Tuesday, July 21, 2009

Video-Film Production Bandwidth

Video and film production is increasingly a digital process, often with contributions from multiple sources in diverse geographical locations. While "sneaker-net" or postal services can be used to transport content from place to another on tapes and disks, rapid production schedules really cry out for electronic transfer. But how do you do that and what are the costs involved?

The key characteristic of digital transport services is bandwidth. This is the transmission rate in bits per second, although in practical terms it's quoted in Mbps or Gbps. The thing you need to know about bandwidth is that, in general, the higher the bandwidth, the higher the price. I say in general because some newer services, such as Metro Ethernet, can be priced lower than traditional services for the same bandwidth.

How much bandwidth do you need? That depends on how big the data files are that your process generates. Video clips or streaming video intended for watching on Web browsers is orders of magnitude smaller than high definition video intended for digital cinema.

There is also a tradeoff between how fast you need a file delivered and the required bandwidth. If you desire real-time high definition broadcast quality with no compression, you're looking at requirements for fiber optic services in the Gbps category. If you are satisfied with overnight transfer of compressed standard definition video programs of less than an hour's length, you may be able to get by with a much lower cost T1 or bonded T1 line in the Mbps category.

So it comes down to these tradeoffs: real time transfer, say for on-air broadcast, versus file transfers that can take minutes or hours. Also high definition versus standard or even lower grade definition. Finally, uncompressed versus compression by, say, MPEG-2 or MPEG-4.

There are a few standard digital interfaces used in video, film and television broadcast that have been standardized by SMPTE, the Society of Motion Picture and Television Engineers. They are based on the SDI or Serial Digital Interface that is standardized in professional video equipment. The standard definition interface is SD-SDI per SMPTE 259M. This requires a bandwidth of 270 Mbps. The high definition interface is HD-SDI per SMPTE 292M. It requires a bandwidth of 1.485 Gbps. Another emerging standard is dual link HD-SDI or a pair of SMPTE 292M links, standardized in SMPTE 372M. This dual link requires 2.97 Gbps. Finally, SMPTE 424M is a 3G-SDI serial link that also requires 2.97 Gbps.

While these standard signals were developed primarily for interconnecting professional video equipment using coaxial cable, there is now equipment available to transport those SMPTE standard signals over private or leased fiber optic lines over long distances. Studios, production houses and cinemas can be interconnected using equipment such as Optiva cards from Emcore or Ekinops video transport modules.

In addition to the interface hardware you'll need transmission services, most often leased lines. Depending on your location, you may be able to get SONET or Gigabit Ethernet fiber optic line services. If you don't need real-time transmission or are able to use compression to reduce your bandwidth requirements, you may be able to get by with Ethernet over Copper or DS3 service.

What will work best for your application and how much will it cost? Find out by discussing your needs with one of the expert Telarus bandwidth consultants available through our Gigapackets bandwidth service. This is a brokerage service offering services from a dozen or more carriers. It's available free of charge to serious business users.

Click to check pricing and features or get support from a Telarus product specialist.

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