Content distribution networks
Apr 1, 2009 12:00 PM, By Tom Ohanian
Consider these 10 things when moving files
The media and entertainment industry is in the midst of an enormous transition. Business models are constantly being evaluated, and new services are being offered. Large media conglomerates are implementing media 360 programs, where content is made available on multiple distribution venues (e.g. terrestrial TV, satellite, broadband, mobile, etc.) and devices. IPTV initiatives are well underway, and the worldwide movement for being connected via broadband is progressing rapidly.
Because of these new business initiatives, there is an explosion of digital content, file formats, content transformation, platform-specific packaging and the incessant need to get content to so many places in ever-decreasing amounts of time.
File-based workflows and digital distribution
Figure 1. Comparison of bandwidth efficiency of content distribution network vs. TCP for a 40GB payload
Click to enlarge
To address these new and continually-changing business models, content creators and manufacturers are adopting file-based workflows. Content must be in the proper format, in the proper location, and with proper essence and metadata so that it can be appropriately consumed, regardless of the listening/viewing device being employed. In practice, the media and entertainment industry is well underway in its transition to digital file-based acquisition, manipulation (editing, etc.) and distribution strategies. An ever-increasing amount of digital files are being generated, packaged and distributed, and much of this electronic distribution is occurring using the open Internet.
Because time is a huge factor in being able to generate and distribute files, file transfer protocols and file acceleration methods are being examined and adopted. It is important to understand how file transfer methods operate and what functionality to be mindful of when researching methods to move files within a digital media distribution strategy.
Moving files?
Digital files, especially large digital media files like HD ones, need to move in the most efficient way possible. WAN optimization technology can help, but file acceleration alone does not solve the problem. There are many other components that should be considered.
Files must be secure, the integrity of the data has to be maintained, assets must be tracked and verified that they were sent and received, and a variety of integration points with editing, transcoding and playout systems must be supported.
With all these moving parts to think about when developing a digital media distribution strategy, the following checklist should be considered before moving forward:
Figure 2. FTP vs. content distribution network on 100Mb/s network
Click to enlarge
- File acceleration techniques
There are two fundamental approaches to WAN acceleration. One technique is to minimize data via compression, and the other is to minimize round-trip delays that are caused by network latency. (See Figure 1 and Figure 2.) With compression, users will see improvements when network capacity is relatively small. Even so, network latency is the main issue for large pipes. Further, digital media files typically do not benefit from additionaldata compression techniques.
There are generic data compression techniques and data-specific techniques. On the generic compression side, Huffman encoding is typically used for text files. Run-length encoding is used for data exhibiting consistent patterns. Network comparisons, or differential transfers, is another method that can reduce the amount of data needing to be sent because it first checks to see what already exists on the target side.
- Industry standard client connectivity
By using standard methods of connecting clients to clients, clients to server, and server to server, the benefits of IT commodity extend beyond the distribution system. Other systems and applications are able to use a standard, common interface.
- Data confidentiality and data integrity
Data confidentiality refers to the securing of content so that it is not at risk of being pirated or “snooped” in transit. This differs from data integrity, which refers to the verification that the actual data that is sent is identical to the data received. This is especially important for corporate governance requirements.
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