Dolby DP600 adjusts audio levels inside media files

The new DP600 Program Optimizer to be introduced by Dolby Labs at the NAB convention in late April gives broadcasters more control over audio levels of file-based programming.

The challenge in moving to a non-realtime file-based environment is, until now, the tools were not available to analyze the audio, says Rocky Graham, Dolby Labs director of broadcast products.

The DP600 is in many ways a companion to the LM100 loudness meter that broadcasters have come to rely on to find out whether the audio loudness levels are set properly. Unfortunately, the LM100 can t automatically adjust the levels. The DP600, however, can adjust those levels.

The system takes the video file and analyzes its audio metadata, recalculating the dynamic range parameters and setting the audio levels to the desired level. It also has infinite look-ahead capability so that as more and more programming and commercials sit on a video server it can set all of them to the same level, says Graham.

With more broadcasters and networks embracing server-based storage figuring out to easily normalize audio levels becomes a more pressing issue.

To do a real-time correction is too difficult because the operators ends up riding the gain too fast which compresses the dynamic range, says Graham. And if it s done too slowly abrupt changes in loudness will get through to the viewer.

The faster-than-realtime encoding and decoding capabilities of the DP600 improve that process. Incorrect audio levels have been a problem for a long time, says Graham. And with digital and HD broadcasts becoming more mainstream any problems will become more apparent.

Dolby will also unveil the Cat No. 561 Dolby Digital Plus OEM encoder module, the first Dolby Digital Plus encoder designed for integration into third-party manufacturer’s audio/video products. The Cat. No. 561 gives broadcasters real-time, multistream, and multichannel encoding for Dolby Digital and Dolby Digital Plus formats.

This will help with transcoding equipment because it avoids the full decode and encode cycle, preserving the quality of the material as it goes through the transcoded process, says Graham.