Glossary - A Practical Guide to Video and Audio Compression - page 738

Topic Description

SheerVideo This is a lossless codec with a low compression ratio of about

2:1. It has limited availability and is only supported on Mac OS
X. For any portability that is required, the animation codec is
probably better suited.

SIF Source Image Format. Usually describes a TV standard that an

image was originally derived from.

Slice A sequential run of macroblocks in a frame of video. This is a

group of horizontally ordered blocks and never more than an
entire row with modern codecs.

SMPTE Society of Motion Picture and Television Engineers.

Sorenson 3 A codec originally shipped within Apple QuickTime. The codec

is now available independently and is also still available within
the QuickTime architecture. Sorenson version 3 is a codec that
produces good quality even when the bit rate is wound down
quite low. Artifacts are minimal at low data rates. File size and
bit rate gets large at high-quality settings. The bit rate
sometimes spikes when presented with video that is difficult to
encode. Sorenson 3 is a good general-purpose codec but H.264
will likely replace it in due course. Versions of Sorenson prior to
version 3 are legacy codecs.

Sorenson Spark This is the video codec used in Flash.

Betamax A tape format introduced for consumer use by Sony

Corporation. It delivered a good performance compared with
the rival JVC VHS system that dominated the market. Sony
evolved the cartridge format into a range of professional
formats known as Betacam and its derivatives.

Stream A single component, which can be received and then unpacked.

Streams may contain other streams multiplexed inside them.

Streaming server A server for delivering the packets that make a stream. They

must be delivered reliably and continuously at a rate that
averages out to be real time.

Sub-sampling Sampling an analog signal at larger intervals in order to reduce

the amount of data recorded. Unfortunately, the higher-
frequency information is lost at the source.

Systems layer The part of an MPEG standard that describes the containment of

the video and audio streams and the control of their playback.

T1 A very fast network link for connecting enterprises to the

Internet.