Audio Visual Design Guidelines

AV over IP

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Introduction

This chapter covers the primary components, common features, and best practices for planning, designing, and deploying AV over IP.

AV over IP is a method of transmitting (encoding), receiving (decoding) AV signals and routing the content as a data stream via IP network connections. This routing method functions much like a standard AV matrix switcher, with improved flexibility and scalability afforded by enterprise network switching and routing.

 

Scope of this Chapter

This chapter focuses on the technology and key relationships required to deliver low latency transmission of AV data over IP networks for commercial AV integrated technology. Transmitted AV data includes the following data types:

  • Video
  • Audio
  • Control
  • USB data:
    • Keyboard & mouse data
    • Camera & microphone data
    • File transfer data

Wireless presentation, and IPTV are outside the scope of this document.

Glossary of Terms

Term Definition
Air-gapped A network security measure employed to ensure that a network switch is physically isolated from all other network switches
Application Programming Interface (API) A sets of functions and protocols through which software may interact with an application,  AV system component, third-party software, or sub-system.
AV System A multimedia presentation system for video and audio presentations
AV Audiovisual (AV) encompasses the integrated devices for managing the routing, processing, and presentation of video and audio content. It may also include associated AV network data streams, user control interfaces, automation processes and integrations with other systems, to name a few.
Bitrate;

Data rate

Relating to digital devices and the transmission of data streams, bitrate is the number of data bits that are transferred per second
Broadcast A network message transmitted to all connected devices on the same subnet as the sender device
Codec A codec within the contet of AV, is a physical electronic circuit or a software method of compressing and decompressing video data.The word “Codec” is sometimes used to refer to a hardware or software encoder/decoder system; the word is  a portmento of Code-Decode.
DHCP The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on IP networks whereby a DHCP server dynamically assigns and manages IP addresses and other network configuration parameters to each device on a network so they can communicate with other IP networks.
Encoder/Decoder Hardware or software designed to encode and/or decode a digital data stream. An encoder is used to encode a video signal so it may be streamed or saved as a video file. A decoder is used to decode a video file or incoming data stream so that it may be viewed or stored on a device 
HDCP High-bandwidth Digital Content Protection (HDCP) is a form of digital copy protection developed by Intel Corporation[1] to prevent copying of digital audio & video content as it travels across connections. Types of connections include DisplayPort (DP), Digital Visual Interface (DVI), and High-Definition Multimedia Interface (HDMI)
HID Human Interface Device is a peripheral that connects to a computer to allow a user to interact and provide input. Examples include a keyboard, mouse, touchscreen etc.
ICT Architecture Information and communications technology architecture encompasses the computers,servers, security, phone systems, and network switching and routing for an organisation’s network
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association, formed in 1963 from the amalgamation of the American Institute of Electrical Engineers and the Institute of Radio Engineers, headquartered in New York City. The organisation is responsible for the creation of many international standards used in AV and many other fields.
IGMP Internet Group Management Protocol is a communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships. IGMP is an integral part of IP multicast.
IGMP Snooping The process of listening to Internet Group Management Protocol (IGMP) network traffic to control delivery of IP multicasts. Network switches with IGMP snooping listen in on the IGMP conversation between hosts and routers and maintain a map of which links need which IP multicast transmission. Multicasts may be filtered from the links which do not need them, conserving bandwidth on those links.
IGMP Snooping Querier An IGMP Snooping Querier manages the messaging and updating of information related to multicast groups within a VLAN.  Configuration of an IGMP querier is required to manage multicast traffic when no when no multicast router is present on the VLAN.
IP Address An Internet Protocol (IP) Address is used for network communication between computer devices. The IP address allows a device to be identified on the network
IR Infrared. In AV systems, IR is typically used for one-way control and automation of third-party controllable devices
LAN Local Area Network (LAN) is a network of interconnected computers within a building or department
Matrix Switcher Video routing AV equipment with the capability to route any input to any output, or route any input to multiple outputs
Multicast Network group communication messaging where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution
Rendevous Point (RP) A Rendevous Point is a router within a multicast-enabled network that receives and directs AV traffic and signalling messages between encoders and decoders. It can be configured within a router, or within some Layer 3-enabled switch models.
Picture-in-Picture (PIP); A combined video image composed of two or more video sources. Combined images may be side by side taking up half the viewable area, or one image may take up the entire viewable area with the other displayed on an inset window positioned in the corner
QoS;

Traffic Shaping

Quality of Service is a method of prioritising specific, time-sensitive network data traffic to ensure it reaches its destination with minimal delay
RS232;

RS422;

RS485

A telecommunications standard for serial communication and data transmission. In AV systems, typically used for point-to-point two-way control and automation of third-party controllable devices
TCP/IP A suite of communications protocols to connect computers on the internet and is the standard for transmitting data over networks.
UDP/IP The User Datagram Protocol (UDP) is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, sometimes known as datagrams, to other hosts on an Internet Protocol (IP) network without requiring other communications to set up special transmission channels or data paths.
Unicast A one-to-one transmission from one point in the network to another point; that is, one sender and one receiver.
VLAN / Subnet A Virtual Local Area Network (VLAN) is a logical partition of a physical LAN allowing multiple devices to be physically connected to the same or different network switches and still be part of the same network, communicating with each other using MAC addresses to send and receive Ethernet frames between devices. VLANs are a Layer-2 concept, operating at the Data-Link layer.

A Subnet also provides a logical partition of a physical/virtual LAN, using IP addresses to send and receive Packets with each other, operating at the Layer-3 Network layer. Packets may be sent to other devices on the same subnet, or to other subnets through a router or gateway.

Subnets and VLANs are often deployed on a 1:1 basis for simplicity, but it is entirely possible to have mutliple IP subnets within a single VLAN.

For further informattion on the TCP/IP model, see *INSERT REFERENCE*

Wi-Fi Wi-Fi is a family of radio technologies that is commonly used for the wireless local area networking (WLAN) of devices which is based around the IEEE 802.11 family of standards.
WLAN A wireless LAN (WLAN) is a wireless network that links two or more devices using wireless communication to form a local area network (LAN) within a defined area such as a home, school, computer laboratory, campus, office building etc.
Zero-configuration networking (zeroconf)  A set of technologies that automatically creates a usable network based on the Internet Protocol suite (TCP/IP) when computers or network peripherals are interconnected. It does not require manual operator intervention or special configuration servers.

 

Stakeholders

Below is a list of stakeholders commonly involved in the planning, deployment, and maintenance of an AV over IP solution:

    • AV and ICT Managers (design of integrated technology)
    • End Users (functionality, features, and user experience)
    • Facilities Management (passive network, cabling, cable paths & patching infrastructure) 

 

Key Relationships for a Successful Implementation

Video encoding and decoding technology, as well as the underlying ICT enterprise network, are vital elements of successfully delivering an AV over IP solution. Equally crucial to selecting the correct hardware for the job is ensuring that key relationships are fostered between audiovisual and institutional network design & operational teams. Bringing these key stakeholders in with clear functional and technical requirements of an AV over IP solution, supported by vendor-specific whitepapers can go a long way in fostering healthy, respectful and successful relationships and deployments that are a joint effort between colleagues and teams.

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