Adobe's Emerging Rich Media Ecosystem, Part 2: Developing Live and Video on Demand Streaming Media Applications
The Cisco Content Delivery System
Figure 8: Cisco Content Delivery System. Any Stream to Any Screen with Adobe Flash Streaming Enhancements to the Cisco CDS
Don't forget anything that encourages more video (especially high quality video) is good for Cisco, because it, high quality video, needs a huge amount of bandwidth.
The CDS platform provides additional benefits for the hosting and distribution of Flash Player-compatible video content and services, including content and service routing, dynamic hierarchical caching, load balancing, failover protection, IP multicast extensions, unified management tools, and end-to-end quality-of-service (QoS) support.
Attempts to display media on computers date back to the earliest days of computing, in the mid-20th century. However, little progress was made for several decades, due primarily to the high cost and limited capabilities of computer hardware.
During the late 1980s, consumer-grade computers became powerful enough to display various media. The primary technical issues with streaming were:
- Having enough CPU power and bus bandwidth to support the required data rates
- Creating low-latency interrupt paths in the OS to prevent buffer underrun
However, computer networks were still limited, and media was usually delivered over non-streaming channels, such as CD-ROMs.
The late 1990s saw:
- Greater network bandwidth, especially in the last mile
- Increased access to networks, especially the Internet
- Use of standard protocols and formats, such as TCP/IP, HTTP, and HTML
- Commercialization of the Internet
These advances in computer networking, combined with powerful home computers and modern operating systems, made streaming media practical and affordable for ordinary consumers. Stand-alone Internet radio devices are offering listeners a "no-computer" option for listening to audio streams.
In general, multimedia content is large, so media storage and transmission costs are still significant; to offset this somewhat, media is generally compressed for both storage and streaming.
Links to representative streaming video application such as
- Videos in clinical medicine
- Video and audio courses
- Video Streaming & Email Marketing
- Third-party Flash video streaming hosting
are included in the References section.
And, video can help you convey the strength and achievements of your organization and leadership team to customers, partners, vendors, investors, employees, and the media. In an era of transparency and short attention spans, online video provides a personal, emotional experience that connects the presenter to your audience for the length of your presentation. On a video platform, you also can integrate other multimedia such as Flash animation, images, and graphics to increase the comprehension and retention of your message.
Finally, research in streaming media is ongoing. Representative research can be found at the Journal of Multimedia, a publication appropriate for readers with a background in advanced mathematics.
Transmitting streaming video over a wireless communications channel is, in and of itself, a challenging proposition. Wireless communications, in general, are prone to inducing errors into the digital bit stream because of interference, weak signals, multipath fading, crowded air waves, and any number of other factors. Overcoming these conditions is challenging enough, but today's video compression techniques make matters worse. To fit a streaming video application into the wireless bandwidth that's available today, compression standards like MPEG-4 and H.264 have become a way of life. These and other compression techniques help to deliver the video bit stream, but they often work at cross-purposes to the quality of the video image displayed on the terminal device.
The problem becomes acute because the various compression techniques remove much of the redundancy from a typical video bit stream. The logic behind most video compression methods is that the currently displayed frame is the basis for the frames following it.
Wireless communications works fine until an error is encountered in the bit stream. Because of the predictive nature of compression techniques, any error in an image could be propagated through successive frames. This uncontrolled propagation of errors also can cause the video decoder to lose synchronization with the video bit stream, leading to a complete failure of the decoding process. For the viewer, that means a frozen image on the display screen.
Newer compression standards, such as MPEG-4, have taken this phenomenon into account and a number of techniques are now built into the compression standards to overcome part of the problem. These techniques, which are known as error resilience tools, allow for the detection, containment, and concealment of errors in a video bit stream.
Of course, everything comes with a price and the price of error concealment is processor cycles.
Further exacerbating this problem is the fact that errors in wireless communications typically occur in bursts. As a result, the processor cycles devoted to error concealment would rise and fall sharply, further straining the resources of the terminal device at those times when the bit stream is prone to extensive errors.
New multimedia applications will continue to strain the resources of wireless devices. Any headroom designed into a device platform today will be quickly absorbed by new multimedia applications tomorrow.
The obvious solution: Design your applications conservatively.
Page 5 of 7