Introduction

The page explains the function of a video encoder, and how it is integrated into a Witness system. 

Contents

Overview

A video encoder integrates an analogue CCTV system with a network video system. If your system uses analogue cameras, you must use an Axis Video Encoder for their video feeds to be supported in Witness. 

Purpose

• "A video encoder integrates an analogue CCTV system with a network video system, prolonging the operability of legacy systems. Encoders contain a compression chip and an operating system that converts incoming analog video into digital video. The digitized signal can then be transmitted and recorded over the network for easier accessibility and viewing. Furthermore, encoders provide analog CCTV camera systems with many features and functionalities otherwise only associated with IP-based systems, such as PTZ control."

• "If the video encoder supports Power over Ethernet (PoE), it can receive power through the same cable used for data transmission, providing substantial savings by the exclusion of power cables."

• "In terms of image quality, video encoders provide image fine-tuning, as well as aspect ratio correction that ensures that images do not appear distorted when viewed on a PC screen. High-performance video encoders provide full frame rate (30 fps in NTSC, 25 fps in PAL) in all resolutions for all video channels. Furthermore, unlike their analog counterparts, digital images retain their quality regardless of the distance travelled."

• "Video encoders use universally accepted compression standards such as Motion JPEG or H.264, enabling savings in bandwidth and storage. Using standards also means that operators avoid the risk of being stuck with a proprietary technique. "

• "Edge storage allows network video products, such as encoders, to store recordings locally on an SD (Secure Digital) memory card, or similar. This can be used as a complement to central storage or as a backup when the central system is not available. The system even allows missing video clips during network disruptions or central system maintenance to later be retrieved from the camera/encoder and merged with the central storage, ensuring uninterrupted and complete video recordings. Furthermore, video encoders create a more future-proof video surveillance system that allows users to also add network cameras and experience all the benefits of a network video system, including highresolution video with progressive scan, megapixel and HDTV image quality."

System Design

Open

Telemetry 

Pelco-D is a PTZ (Pan/Tilt/Zoom) camera control protocol used by analogue CCTV systems. This is the protocol Witness employs in order to manipulate the PTZ of an analogue, as long as the video encoder has a serial data connector. For example, the Axis M7011 has two 2-pin terminal blocks for RS485/RS422 serial interface used to control pan-tilt devices.

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