Audio Visual Design Guidelines

Encoders & Decoders

6 views November 19, 2019 aetm 0

Function

AV over IP encoders and decoders are hardware devices, software protocols or a combination of both, whose function is to encode/decode AV signals for transport as a digital data stream across a communications network using standard protocols. They offer a range of different resolutions, refresh rates and colour spaces. Some models support HDCP content, whilst others are not.

Hardware

Common hardware features of AV over IP codec devices are below, but will differ amongst manufacturers and product ranges:

Encoder (Transmit) Interfaces Decoder (Receive) Interfaces
HDMI Input HDMI Output
HDMI Loop Out
DisplayPort Input DisplayPort Output
Analogue Audio Input (Balanced and Unbalanced) Analogue Audio Output (Balanced)
RJ45 1GbE Ethernet (PoE)
LC or SC 10Gbps SFP+ Fibre
RS232 (For control of connected device)
Infrared (IR) (For control of connected device)
USB Interfaces (Media Storage, HID – Human Interface Device)
DC Power

 

Form-factor designed to be mounted in the following situations:

  • Behind display
  • On rack shelf
  • Underside of table
  • Some floor box models available
  • Modular card-based chassis models are also available from a variety of manufacturers

Common Software Features

Common software features found in hardware encoder and decoder endpoints include:

  • Encoders/decoders may be typically either:
    • Open standard codec (H.264, H.265, or Motion JPEG 2000)  may be compatible across various manufacturers; or
    • Proprietary codec requiring encoders and decoders to be from the same manufacturer, and same product range
  • Network latency (end-to-end network transit) 
    • no greater than 45ms for lip-synced content 
    • no greater than 250ms for any other content streamed within a room
    • When streams are viewed outside of the room, higher latencies may be suitable
  • Streams video signals with selectable resolution, refresh rates and colour space  up to and including 4K60 with 4:4:4 subsampling

Common control and management features of AV over IP hardware codecs:

  • Embedded web browser configuration interface (navigate to codec device IP address to access management pages)
  • Remote management features
  • Customisable network and security configuration
  • Device discovery via Bonjour protocols
  • IP Control
  • RS232 Control
  • Supports 802.1x Network Access Control

Additional software features (platform-dependent):

  • Decoder device may accept multiple video streams to display on-screen concurrently (Picture-in-Picture)
  • Flat panel display video wall image processing
  • AES67 audio over IP standard support
  • Audio de-embed from video stream (audio breakaway)
  • Audio embed into video stream
  • Dynamic text overlay

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