Lesson Twenty-Six

ONLINE-VIDEO – VIDEO ON-DEMAND – MOBILE VIDEO

Technology.

H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding) is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video. The final drafting work on the first version of the standard was completed in May 2003.

H.264/MPEG-4 AVC is a block-oriented motion-compensation-based codec standard developed by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC JTC1 Moving Picture Experts Group (MPEG). The project partnership effort is known as the Joint Video Team (JVT). The ITU-T H.264 standard and the ISO/IEC MPEG-4 AVC standard (formally, ISO/IEC 14496-10 – MPEG-4 Part 10, Advanced Video Coding) are jointly maintained so that they have identical technical content.

Answer the questions:

1. When was the first version of the standard for video compression completed?

2. What does VCEG stand for?

3. What does MPEG stand for?

Video on demand (VOD)

or audio and video on demand (AVOD) are systems which allow users to select and watch/listen to video or audio content on demand. IPTV technology is often used to bring video on demand to televisions and personal computers Catch up TV is a form of video on demand.

Television VOD systems either stream content through a set-top box, a computer or other device, allowing viewing in real time, or download it to a device such as a computer, digital video recorder, also called a personal video recorder or portable media player for viewing at any time. The majority of cable- and telco-based television providers offer both VOD streaming, including pay-per-view and free content, whereby a user buys or selects a movie or television program and it begins to play on the television set almost instantaneously, or downloading to a DVR rented from the provider, or downloaded onto a PC, for viewing in the future. Internet television, using theInternet, is an increasingly popular form of video on demand.

Some airlines offer AVOD as in-flight entertainment to passengers through individually controlled video screens embedded in seatbacks or armrests or offered via portable media players. Airline AVOD systems offer passengers the opportunity to select specific stored video or audio content and play it on demand including pause, fast forward, and rewind.

Download and streaming video on demand systems provide the user with a large subset of VCR functionality including pause, fast forward, fast rewind, slow forward, slow rewind, jump to previous/future frame etc. These functions are called 'trick modes'. For disk-based streaming systems which store and stream programs from hard disk drive, trick modes require additional processing and storage on the part of the server, because separate files for fast forward and rewind must be stored. Memory-based VOD streaming systems have the advantage of being able to perform trick modes directly from RAM, which requires no additional storage on the part of the processor.

It is possible to put video servers on LANs, in which case they can provide very rapid response to users. Streaming video servers can also serve a wider community via a WAN. Download VOD services are practical to homes equipped with cable modems or DSL connections. Servers for traditional cable and telco VOD services are usually placed at the cable head-end serving a particular market as well as cable hubs in larger markets. In the telco world, they are placed in either the central office, or a newly created location called a Video Head-End Office (VHO)

Push video on demand is a technique used by a number of broadcasters on systems that lack connectivity to provide true video on demand or by broadcasters who want to optimize their video streaming infrastructure by pre-loading the most popular contents to the consumer device. A push VOD system uses a personal video recorder (PVR) to store a selection of content, often transmitted in spare capacity overnight or all day long at low bandwidth. Users can watch the downloaded content at the time they desire, immediately and without any buffering issue. As content occupies space on the PVR hard drive, downloaded content is usually deleted after a week to make way for newer programs. The limited space on a PVR hard drive means that the selection of programs is usually restricted to most popular content. A new generation of Push VOD solution recently appeared on the market which, by using efficient error correction mechanisms, can free significant amount of bandwidth and that can deliver more than video e.g. magazines, interactive applications.

Near video on demand (NVOD) is a pay-per-view consumer video technique used by multi-channel broadcasters using high-bandwidth distribution mechanisms such as satellite and cable television. Multiple copies of a program are broadcast at short time intervals (typically 10–20 minutes) providing convenience for viewers, who can watch the program without needing to tune in at a scheduled point in time. This form is bandwidth intensive and is generally provided only by large operators with a great deal of redundant capacity and has been reduced in popularity as video on demand is implemented.

Answer the questions:

1. What can VOD and AVOD do?

2. 'What do ‘trick modes' include?

3. In which case do video servers provide a very rapid response to users?

4. What is NVOD?

Дата добавления: 2015-11-14