A programmable Digital Signal Processor (DSP) is said to be the key to a new feature that could make video rewinding all but obsolete.
Known as “automatic digesting,” the new feature enables Digital Video Recorders (DVRs) to pick highlights off recorded video by locating certain visual and audio cues. Viewers simply scroll through a contents page — much as they would on a commercial DVD movie — to find the scenes they want. The feature can be used on all kinds of homemade video recordings.
Developed by engineers at Hitachi, the new feature makes heavy use of programmable Digital Signal Processing. Using pre-programmed software code, it searches through recorded signals for particular audio and video characteristics. In a recorded sporting event, for example, it looks for a rise in the noise level or the sudden movement in a camera image that might be associated with a goal, touchdown or home run. Hitachi engineers pre-programmed the key characteristics for thousands of such potential highlights for sports, news and personal events, in hopes of eliminating the common practices of rewinding and fast-forwarding through recordings.
To make that happen, Hitachi engineers employed a DSP that incorporates audio and video interfaces, as well as programmability. “The system is looking for a sudden jump in audio or a quick jerk of the camera, so those interfaces are critical,” notes Paul Wheeler, an engineering manager for Analog Devices Inc., which provided its Blackfin ADSP-BF531 processor for DVR. Wheeler says the ADSP-BF531 was also key because it provided 400-MHz speed and relative low cost to make the automatic digesting feature possible.
“They could have used a low-performance part, but then it would have taken too much processing time, and customers would have ended up not using the feature,” Wheeler says. He adds that the Blackfin processor costs $4.95, about half the cost of a similarly endowed processor of two years ago.
Programmability, he also says, was significant because it enabled Hitachi engineers to make changes in future editions of the feature.
“For a new feature like the automatic digest, you want to keep refining your algorithms,” he says.
The automatic digest feature is available on Hitachi's Wooo D Series of DVRs, which feature up to 1 terabyte of media storage and record in so-called “Hi-Vision,” a Japanese high-definition format.