6Video technology

Video devices include cameras and camera systems, consumer electronics, video recorders, streaming, and systems for recording and sharing content. They addressed in the following chapter.

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Schematic of the CCTV system in a TV studio

Cameras and camera systems form one large area of ​​video technology. The basic division includes three main categories:

  1. installation cameras
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Examples of installation cameras
  1. portable cameras
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Examples of portable cameras
  1. special cameras
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Examples of special cameras

In addition, cameras and camera systems can be divided by Interface to Digital (HDMI (High-Definition Multimedia Interface), DVI (Digital Visual Interface), SDI (Serial Digital Interface)), IP (Internet Protocol) for Ethernet Streaming, USB and combined (may have different interface combinations from the mentioned above).

Consumer video products include DVB (Digital Video Broadcast) receivers, TVs and DVD/Blu-ray players and recorders. These products are used in AV/IT installations as complementary to the system, not as the main solution. Consumer electronics is characterized by a low service life (i.e. no 24/7 operation), limited functionality for integration with other AV components, limited support by the manufacturer or distributor, often changing assortment.

Video recorders are video recording equipment for conventional recording, they can be divided into single channel and multichannel recorders, or similarly to cameras, according to the type of available interfaces.

Nowadays, a very interesting and popular application area is Streaming.

Streaming is a continuous audiovisual technology for transfer between the source and the end user. At present, streaming is mainly used for transmission of audiovisual material over the Internet (Webcasting). Webcasting can take place in real-time (Internet TV or radio) or as VoD (Video on Demand) – e.g. YouTube. To stream video to multiple users at the same time, the operator must have a stream server (in addition to the content) that communicates with target computers and streaming data.

For the transmission of audiovisual material over the Internet, codecs are used to reduce the volume of transmitted data. Flash codecs, MPEG-4 (Moving Picture Experts Group-4), Windows Media, Real Time and QuickTime are the mostly used codecs. Even so, transmission of the TV resolution video (720×576) is very demanding. Therefore, streaming at 320x240 pixels at 256 to 512 kbps was the most popular. Nowadays, we can quite commonly encounter extremes such as 4K streaming, offered for example by YouTube or Netflix.

Streaming audio primarily uses WMA (Windows Media Audio), MP3, OGG, and AAC+ (Advanced Audio Coding+) codecs in data streams, typically from 16 to 256 kbps. Audio can be streamed as singlebitrate, i.e. either a constant bitrate or multibitrate, which is a number of constant data streams transmitted together in one data stream between the encoder and the server. A player that can play multibitrate stream from the server can then automatically change the sound quality if the Internet connection deteriorates/improves.

The distribution of AV stream to the viewer is basically possible with three basic methods:

Apart from the above-mentioned video and audio distribution to the Internet, Streaming is also used in AV systems. In this case, bitrate is not a critical issue - it can use the full bandwidth offered within the local LAN, which can be up to 1 Gbps. However, one of the codecs must be used here as well, which compresses the signal and reduces the data stream. The uncompressed 1080p signal can easily reach up to 10 Gbps.

The most common codecs are in H.264 and JPEG2000. However, manufacturers produce a number of custom codecs, which are, however, mostly compatible with only one brand of products. Codecs can either be in the form of hardware or they are installed as software on a dedicated computer. In addition to image and sound, the selected codecs can also transmit other data, such as data for keyboard, mouse, USB peripherals, IR (InfraRed) and RS232 (Recommended Standard 232) signals, etc. It is therefore possible to transmit complex data over a single UTP cable within a computer network for data processing in the AV system. Some peripherals can also be powered on the same cable (PoE technology).

In association with AV content streaming, it is also worth mentioning the concept of CDN (Content Delivery Network). It is a network that provides broadcasting of an AV content by broadcasting to public or private networks. In essence, this is similar to DVB-T (Digital Video Broadcast - Terrestrial) or DVB-S (DVB-Sattelite), but takes place in an IP network environment. Providers are paid. Availability, capacity and archives are guaranteed for a fee. Custom CDNs are often run by large organizations.

Their traffic is expensive (for example, Mediasite EVP Server (Event Visualization Platform Server)).