Video Over IP Applications
Video over IP applications have soared in popularity over the last five years. Companies have increased their video conferencing usage as a means to reduce travel expenses, speed up the lead time needed to hold critical meetings, and offer investors access to high level board meetings. Traditional phone service providers are rushing to provide video services as a way of locking in customers and increasing revenues. Cable TV operators have been steadily upgrading their analog systems to offer consumers enhanced digital services. All of these applications focus on delivering digital video content over data services. As these video services evolve from luxuries and novelties to commodities and everyday expectations, video IP equipment vendors and service providers are scrambling to establish themselves as the dominant players in this maturing industry.
IP video applications have struggled with two main challenges for high quality video experience: the ability to deliver the high bandwidth at an acceptable price and overcoming the imperfect world of IP networks. Relatively inexpensive DSL and cable modem services have helped to solve some of the high bandwidth issues, but typically the achieved bandwidth is much lower than the published access data rate. New techniques lower the bandwidth requirements needed for quality transmission and compression methods are two ways currently being developed to address the bandwidth issue.
In addition to high bandwidth, high quality video must overcome the imperfect world of IP networks. There is another very important factor that must be designed for: the imperfect world of IP networks. Network impairments are expected in IP communications. Network delays, dropped packets, traffic congestion, reordered packets, fragmented packets, and duplicated packets are all facts of life in IP communications. Many higher level protocols such as TCP are designed with error correction mechanisms to ensure that data is moved nearly error free from point to point. TCP dictates that endpoints resend packets when errors are encountered, and application delays may incur because of this, but most likely the correct information will eventually be delivered and the application can operate as it should. Video streaming and other real time IP applications can't afford the overhead time associated with error correction protocols, and typically rely on UDP protocols. VoIP also uses UDP protocols, and is subject to similar network impairment problems. Although it can be an annoying experience to use VoIP service with poor quality, humans can negotiate their own 'error correction'. "Sorry, I didn't hear that last statement. Could you repeat that?" IP video does not have the luxury of higher level or human intervention error correction. It is subject to the most demanding endpoint of all; the human eye and human visual experience.
If uncorrected, dropped packets can cause 'skips' in the experienced video. Variable network delays (jitter) can cause the video to appear 'jerky' and 'jumpy'. Data errors can significantly delay video quality. The onus now lays on the IP video equipment vendors to design recovery algorithms that can operate in this environment to reassemble packets into a satisfactory video experience for the end user.
PacketStorm Communications manufactures the equipment needed to test IP video applications and equipment:
Repeatable network impairment control:
The PacketStorm network emulators provide precise control and repeatability of the various conditions that will be encountered in WAN and LAN data communications networks. Development engineers and QA personal can now have a controlled emulated infrastructure to develop and test IP video signal recovery mechanisms, thus ensuring that their equipment will provide a positive experience for the end users. Service providers can also emulate their networks to gauge acceptable limits for error conditions and then set network alarm thresholds based on these values.
Configuring QoS setting and internal routing equipment configuration:
The PacketStorm systems provide adjustable QoS capabilities and emulate router queuing algorithms that can provide valuable information for dictating procedures that mandate how internal routing devices should be configured.
Determining the required bandwidth needed:
PacketStorm network emulators offer the capability to throttle the available connection bandwidth so that it is possible to determine the minimum required rates for acceptable video transmissions for various compression algorithms.