC).

H.264 Versions (Profiles)
H.264 is organized in more than 20 versions known as "Profiles," for handling low-quality video to video with the very highest resolutions. These Profiles are defined within Baseline, Extended, Main and High categories that cover resolution, bit rates and subsampling (see chroma subsampling). See SVC, HEVC, H.263, H.323, WebM, MPEG and codec.

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