IP Video

Today there is a tremendous amount of interest in video and recent rapid developments in the performance of processing, storage capacity and in bandwidth availability, have allowed video services to be extended to IP networking.

As it becomes easier to compress and transport video, many businesses and service providers have increasingly adopted IP Video allowing high quality video to be transmitted for interactive communications and broadcasts.

Example Applications
PC to PC internet video calling is a service that has been available for some time using PC based video calling clients, webcams, and telephony headsets. The advent of cost effective broadband access mechanisms such as cable and DSL have increased the popularity of web video calling. The advent of end to end Quality of Service (QoS) guarantees from ISPs could enable this service to mature commercially.

3rd Generation mobile operators around the world have launched handset to handset video calling capabilities and they plan to soon extend calling to PCs on IP networks such as the internet. Some of these implementations use circuit switched network (using ITU H.324M recommendation) and some use basic quality of service (QoS) techniques on 3G packet networks. However the evolution of this type of service is using SIP based call control over 3G packet networks running multiple services with high QoS capabilities.

Video Conferencing has been around for many years in the traditional circuit switched world using n x 64kbit/s ISDN. However the difficulty in conference set up, the frequent problems in maintaining connections and its prohibitive costs have lead to a surge in the take up of IP video conferencing solutions. IP implementations offer a much simpler conference set up and flexibility in participant location allowing desktop users to join in with room based conferences.

Broadcast TV industry has adopted IP for high quality TV and Video on Demand pay-per-view over cable, DSL and satellite infrastructures as part of interactive TV and their overall strategy to integrate broadcast TV with Internet technologies.

Security & Surveillance applications allow video from CCTV security cameras and other real time surveillance such as road traffic monitoring to be sent to monitors and handheld devices over LAN, WAN or wireless infrastructures. Benefits include the ability to multicast the video to multiple locations and the ability to control & manage the cameras remotely.

Other examples of video over IP applications include: distance learning for schools and businesses to deliver courseware, lectures or interactive training; live broadcast sport matches, music concerts, news or Parliament over the internet; telemedicine training for medical students.

Video Compression
Digital video data rates are very large, typically in the range of 150Mbits/sec and consume a lot of the bandwidth, storage and computing resources. For this reason, Video Compression standards have been developed to eliminate picture redundancy, allowing video information to be transmitted and stored in a compact and efficient manner.

Discrete Cosine Transform (DCT) based compression algorithms and international standards were developed and today the two most widely used and accepted are ITU-T H.26x (Video codec for audiovisual services), and MPEG (Motion Picture Experts Group).

H.261 is the oldest compression algorithm, similar to JPEG still image compression, developed for transmission of video at a rate of multiples of 64Kbps (e.g. ISDN) videoconferencing systems. H.263 is optimised for low bit rate coding applications of 64kbit/s or less (e.g. PSTN & H.323 video conferencing).

MPEG algorithms were developed to address the need for higher quality pictures and increased system flexibility required by multi-media systems and leverages the efforts behind JPEG and H.261 algorithms. MPEG-1 offers high compression and moderate quality for Video CD and CD-ROM. MPEG-2 published in 1999 (ISO 13818-2) offers high compression and high quality for DVD-Video, SVCD, HDTV, Interactive Storage Media, CATV (e.g. up to 100Mb/s), broadcast TV & other applications using interlaced images. MPEG-4 published 2000 (ISO/IEC 14496) is more efficient at low bandwidths by reducing frame rates to 15 or less frames per second and offers a rich set of tools to improve compression performance, error robustness and flexibility for applications such as Streaming Media and 3G mobile video communications.

Performance
Video requires careful engineering of the underlying IP infrastructure whether it be native IP, IP over ATM or IP over DSL. Packet loss, transmission delay, delay variation (jitter) can all generate distortion of the video introducing the need for QoS techniques.

The type of QoS techniques adopted to police and prioritise video traffic will depend upon the underlying network, the amount of compression used, the available bandwidth and whether video is integrated with other traffic types (such as voice and data services) on a common infrastructure.

MPEG coding schemes have numerous higher-layer mechanisms to protect and recover video streams. These include error correction, packet priority protection, structured packing, leaky prediction encoding, insertion, cyclic refresh, lapped orthogonal transform, and concealment.

The Importance of Video
Over the past few years there has been an increased volume of audio-visual data available in our everyday lives and this increased exposure is fuelling the demand and expectation for video services. Technology advances in compression techniques and the availability of broadband infrastructure are increasing the reach and variety of IP Video applications.

For many people the ability to see clearly the face of the person that they are talking to is an important factor in building trust and confidence. For many service providers the advantages of using IP as a multipurpose transport network for carrying video along with other media types are becoming clearer.