Technologies of data transmission in video conferencing systems
The methods and technologies, associated with video and audio data transmission in video conferencing systems were discovered. Existing problems in the field of data transmission in conferencing systems via the Internet and methods for their solution were considered. The most widely used technologie...
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Інститут проблем математичних машин і систем НАН України
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| Cite this: | Technologies of data transmission in video conferencing systems / V.V. Kazymyr, M.V. Tevkun, O.P. Drozd // Математичні машини і системи. — 2013. — № 4. — С. 64-69. — Бібліогр.: 10 назв. — англ. |
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| author | Kazymyr, V.V. Tevkun, M.V. Drozd, O.P. |
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| citation_txt | Technologies of data transmission in video conferencing systems / V.V. Kazymyr, M.V. Tevkun, O.P. Drozd // Математичні машини і системи. — 2013. — № 4. — С. 64-69. — Бібліогр.: 10 назв. — англ. |
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| description | The methods and technologies, associated with video and audio data transmission in video conferencing systems were discovered. Existing problems in the field of data transmission in conferencing systems via the Internet and methods for their solution were considered. The most widely used technologies of data transmission in the video conferencing systems via the Internet were analyzed. The concept of telepresence and features of video conferencing systems that it provides were considered. Conclusions about the appropriateness of using different technologies of video and audio data transfer depending on the type of video conferencing system were made.
Досліджено методи і технології передачі відео- та аудіоданих у системах відеоконференцзв’язку. Розглянуто існуючі проблеми у сфері передачі даних у системах конференцзв'язку через Інтернет і методи їх вирішення. Проаналізовано найбільш поширені технології передачі відео- та аудіоданих у системах відеоконференцзв'язку через Інтернет. Розглянуті поняття телеприсутності і особливості систем відеоконференцзв'язку, що її забезпечують. Зроблено висновки про доцільність використання різних технологій передачі відео- та аудіоданих залежно від типу системи відеоконференцзв'язку.
Исследованы методы и технологии передачи видео- и аудиоданных в системах видеоконференцсвязи. Рассмотрены существующие проблемы в сфере передачи данных в системах конференцсвязи через Интернет и методы их решения. Проанализированы наиболее распространенные технологии передачи видео- и аудиоданных в системах видеоконференцсвязи через Интернет. Рассмотрены понятие телеприсутствия и особенности систем видеоконференцсвязи, которые его обеспечивают. Сделаны выводы о целесообразности использования различных технологий передачи видео- и аудиоданных в зависимости от типа системы видеоконференцсвязи.
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64 © Kazymyr V.V., Tevkun M.V., Drozd O.P., 2013
ISSN 1028-9763. Математичні машини і системи, 2013, № 4
UDC 004.773.5
V.V. KAZYMYR*, M.V. TEVKUN**, O.P. DROZD**
TECHNOLOGIES OF DATA TRANSMISSION IN VIDEO CONFERENCING SYSTEMS
*Chernihiv State Institute of Economics and Management, Chernihiv, Ukraine
**Chernihiv National Technological University, Chernihiv, Ukraine
Анотація. Досліджено методи і технології передачі відео- та аудіоданих у системах відеоконфе-
ренцзв’язку. Розглянуто існуючі проблеми у сфері передачі даних у системах конференцзв'язку че-
рез Інтернет і методи їх вирішення. Проаналізовано найбільш поширені технології передачі відео-
та аудіоданих у системах відеоконференцзв'язку через Інтернет. Розглянуті поняття телепрису-
тності і особливості систем відеоконференцзв'язку, що її забезпечують. Зроблено висновки про
доцільність використання різних технологій передачі відео- та аудіоданих залежно від типу сис-
теми відеоконференцзв'язку.
Ключові слова: відеоконференцзвязок, телеприсутність, вебінар, базовий протокол «floor control»,
H.323, Flash-технології, RTMP.
Аннотация. Исследованы методы и технологии передачи видео- и аудиоданных в системах видео-
конференцсвязи. Рассмотрены существующие проблемы в сфере передачи данных в системах
конференцсвязи через Интернет и методы их решения. Проанализированы наиболее распростра-
ненные технологии передачи видео- и аудиоданных в системах видеоконференцсвязи через Интер-
нет. Рассмотрены понятие телеприсутствия и особенности систем видеоконференцсвязи, кото-
рые его обеспечивают. Сделаны выводы о целесообразности использования различных технологий
передачи видео- и аудиоданных в зависимости от типа системы видеоконференцсвязи.
Ключевые слова: видеоконференцсвязь, телеприсутствие, вебинар, базовый протокол «floor con-
trol», H.323, Flash-технологии, RTMP.
Abstract. The methods and technologies, associated with video and audio data transmission in video con-
ferencing systems were discovered. Existing problems in the field of data transmission in conferencing
systems via the Internet and methods for their solution were considered. The most widely used technolo-
gies of data transmission in the video conferencing systems via the Internet were analyzed. The concept of
telepresence and features of video conferencing systems that it provides were considered. Conclusions
about the appropriateness of using different technologies of video and audio data transfer depending on
the type of video conferencing system were made.
Keywords: videoconferencing, telepresence, webinar, Binary Floor Control Protocol, H.323, Flash-
technologies, RTMP.
1. Introduction
Conferencing is a technology that performs the ability of synchronous (simultaneous) communi-
cation between several interlocutors. Current technology has great popularity in the modern
world due to providing wide range of possibilities. Conferencing connects users, placed at great
distances from each other (in different parts of the world). Provided communication is not limited
by few users: conferencing allows performing simultaneous connection between huge numbers of
participants. Conferencing is a duplex technology that is means that all conference participants
have the ability to talk and hear each other. Considering all presented features the conclusion can
be made that the technology of conferencing is required for meetings, workshops and different
kinds of conferences. The distance education is also based on the current technology.
In the nearest past the only device, which allows performing conferencing, was telephone.
Usage of telephone allows conducting of audio conferences: the participants can hear each other,
can talk and express opinions, consult with each other and discuss new ideas, but the visual
contact is not available. They can’t see interlocutor, send each other different kinds of tables and
ISSN 1028-9763. Математичні машини і системи, 2013, № 4 65
images that are necessary to perform complete work and obtain quality results. So the next stage
of the development of conferencing is the video conferences, which were designed in 1970th.
Video conferencing is a communication technology, which provides interaction of two or
more subscribers and the exchange of audio and video data between them in real time mode.
Video conferencing is applicable in many areas, such as business, distance education and
medicine and performed using video conferencing systems [1]. Personal video conferencing
systems provide the opportunity to communicate "face to face" or "one to one" between two users
in real time mode. Group video conferencing systems enable videoconferences, where huge
numbers of interlocutors, situated all over the world, can take part.
There are several methods of arrangement of communication between interlocutors. The
most available and the cheapest method is Internet. However the technologies of conferencing via
Internet are not standardized that has negative impact on the interoperability, depending of
platform and security issues. The investigation of the different technologies of data transfer in
conferencing via Internet is presented in the paper.
1.1. Related work
The communication channel between users is the basic element of videoconference. There are
several methods of arrangement of communication channels, such as ISDN, technology IP VPN
MPLS and Internet. ISDN (Integrated Services Digital Network) is not widely used due its’
significant disadvantages, such as low recovery efficiency of communication channels,
difficulties in breakdown control and high price. IP VPN MPLS technology is the most secured
method due to usage of additional protection technologies, such as VPN (Virtual Private
Network) and MPLS (Multiprotocol Label Switching). VPN allows creation of one or more
secure network connections (logical network) over another network. MPLS is data transfer
mechanism which emulates various properties of circuit switched networks over packet switched
networks. IP VPN MPLS is used in case of high priority of data protection. However the most
available and the cheapest method for organization of communication channel is Internet. On the
other hand usage of Internet has some disadvantages [2]. The quality of communication session
can be low, because the Internet is not guaranteed channel for audio and video data transmission.
The problem of data protection is also critical in case of using Internet as the communication
channel. The technologies, which provide data transfer in video conferencing system via Internet,
must consider these possible problems. Other problems, associated with technologies of video
conferencing via Internet, appear due to the lack of standardization. The task of ensuring the
interaction between video conferencing systems, developed using different data transfer
technologies, is important for emerging communication technologies.
1.2. Purpose
The aim of the current paper is to consider the most widely used technologies of video and audio
data transmission in the video conferencing systems via the Internet, to investigate their features,
advantages and disadvantages and to analyze the appropriateness of using different technologies
of video and audio data transfer depending on the type of video conferencing system (webinar,
teleconference etc).
2. Investigations
To solve the problems, connected with video and audio data transmission via Internet, the addi-
tional technologies of data transfer should be applied. One of the possible ways of solution is
usage of video conferencing protocols [3]. Video conferencing protocol is a set of arrangements
that defines data communication between different software. The protocols determine the way of
the data transfer and processing of network errors, and also enable the development of standards
66 ISSN 1028-9763. Математичні машини і системи, 2013, № 4
that are not linked to a particular hardware platform. To perform audio and video conferencing
over telecommunications networks ITU-T (International Telecommunication Union - Telecom-
munication sector) has developed a series of recommendations H.32x (H.320, H.321, H.322,
H.323, H.324) [4].
2.1. Recommendation H.323
H.323 is a recommendation, developed by ITU-T (International Telecommunication Union - Tel-
ecommunication sector) that determines the set of standards for multimedia data transfer in
packet switched networks [4]. Recommendations of ITU-T, included in H.323 standard, define
the order of functioning of user's terminals in networks with the divided resources and not guar-
anteed quality of service (QoS). Standard H.323 is not connected with IP protocol, however, the
most of implementations is based on it. The set of recommendations determines network compo-
nents, protocols and procedures that allow organizing of multimedia communication in packet
switched networks.
H.323 standard identifies different H.323 entities as the functional units of a complete
H.323 network that allow conduction of bilateral (point-to-point) and multilateral (point-
multipoint) multimedia conferences. There components are terminal, gateway, gatekeeper and
MCU (Multipoint Control Unit) [5].
Terminal is a PC or other self-contained unit that is capable to perform multimedia appli-
cation. Terminal must provide sound communication and can additionally support video and data
transmission. H.323 terminal should support such protocols: H.245 for negotiation of connection
parameters, Q.931 for establishment and control of connection, RAS for interaction with gate-
keeper, RTP/RTCP for optimization of delivery of audio/video flow and H.450 set of protocols
for support necessary for H.323 additional types of services.
Gateway is not necessary component of H.323 network. It is required only in case when
the connection with the terminal of different standard should be established. Such communication
is provided using the translation of protocol of connection installation and rupture and data
transmission formants.
Gatekeeper is a centre of calls processing in area of its determinate zone and performs ba-
sic functions of calls management. Zone is defined as the set of all terminals, gateways and MCU
that are controlled by one gatekeeper. Gatekeeper is not necessary component of H.323 network,
but if it’s present in the network, terminals and gateways should use it services. The basic servic-
es of gatekeeper are address translation (mapping), access control, bandwidth management, man-
agement of connection establishment process, authorization, calls control etc.
Multipoint Control Unit provides connection of three or more H.323 terminals. All ter-
minals, participated in conference, establish connection with MCU. MCU server maintains confe-
rence recourses, determines possibilities of terminals in audio and video data processing, and de-
termines audio and video data streams.
Recommendation H.323 provides bandwidth management, interoperability, platform
independence, support of multipoint conferences, multicast transmission and addressing, codec’s
standardization.
Recommendation H.323 contains [5]:
– standards H.264, H.263, H.261, which define methods of video data encoding and
decoding;
– standards G.722, G.711, G.728 et al., which determine methods of audio data encoding
and decoding;
– standard H.225, which defines methods of audio, video, data and control streams
multiplexing and demultiplexing and management of call, access, registration of participants and
identification of the current state;
ISSN 1028-9763. Математичні машини і системи, 2013, № 4 67
Fig. 1. Complete H.323 protocol stack
– standard H.245, which determines alarm, management and control, including multipoint
conferences;
– standards of T series (T.120
et al.), which determine the
interaction of software and hardware
during the data exchange.
Complete H.323 protocol
stack is shown in figure 1.
The emergence of standard
H.323, which describes the
mechanisms of interaction between
devices providing the transmission of
voice and video over IP networks,
allows combining devices from
different manufacturers in one
network that is effective for specific
communication network. Video conferencing systems, based ob the H.323, perform high quality
of service (QoS) and provide wide range of features and opportunities, including TelePresenсe
[6]. TelePresence is videoconferencing technology, which provides the maximum possible effect
of the presence of the interlocutors in the same room (or study hall.) It allows user get an
impression that he is located and acts in a position different from his physical location. However,
technology of TelePresence is not popular due high cost of required equipment. Despite the high
quality of communication and obtained data, video conferencing systems, developed using
H.323, are not widely used for the same reason, especially in case of multipoint conference.
MCU and other entities of H.323 conference often are not available for small companies, so they
prefer usage of other systems that do not require additional costs for software and hardware, and
are available through Internet browser. Current type of video conferencing systems is called
webinar [7]. Systems of webinars show lower quality of communication and do not guarantee the
security of transmitted information, but are widely distributed due it high availability and large
number of OpenSource applications. Webinars systems are not based on H.323 and often
developed using Flash technology and RTMP protocol.
2.2. Flash-technologies and Real Time Messaging Protocol (RTMP)
Flash is a multimedia platform, developed by Adobe to design web-applications and multimedia
presentations. Nowadays it is widely used for design of animation and games and to reproduction
of video and audio data on the web-pages.
Adobe Flash enables work with vector, raster and three-dimensional graphics using the
GPU, and supports bidirectional streaming of audio and video broadcast. The special software,
named Flash Player, is required to perform Flash-content. Basically, Flash Player is a virtual
machine, which performs code of flash-application, downloaded from the Internet. Vector
morphing that is gradual "overflow" of one keyframe to another, is a foundation of Flash
animation. The performance of Flash in browsers is better than the performance of Javascript
machine, but it worse than the performance of the applications working without virtual machines.
The standard extension for compiled flash-files (animation, games and interactive
applications) is. SWF (Shockwave Flash). Videos in Flash format are presented as files with the
extension FLV or F4V. In this case Flash is used only as a container for video. FLA extension
matches the format of the working files in the development environment.
The main disadvantage of flash-applications is the excessive load on the processor
associated with the ineffectiveness of the Flash Player virtual machine. The second major
drawback of flash-applications is the lack of errors control, which leads to frequent failures of the
68 ISSN 1028-9763. Математичні машини і системи, 2013, № 4
Fig. 2. Binary Floor Control Protocol
applications, and, in some cases, of the browser. However Flash-technology is used in popular
OpenSource webinar systems, such as OpenMeetings and BigBlueButton.
The Real-Time Messaging Protocol (RTMP) was developed for high-performance trans-
mission of audio, video, and data between Adobe Flash Platform technologies [8]. Adobe’s Real
Time Messaging Protocol (RTMP) provides a bidirectional message multiplex service over a reli-
able stream transport, such as TCP, intended to transfer parallel streams of video, audio, and data
messages, with associated timing information, between a pair of communicating peers. (RFC
RTMP) Different classes of messages received different priorities, which impact on their order in
transport stream when transportation options are limited.
The RTMP is Adobe technology and RTMP server has high cost. However the Red5
OpenSource server was designed using Java and widely used in modern web-applications to
perform RTMP. Red5 server provides audio and video data streams (FLV and MP3), recording of
client data streams (FLV only), shared objects, live stream publishing.
The most widely used OpenSource webinar systems OpenMeetings and BigBlueButton
are developed using Flash-technology and Red5 server.
2.3. The Binary Floor Control Protocol (BFCP)
To solve existing problems of video conferencing via Internet IETF created working group,
named “Centralized Conferencing” (XCON). The target of XCON is to establish standards of
video conferencing including development of such technologies as basic «floor control» protocol
Binary Floor Control Protocol (BFCP), the mechanism of the membership and authorization, the
mechanism of management of combination of different types of media files (audio, video, text)
and its description, the mechanism of notification about the related to the conference events /
changes (e.g. changing of protocol).
Floor control is a management of joint or exclusive access to shared resources in a
(multiparty) conferencing environment [9]. Floor control also completes functions, realized by
other protocols, such as conference and media session setup, conference policy manipulation and
media control. During a conference, the applications require to control access to shared recourses
(e.g. right to send media to a particular session). Floor control provides the ability for such
applications to coordinate shared or exclusive access to the resources.
A floor control protocol is used to perform transmission of the floor control messages
between the floor chairs (moderators), the floor control server and the participants of the
conference. A centralized architecture with one key point, transmitted all messages (the floor
control server), is used. Processing of the floor control requests is performed by floor chairs or by
server (depending of
the policy) [10]. The
performance of Bi-
nary Floor Control
Protocol (BFCP) is
shown in figure 2.
Floor partici-
pants send floor
requests to floor
control servers. Floor
chairs send floor
control server decisions about floor requests. Floor control servers permit (or deny) requests to
access a required resource from floor participants and inform floor participants and floor chairs
about the status of request.
ISSN 1028-9763. Математичні машини і системи, 2013, № 4 69
3. Conclusions
Due to the existing problems, associated with transmission of video and audio data via the Inter-
net, such as data protection and unstable communication channel, the additional technologies for
multimedia data transferring should be used to provide the work of video conferencing systems.
Several technologies are used to perform data transfer via Internet in video conferencing systems;
the most frequently used are H.323, Flash and RTMP. H.323 standard (communication protocol)
provides the highest quality of service, including the quality of video signal, security of trans-
ferred data and implementation of TelePresence. However current technology is used mostly in
closed expensive systems and required high cost software and hardware that make it not available
for widespread use. Another existing type of video conferencing systems is called webinars,
performs using web-browser and has OpenSource editions. OpenSource webinars systems, such
as OpenMeetings and BigBlueButton, are mostly implemented using Flash and RTMP (Red5) to
perform video and audio data transmission. Webinars systems have low quality of service and
don’t provide data protection, but are preferred due to low cost and high availability.
REFERENCES
1. Sinepol V.S. Systems of videoconferencing. Series “Communications and business”/ V.S. Sinepol,
I.A. Cikin. – M.: OOO “Mobile Communications”, 1999. – Р. 7 – 11.
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len. – Режим доступу: http://www.oreillynet.com.
3. Schulzrinne H. The IETF Internet Telephony Architecture and Protocols / H. Schulzrinne, J. Rosenberg
// IEEE Network. – 1999. – May/June. – Р. 18 – 23.
4. ITU “H.323: Packet Based Multimedia Communications Systems” [Електронний ресурс]. – 1998. –
Feb. – 125 p. – Режим доступу: http://www.itu.int.
5. Toga J. ITU-T Standardization activities for interactive multimedia communications on packet-based
networks: H.323 and related recommendations / J. Toga, J. Ott // IEEE Computer Networks. – 1999. –
Feb. – P. 205 – 223.
6. Minsky M. TelePresense / M. Minsky // OMNI. – 1980. – June. – Р. 45 – 52.
7. Webinar Definition [Електронний ресурс // PC Magazine Encyclopedia. – 2008. – Режим доступу:
http://www.pcmag.com.
8. Adobe’s Real Time Messaging Protocol Specification [Електронний ресурс]. – Режим доступу:
http://www.adobe.com.
9. The Binary Floor Control Protocol (BFCP) (RFC 4582) [Електронний ресурс]. – Режим доступу:
http://tools.ietf.org.
10. Requirements for Floor Control Protocols (RFC 4376) [Електронний ресурс]. – Режим доступу:
http://tools.ietf.org.
Стаття надійшла до редакції 10.10.2013
|
| id | nasplib_isofts_kiev_ua-123456789-84272 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1028-9763 |
| language | English |
| last_indexed | 2025-12-07T18:56:45Z |
| publishDate | 2013 |
| publisher | Інститут проблем математичних машин і систем НАН України |
| record_format | dspace |
| spelling | Kazymyr, V.V. Tevkun, M.V. Drozd, O.P. 2015-07-05T07:29:15Z 2015-07-05T07:29:15Z 2013 Technologies of data transmission in video conferencing systems / V.V. Kazymyr, M.V. Tevkun, O.P. Drozd // Математичні машини і системи. — 2013. — № 4. — С. 64-69. — Бібліогр.: 10 назв. — англ. 1028-9763 https://nasplib.isofts.kiev.ua/handle/123456789/84272 004.773.5 The methods and technologies, associated with video and audio data transmission in video conferencing systems were discovered. Existing problems in the field of data transmission in conferencing systems via the Internet and methods for their solution were considered. The most widely used technologies of data transmission in the video conferencing systems via the Internet were analyzed. The concept of telepresence and features of video conferencing systems that it provides were considered. Conclusions about the appropriateness of using different technologies of video and audio data transfer depending on the type of video conferencing system were made. Досліджено методи і технології передачі відео- та аудіоданих у системах відеоконференцзв’язку. Розглянуто існуючі проблеми у сфері передачі даних у системах конференцзв'язку через Інтернет і методи їх вирішення. Проаналізовано найбільш поширені технології передачі відео- та аудіоданих у системах відеоконференцзв'язку через Інтернет. Розглянуті поняття телеприсутності і особливості систем відеоконференцзв'язку, що її забезпечують. Зроблено висновки про доцільність використання різних технологій передачі відео- та аудіоданих залежно від типу системи відеоконференцзв'язку. Исследованы методы и технологии передачи видео- и аудиоданных в системах видеоконференцсвязи. Рассмотрены существующие проблемы в сфере передачи данных в системах конференцсвязи через Интернет и методы их решения. Проанализированы наиболее распространенные технологии передачи видео- и аудиоданных в системах видеоконференцсвязи через Интернет. Рассмотрены понятие телеприсутствия и особенности систем видеоконференцсвязи, которые его обеспечивают. Сделаны выводы о целесообразности использования различных технологий передачи видео- и аудиоданных в зависимости от типа системы видеоконференцсвязи. en Інститут проблем математичних машин і систем НАН України Математичні машини і системи Інформаційні і телекомунікаційні технології Technologies of data transmission in video conferencing systems Технології передачі даних у системах відеоконференцзв’язку Технологии передачи данных в системах видеоконференцсвязи Article published earlier |
| spellingShingle | Technologies of data transmission in video conferencing systems Kazymyr, V.V. Tevkun, M.V. Drozd, O.P. Інформаційні і телекомунікаційні технології |
| title | Technologies of data transmission in video conferencing systems |
| title_alt | Технології передачі даних у системах відеоконференцзв’язку Технологии передачи данных в системах видеоконференцсвязи |
| title_full | Technologies of data transmission in video conferencing systems |
| title_fullStr | Technologies of data transmission in video conferencing systems |
| title_full_unstemmed | Technologies of data transmission in video conferencing systems |
| title_short | Technologies of data transmission in video conferencing systems |
| title_sort | technologies of data transmission in video conferencing systems |
| topic | Інформаційні і телекомунікаційні технології |
| topic_facet | Інформаційні і телекомунікаційні технології |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/84272 |
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