Phil Kurz /
11.10.2009 02:58 PM
Smart rendering plays important role in contributing news stories via IP networks

News contribution from the field via broadband IP networks is a critical component of the new file-based workflows many newsrooms are adopting with the aim of putting more feet on the street and increasing daily story count.

But for broadband IP to succeed as a viable contribution technology — especially when it comes to HD news stories — there is a limit to how long story submission can take. According to Bitcentral CEO Fred Fourcher, anything under 15 minutes is acceptable, but beyond that, impatience reaches the breaking point and broadband IP becomes unattractive.

A variety of factors, including available bandwidth (1Mb/s for T1 vs. 20Mb/s digital ENG microwave), video format (16:9 SD, 720p HD or 1080i HD), recording format and encoding factors all contribute to the time required to transmit an edited story via broadband.

A somewhat less well-known but equally important factor is the presence of a “smart rendering” feature as part of any nonlinear editor used in the field on a laptop computer, Fourcher says.

Smart rendering minimizes the amount of rerendering that must be done by restricting the effort to only those frames needed to make up a cut. While a quad-core-based computer plugged into the wall back at the TV station should be able to rerender HD in close to real time, the laptops reporters use in the field aren’t likely powerful enough to accomplish that feat. In fact, it can take many multiples of real time to encode on a laptop, Fourcher says.

“When you see these editors do a smart render, they literally march through as fast as they read the video and then hit a frame with a cut,” he says. “They’ll stop a minute, stitch it together and continue along.”

Several nonlinear editors, including Apple Final Cut Pro with a special plug-in, Grass Valley EDIUS, Sony Vegas and Adobe Premiere Pro, include smart rendering features that identify a cut and splice together the MPEG-2 GOP structure. According to Fourcher, smart rendering currently is restricted to MPEG-2 files; however, several vendors say they have plans to offer the feature supporting MPEG-4 H.264.

Editor’s note: Fred Fourcher delivered a presentation at the recently completed SMPTE Conference and Expo on the topic of HD news contribution via IP networks. To listen to Fourcher describe the issues involved, check out the audio podcasts on the Broadcast Engineering Web site.

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