NCast Presentation Recorder Reference Manual
14. Terms and Definitions
14.1. A
UDIO
AND
V
IDEO
T
ERMS
AND
D
EFINITIONS
A complete discussion of MPEG compression, Internet streaming, webcasting protocols and related
topics is beyond the scope of this document. Other sources cover this material in great detail. The
following are brief definitions of some of the terms used throughout this manual.
AAC – Advanced Audio Coding, a wideband audio encoding and compression algorithm.
Auto-detect – A capability to automatically sense if an input signal (graphics or video) is
present and to lock onto that signal without further manual intervention.
CIF - Describes an image or display surface with a resolution of 352x288 pixels.
DVI – Digital Visual Interface, a digital interface standard which provides for connection to
LCD panels and displays.
H.264 – A compression format that delivers very high quality video at low bit rates.
MPEG-4 Part 10 utilizes the H.264 codec for transmission.
HD-SDI, 3G-SDI – Hi-Def Serial Digital Interface, a coax based standard for digital video
signal interchange.
IETF – Internet Engineering Task Force, the standards body for Internet protocols.
ISO – International Standards Organization
Latency – The end-to-end time delay between a change in the source image and the
corresponding change in the remotely displayed image.
Line-Level – Sound level signals typically in the range of –10 dBu to +30 dBu.
Lip-sync – The synchronization of independent audio and video streams at a receiving
decoder so that the presentation is in the same time relationship as the source.
Mic-Level – Sound level signals typically in the range of –70 dBu to –30 dBu.
MPEG Compression – MPEG is an acronym for Motion Picture Experts Group, an
industry-wide committee which has defined a series of standards for the compression of
audio and video source material.
MTU – The maximum transmission unit is the maximum number of bytes permitted in a
transmitted packet.
Multicast – A family of computer transmission protocols where multiple receivers access a
single transmitted packet stream.
PIP – A picture-in-picture function overlays one video or graphics image with a reduced-
sized version of another video image.
Presentation Server – NCast's Open-Standards video and presentation content
management system and video-on-demand server.
REST - REpresentational State Transfer (
REST
) is a style of software architecture for
distributed systems such as the World Wide Web.
RFC – Request for Comments, an Internet protocol standard.
RTMP – Real-Time Messaging Protocol was initially a proprietary protocol developed by
Macromedia for streaming audio, video and data over the Internet, between a Flash
player and a server. Adopted by Adobe and YouTube, it is now widely used on the
internet for streaming video.
RTSP – Real-Time Streaming Protocol is an IETF approved protocol for control of real-
time streaming on the Internet.
NCast Corporation
Revision 1.0
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