IP video distribution
Dec 1, 2009 12:00 PM, By Mark Hershey
With the industry's dynamic transformation to file vs. tape-based operations, solutions for effectively ingesting, managing and distributing digital assets are critical to a broadcaster's success. The variables in successfully delivering high-quality video over IP networks are numerous. Bandwidth optimization, compression choices, intrinsic latency, smoothing latency, scalability, integration with broadcast workflows and content delivery network (CDN) integration are just a few. And, while IP-delivered video may have a way to go to equal the experience available through traditional broadcast platforms, a quality Web-based viewing experience can significantly expand a broadcaster's reach, provide channels for potential revenue gain and set the table for success in the new media age.
This article discusses the challenges and solutions involved with the successful delivery of video over IP networks, with a focus on over-the top (OTT) video distribution.
Understand your network requirements
What kind of demands will OTT video — delivered to every conceivable playback device realized or imagined for the future — place on your network? That answer depends on how you respond to two key questions:
First, what is your delivery strategy? That is, what content do you have to offer, and is it live, on-demand or a combination of both?
Second, who is your audience? How many simultaneous viewers and what variety of playback devices do you expect? Which of those devices do you consider strategic to allow you to reach your goals? Are viewers predominately local, or do you have global aspirations?
The key factor that encompasses all of these variables, and that has the most impact on network capacity, can be reduced to one word: scalability — how many viewers, how many different streams and how much is to be stored for online access and playback.
Impact of live streaming
If your needs are simple, packaged systems are available that can encode, deliver and manage your entire Web video presence. (See Figure 1 on page 8.) These systems ingest real-time video and compress it to create and deliver the viewable IP streams in real time. In their simplest form, they create one stream (typically in Windows Media or Adobe Flash Live format) and deliver it to a small number of local users via your in-house media server. Many independent stations started their Internet presence in just this manner, and for a small number of stream types and viewers, this is still practical with little impact on the network and existing Internet connection.
Figure 1. This illustration shows how a streaming media server can simplify the complex workflows often associated with the transformation and delivery of high-definition video over IP and mobile networks.
Select figure to enlarge.
However, with the explosion of interest in video streaming, increases in the number and types of devices used for playback, and a higher expectation to duplicate the video viewing quality of off-air broadcasting, the simple solution is no longer simple and no longer adequate in order to remain competitive.
Reaching out to a diverse online and mobile audience now requires multiple streams of differing characteristics. Where one or two streams sufficed in earlier times, the latest adaptive streaming technologies call for as many as five to seven or more streams from each video program source to serve even a small cross section of possible viewers. This essentially forces either a massive investment in in-house encoder and server resources, or forces an outsource-to-CDN strategy where you create separate uplink streams directed to a content delivery provider that, in turn, distributes your content to users or subscribers.
It remains possible to use a conventional Internet connection for one or two of those CDN uplink feeds, but at the risk of playback quality, reliability and consistency when using any but the most optimized Internet connection. As an alternative, consider using managed, unchallenged uplink feeds from a dedicated IP network service provider. They can guarantee reliable packet delivery to the CDN. Uplink quality is critical, any impairment of this feed affects all viewers everywhere, and recovery for even momentary network hits on the uplink are not as automatic as you might expect.
To enhance uplink performance, consider redundant streams on different networks. High-end media encoders can create multiple streams from the same video encoder, delivered via separate TCP/IP ports connected to different networks. Similarly, most CDNs accept multiple uplink streams and will automatically switch over when faults are detected. Of course, redundancy multiplies the impact on your network and will not be effective in preventing catastrophic outages if the redundant uplinks do not take diverse routes.
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