Extron electronics SMP 300 Series User Manual page 171

Channel — A group of inputs that the encoder treats as a single input because only one
input in the group can be selected and active at a time. One video input and one audio input
signal are selected per channel and passed on to the encoder. For the SMP 352 there are
two input channels:
• Channel A groups inputs 1 (HDMI) and 2 (HDMI) together.
Channel B groups inputs 3 (component or composite video), 4 (HDMI), and
•
5 (3G/HD/SDI) together.
In composite mode, depending on layout configuration, one or both channels can be
encoded (together with a background image and metadata) and incorporated into the
output stream.
Codec — (1) Coder/decoder: A device that converts analog video and audio signals into a
digital format for transmission over telecommunications facilities and also converts received
digital signals back into analog format. It may also dial up the connection, like a modem for
teleconferencing. (2) Compressor/decompressor: Codecs can be implemented in software,
hardware, or a combination of both.
Composite encoding mode — The SMP 300 Series mode that signals from channels A
and B are combined into one archive stream (forming a single recording). This is the only
mode available in the SMP 351 and SMP 351 3G‑SDI.
Composite encoding is the alternative to dual channel encoding mode signals from channel
A and signals from channel B are encoded to separate archive streams (and, therefore,
separate recordings), each with its own settings. SMP 352 Series models and SMP 351
Series models with LinkLicense offer both dual channel encoding and composite encoding.
Compression — The art and science of reducing the amount of data required to represent
a picture or a stream of pictures and sound before sending or storing it. Compression
systems are designed to eliminate redundant or repeated information to the desired data
level while allowing the original information to be reproduced to the desired quality.
Confidence stream — The encoding stream used for video previews, as in the AV
Controls panel, and also for streaming. For composite encoding mode, signals for the
confidence stream are encoded at or below the resolution or refresh rate of the archive
encoding stream. The confidence stream uses the same audio settings as the archive
stream, but the video encoding differs.
Constant Bit Rate (CBR) — Constant bit rate encoding means that the rate at which
codec output data is consumed is constant. CBR is useful for streaming multimedia content
on data communication channels which operate more efficiently or require the bit rate to
remain within a tight tolerance. Typically the constant bit rate is created by stuffing bits into a
variable bit rate signal which has a defined peak or maximum limit.
Constrained Variable Bit Rate (CVBR) — This scheme is similar to
(VBR), (see page 169) but sets a maximum allowed bit rate that the encoder cannot
exceed.
Darwin Streaming Server (DSS) — Darwin Streaming Server is software developed by
Apple that provides a high performance media streaming server for delivering content.
The software is used to simultaneously stream to a broad range of screens and devices
(including computers, televisions, smartphones, and tablets).
Data bits — The number of bits used to represent one character of data. Data bits can be
7, 8, or 16, but most serial devices use 8 bits for ASCII characters.
DB ID — DB ID is the database identification number of a scheduled recording event. The
number appears in the event details within the Scheduled Events page.
To determine the event ID for a recording event, click on the Scheduled Events tab, locate
and click on the event in the calendar. The ID number appears in the Event Details dialog
box. Troubleshooting logs can be sorted or filtered by the event ID number.
Variable Bit Rate
SMP 300 Series • Glossary 163