A significant portion of information that is transmitted on the modern Internet consists of multimedia data – this accounted for a whopping 70% in 2015! These are not just photos and audiovisual files; the Internet is gradually replacing traditional television and telephony by providing the real-time transmission of vast amounts of data with minimal delays, thus enabling interactive communication. Even individuals who prefer conventional solutions like televisions or landline phones often – even unknowingly – rely on the Internet as the medium for delivering content for them. This described trend is undoubtedly gaining momentum; therefore, the knowledge and understanding of those issues that are related to networked multimedia systems are of great importance for computer scientists. The Laboratory of Networked Multimedia Systems is a place where students can acquire practical knowledge in the representation, generation, storage, and processing of streaming multimedia data as well as in the mechanisms for their efficient transmission in contemporary computer networks.
The Laboratory of Networked Multimedia Systems is located in Room 4.22 in Building D-17.
The equipment and software that are available in the laboratory allow for the analysis of all aspects of networked multimedia systems, from their creation through their transmission in computer networks to their ultimate presentation to the end recipient. These include the following:
- • image and sound representation as well as coding methods;
• description of multimedia sessions;
• multimedia data-transmission protocols;
• suitability of different transport protocols for multimedia data transmission;
• issues that are related to the adaptability of multimedia information stream sizes;
• signaling protocols used in organizing multimedia sessions (RTSP, SIP, H.323);
• VoIP technology and standards used in this technology;
• group communication and multicast routing in IP networks;
• quality of service assurance in IP networks (DiffServ and IntServ architectures).
The laboratory includes the following equipment:
- • Real-time image- and sound-encoding devices: real-time MPEG-1, MPEG-2, MJPEG, and H.264 encoders that serve as sources of multimedia streams. These allow participants to compare the operations and parameters of different coding standards.
- • Analog and digital cameras that are connected to encoding devices, which allow users to influence the encoding process of moving images.
- • Streaming software servers that provide multimedia content, which enable the repetition of experiments with identical data.
- • A DVB tuner with DVB-T and DVB-S heads, which allow for the reception of digital television signals and their distribution over the computer network. Therefore, participants can temporarily become Internet television providers.
- • A professional video conferencing terminal. Users can familiarize themselves with the solution that is used by the CEOs of large companies during business meetings.
- • Modern personal computers with standard audiovisual equipment and specialized network and multimedia software.
- • IP phones and analog phones.
- • Semi-professional telephone exchange. Participants can build and configure simple telephone networks, thus defining their own numbering plans.
- • An amplifier and professional sound system.
- • A set-top-box device for receiving, storing, and presenting multimedia content on end-user devices.
- • Televisions and computer projectors that display high-definition images, which are essential for assessing their quality and the impact of the transmission parameters.
- • Numerous network devices that are used for building networks that transmit multimedia data and configuring QoS- and multicast-routing mechanisms. Transmissions can be conducted in IP networks based on Ethernet standards and wide-area network technologies as well as in ATM networks, thus guaranteeing the specified transmission quality.
Participants also have the opportunity to familiarize themselves with the professional multimedia infrastructure of AGH University of Science and Technology’s Center for Computer Science, which includes professional video-conferencing terminals, a conference bridge, an audiovisual stream transcoder, and a VoIP telephony infrastructure.
| Equipment Details
- • DICAS 2030 HD – H.264 HD encoder [http://www.gpl-uk.co.uk/files/dicas_2030_datasheet.pdf] (used for real-time H.264 HD stream-encoding demonstrations and stream management);
- • Cisco D9036 – H.264 HD encoder [http://www.cisco.com/en/US/prod/collateral/video/ps9159/ps9168/ps9178/7018589C.pdf];
- • NPoint – MPEG-1 encoder (used for hardware MPEG-1 compression demonstrations);
- • Optibase – hardware H.264 compression-expansion cards;
- • AVA – hardware MJPEG encoder (working on ATM network) [http://cmpe.emu.edu.tr/Courses/CMSE403/GP-Report/APP%20V-1.pdf];
- • ATV – hardware MJPEG decoder (working on ATM network) [http://cmpe.emu.edu.tr/Courses/CMSE403/GP-Report/APP%20V-1.pdf];
- • Canon HF-11 – HD camera (source of HD signals);
- • Panasonic camera – source of analog signals (used to discuss hardware compression of moving images);
- • Sony camera – source of analog signals (used to discuss hardware compression of moving images);
- • Cisco Tandberg C40 – video-conferencing terminal with microphone and two remote-controlled HD cameras [http://www.cisco.com/en/US/prod/collateral/ps7060/ps11304/ps11312/ps11332/data_sheet_c78-628593.pdf];
- • Two Samsung Smart TVs – used for receiving audiovisual signals (both original and those subjected to compression and decompression processes);
- • Popcorn Hour A110 – HD set-top box [http://www.humanmedia.pl/A110.html];
- • IP-BOX 9000 HD tuner (connected to satellite antenna and digital terrestrial television antenna);
- • Telephone exchange – allowing for construction of simple telephone networks;
- • Yamaha RX767 amplifier [http://europe.yamaha.com/en/products/audio-visual/av-receivers-amps/rx-v767__g/?mode=model];
- • Tonsil sound system (Aktiv and Fiesta);
- • Samsung BD-D6900 – 3D Blu-ray player [http://www.samsung.com/pl/consumer/tv-audio-video/blu-ray/blu-ray-disc-players/BD-D6900/EN];
- • Cisco IP phones;
- • Ethernet routers and switches (mainly from Cisco 2600 and 2800 as well as Cisco Catalyst 3750 series) – used to build computer networks for experiments (including VoIP interfaces);
- • Cisco LS1010 ATM switches;
- • 15 Lenovo ThinkCentre M900 personal computers (with Windows 10 and Linux Ubuntu 16.04 operating systems installed).
| Did you know...?
Fascinating facts that are related to the practical aspects that are presented in the laboratory:
- • Interactive communication involving humans should be conducted with delays of less than 300 ms in both directions. In the case of longer delays, we experience greater discomfort due to the waiting times (such as waiting for a response from a conversation partner during a video conference). This is why the proper configuration of the transmission medium (often computer networks) is so important.
- • Geostationary satellites “hang” at approximately 36,000 km above the Earth’s surface. The satellite latency that is associated with their use is more than a quarter of a second, thus making interactive communication challenging.
- • An uncompressed stream of moving images with a spatial resolution of 1920 by 1080 pixels and a frame rate of 30 frames per second would require a bandwidth of approximately 1500 Mb/s; hence, multimedia information stream compression is necessary. Complex algorithms are used; without sufficient computational power, compression and decompression can be time-consuming processes.
- • The process of compressing moving images is typically much more computationally intensive than the process of decompression. This is due to the detection of motion between successive frames, often resulting in hardware-based image-compression devices.
- • In multimedia-data transmission, network protocols that ensure data reliability are often less useful than those protocols that offer no such guarantees. This is because, in the event of data loss in a computer network, reliable protocols will retransmit the lost data. This causes temporary interruptions in transmissions and significant latency increases (things that humans perceive as being worse than minor data losses in communication).
- • The delay in communications over the Internet (e.g., Skype) is greater than it is in communications over traditional fixed-line telephone networks. This is, in part, due to packet-based data transmission and the coexistence of various types of transmissions in a single network medium.
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