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Dolby's File-Based Approach to Noise

Dolby Laboratories' latest product aimed at improving the audio experience for television viewers is a file-based system that corrects loudness problems on a compressed piece of content. Called the DP600 Program Optimizer, it works without having to decode and re-encode the audio.

Set to be introduced at NAB, the DP600 is described by San Francisco-based Dolby as the “world's first intelligent file-based audio-loudness-analysis-and-correction system.” It is based on the same technology used in Dolby's LM100 Broadcast Loudness Meter, and it focuses on maintaining a consistent volume level within television programming to avoid the sudden increases or decreases that can annoy viewers.

“When people surf channels, they often use the volume control to normalize speech levels,” says Jeff Riedmiller, professional broadcast product manager for Dolby. “You don't want the TV shouting at you or whispering at you. That's a very important aspect of the experience.”

While the LM100 is only a measure ment device, the DP600 corrects audio problems and is designed to work in tapeless broadcast environments that use servers to store programming in compressed form. The product is compatible with most common media file formats and will automatically normalize the loudness of file-based programming and commercials without impacting the original dynamic range.

“It's targeted at file-based work­flows,” says Riedmiller. “Whether it's a cable company doing VOD [video-on-demand] or digital-ad insertion, or a broadcaster playing programs off a server, this technology will take any of those file formats, peel it apart, and go in and analyze the audio essence of those files.”

Programs can be normalized by the DP600 in two ways: by correcting their associated metadata values to reflect the actual audio signal that was measured in the file or by scaling the audio signal itself to a target loudness level.

The DP600 system becomes available late this year and will sell for $16,800. An enhanced version, at $24,000, provides faster–than–real-time file-based encoding and decoding of Dolby Digital, Dolby Digital Plus and Dolby E content, as well as efficient transcoding between the three audio formats.

Premium cable network Starz was an early adopter of the LM100 and will test the DP600 later this spring. Since Starz uses servers to play out multiple networks, the DP600's ability to correct audio problems without adding another decoding/encoding step in the transmission chain makes a lot of sense, says Starz Manager of Post Production Sean Richardson.

“We like being able to have some correction done in the file domain,” says Richardson, adding that the DP600's Dolby E transcoding option is an “incredibly helpful” feature.