College】 【weak corporate video conferencing systems in three popular techniques --- Power By 【China】 weak home network.

According to market consulting firm WinterGreenResearch <br> forecasts, unified communications market development cycle is about to enter the healthy growth and rapid application stage. .2008, the market may achieve 15% growth in 2009 will grow by 30%. .The video in the enterprise deployment of unified communications will become an absolute dark horse. .<BR> Traditional enterprise video technologies include: MCU, H.323, Frame Relay, IP bearer network-based video applications, will push more features to the user's face. .But to successfully use these features, users need to focus on some new technology to give more attention. .<BR> <BR> An LPR: a steady video stream <BR> <BR> unified communications and video applications to enable enterprises to voice, data synchronization in the IP bearer network to transmit video data in the form of packets, which inevitably .Network packet loss problem encountered. .Packet loss will cause the video image mosaic; image local deformation, the screen refresh or flicker frequency; video and audio are not synchronized; frame rate drop, and image still other issues. .In the unified communications environment, as video, voice and data streams are transmitted simultaneously, thus packet loss will result in the overall audio distortion, interruption or intermittent noise, and the decline in the quality of content presentation, such as slides or fuzzy distortion .speed slows down page. .These issues will greatly influence the application of the user experience. .If the network packet loss rate is too large or too frequent, will cause excessive delay video communications, and even cause traffic disruption. .<BR> <BR> Packet loss is network congestion by the internal or external network priority traffic such as causes of conflict. .To avoid packet loss, we must first determine the bearer network packet loss rate, packet loss distribution over time, and video call performance of the various terminals and devices. .<BR> <BR> LPR (loss recovery) technologies to solve the current problem of video transmission loss one of the most effective way, based on the technology developed by Polycom, a new algorithm, its purpose is to protect IP video calls from .the impact of network packet loss. .In fact, LPR uses forward error correction is a (FEC) method implementation of covered packet loss mechanism. .Issued by the sender's data flow system to add redundant data, so that the receiver system to detect and correct errors without having to request the sender to resend the missing information systems. .This will have no need to wait for network transmission capacity of error correction, making the FEC is very suitable for real time communications, such as television broadcasting, IP telephony and IP video conferencing. .<BR> <BR> LPR works is ongoing through the video terminal to monitor all incoming call packet loss information. .Once packet loss is detected, the terminal will use three methods to ensure call quality: packet loss recovery (LPR), dynamic bandwidth allocation (DBA), as well as in the case do not support LPR, the use of traditional video error concealment ( .PVEC) technology. .<BR> <BR> Unlike most of the error concealment algorithm only involved in receiving or avoiding loss of information in a systematic way, LPR will be involved at all levels of the video call system, part of the call by temporarily assigned to a data channel bandwidth, ., which is used to send data to the receiver FEC to play a role. .Packet loss in network transmission occurs when a loop through the above, LPR will increase or decrease the size of FEC data channel, until you find the FEC data channel must be allocated to the minimum bandwidth, allowing the receiving system can recover all lost packets .. .<BR> <BR> When FEC data channel is larger than the standard value, the system will detect whether repeated FEC can reduce the size of the data channel, so as to audio, video and content data available to the call to provide more bandwidth. .Because LPR only packet loss is detected only when the occupied bandwidth, a feature that makes the LPR is ideal for random packet loss or sudden environment. .<BR> <BR> Packet loss rate against a relatively fixed network environment, dynamic bandwidth allocation (DBA) functions can be matched with the LPR. .DBA is an algorithm that can automatically during a video call, and dynamically adjust the video bit rate, to eliminate or avoid packet loss. .For example, in a 384kbps test video call to a stable at 10% packet loss rate, DBA will be reduced by about 10% of the video bit rate, from 320kbps down 288kbps or so, and then re-sampled signals, see if there is packet loss .phenomenon. .If necessary, DBA can further reduce the video bit rate, until no longer appear in seconds until the packet loss. .<BR> <BR> In reducing the rate, if the measured packet loss is temporary, DBA, DBA will gradually increase the video bit rate. .Conversely, if the DBA detects packet loss sustained, it is no longer adjust the video bit rate, but the call continue. .Therefore DBA applies to excessive use of network problems caused by packet loss or throughput environment. .<BR> <BR> The parties involved in the system calls the case do not support LPR, you can use the Video Error Concealment (PVEC) function. .PVEC is a quality of service for IP video (QoS) algorithms, which can be caused by the impact of packet loss compensation. .It is through the use of adjacent macro blocks, before and after the frame out of frame to estimate the content of the current video frame. .And LPR to recover lost packets and packet loss to avoid technical differences DBA, PVEC cover the role of the impact of packet loss. .<BR> <BR> On this basis, LPR allows the user to the error rate is high in IP networks (DSL, cable, satellite, high conflict, LAN / WAN, etc.) for high-quality video calls without the need bear lost .package impact. .Rate of ongoing calls by temporary adjustments, LPR can protect against short-term network video call problems. .Once the network problem solving, LPR will initiate the call rate or under the current bandwidth availability, automatically call back rate to the highest level. .This makes the network bandwidth can be fully utilized to achieve the recovery of lost data packets and transmission of real-time reconstruction of the smooth flow of audio and video data, eliminate waiting, intermittent, noise, confusion and other problems or information, but can reduce the dynamic jitter buffer .Spatial and related delays. .<BR> <BR> But the use of LPR will generate FEC channel bandwidth, which used video calls reduced their available bandwidth. .In the case of low-connection rates may cause a temporary reduction or resolution of the lower frame rate. .<BR> <BR> Two restore the scene: the experience of face to face <BR> <BR> clear video images for the user, the real requirement is no upper limit, which directly led to the Cisco TelePresence, Nortel and HP Halo telepresence .birth, as represented by these products, companies will use the ultra-high-definition video applications, technology, experience the effect of restoring the site. .<BR> <BR> With traditional video conferencing systems, these products are the most obvious feature is its ultra high-definition resolution. .According to reports, three pieces of telepresence using HD plasma display, each screen resolution up to 1080 × 1080p, than the current international standard HD resolution (1280 × 720p) twice, is 10 times the resolution of ordinary TV .. .6 people can provide "virtual meeting" telepresence 3000, required every plasma screen in the 2 ~ 4Mbps bandwidth between the 3 screens require a total of about 10Mbps bandwidth, ADSL has been impossible to carry the ordinary and therefore require special .Dedicated access or fiber access. .Ability to meet the ultra-high performance hi-fi images, and ergonomic design environment, so that Cisco TelePresence system can communicate in real performance of every detail, such as "clear white of the eye, skin, the hairs, and the communication of .strategy with a shy look, "and so on. .It is reported that net price is really 7.9 ~ $ 299,000, has been in AMD, Pepsi, GE and other large enterprises in the applications. .<BR> <BR> Emphasize HP's Halo studio system for enterprise remote analog face to face business meetings. .Connected by Halo, Halo studio support for each row of six people at a table, the second row of three to six and a maximum of 12 meetings of scale. .Each studio has three plasma displays, participants can see and I am the same size image. .In addition, participants can also use a plasma display mounted above the screen 50-inch collaboration with other Halo studios in its notebook computers to share files and data. .Photo Studio also includes a high-definition camera, the table can be used to capture and display the items on display in the collaboration, true color rendering, shading and nuance. .Equipped with a telephone for participants to work with Halo outdoor personnel. .Studio is equipped with broadcast-quality audio and lighting facilities, participants can use the simple on-screen user interface, start by clicking the mouse collaboration. .A complex software control system will ensure that all Halo studio easily and seamlessly work together. .<BR> <BR> HP Halo high-bandwidth, dedicated video switching independent network connection to provide full-motion video experience HVEN, making it among the world's Halo studio audio or video delay is not perceived by people. .24 × 7 to ensure all-weather connectivity, HP offers including: network operation and management, remote diagnosis and troubleshooting, security, equipment warranty and ongoing maintenance and repair services. .Halo studio users do not manage the operation and maintenance, <BR> <BR> HP has been present in 18 countries around the world more than 60 such workshops. .<BR> <BR> According to reports, HP Halo Collaboration Studios set of the room price was 39.9 million dollars, plus 24 thousand per month to 2.5 million in services. .At present, Halo users have included DreamWorks, Novartis, AIG Financial Products, BHP Billiton (BHP Billiton), Canon and other famous companies. .<BR> <BR> Nortel telepresence (Telepresence) communication system is fully reflects the "show" the mean, life-size screen, high definition video effects and StereoSurround sound seamless, collaborative display of multimedia content, videos and more .Point control technology (MCU) recording, archiving, streaming and HD support. .This is a more optimized experience can be customized, from small meetings of two people to be able to accommodate 28 people in the large conference room, users can achieve high definition video communications, and also show the film seamlessly, data tables, and other format files .content, collaboration, the equivalent of full virtualization of the people in the room to complete all activities. .And the whole process so far based entirely on meeting off-site environments. .<BR> <BR> Telepresence system, the modular design features highlighted; studio level lighting; professional acoustic treatment; no remote control and interactive control; hidden camera; microphone and PA system. .Every element is designed to integrate, fully embodies the technology seamless and transparent, and the organic integration of the physical environment to form a unified professional audio and video conference environment. .In addition to not shake hands, almost face to face meetings have been no different. .<BR> <BR> Nortel is really the standard turnkey far, Nortel provided a comprehensive set of services. .Including site survey, network assessment, project management, opening services, 7 × 24 hour support, and specifically for high-definition system MNOC multimedia services, both all-weather meeting appointment, proactive remote monitoring, meeting to establish, confirm and report monthly remote services. .<BR> <BR> Three QoS: high-quality transport protection <BR> <BR> application of QoS in the network technology is not new, but the video QoS bearer network streaming media technology is a new hot spot. .<BR> <BR> Business-to-video technology innovation is the pursuit of the application of streaming media technology to become mainstream. .Streaming real-time playback, there are strict requirements, require a specific time interval to decode a particular unit of data display. .Streaming media business development at present there are some problems, such as playing media files, pause, mosaic and so on, there are a large number of users to access popular content sudden server processing difficulties, etc., these problems are related to the QoS of streaming media to ensure .. .<BR> <BR> Enterprise Video used in the most critical business, but also with voice, data synchronization, transmission, network transmission quality and therefore have higher requirements. .QoS needs of streaming media to solve two problems, bandwidth and delay jitter. .<BR> <BR> We all know, video and voice networks such as unified communications is one of the applications the bandwidth consumption. .Bandwidth limitations on the one hand affect the quality of video playback; the other hand, consumption of large bandwidth streaming media applications, will work with other businesses in the network compete for bandwidth, which of these affect the normal operation of the business. .<BR> <BR> In addition, IP network for video data, store and forward mechanism to determine the packet delay and jitter is inevitable, so the streaming media transmission, the end to end delay should be controlled within a certain range. .Streaming Media QoS using advanced video coding scheme, video data compression to improve efficiency, as much as possible to eliminate redundant information in the video, making the source code as little as possible the amount of data output, the minimum network bandwidth to accommodate the situation .. .Meanwhile, video quality can be graded to provide a flexible adaptation to maximize the dynamic characteristics of the network as far as possible to provide users with better video quality. .<BR> <BR> Scalable coding techniques to increase the coding output bit stream to adapt to dynamic network bandwidth flexibility, multimedia data compression coding into multiple streams. .One can be independent decoding, known as the base layer bit stream, the other is called the enhancement layer stream. .They can not be decoded separately, but only with the base layer and enhancement layer before it is combined with the decoder, used to improve the viewing experience. .<BR>.