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The Dolby Broadcast Loudness Meter LM100 is a tool that provides objective, accurate measurements of the subjective loudness of dialogue within broadcast programming.
Dolby Broadcast Loudness Meter LM100
Differences in audio levels between programs, or between programs and commercials, are a major annoyance to TV viewers. However, these differences have proven difficult for broadcasters to measure with conventional methods and equipment. The Dolby® Broadcast Loudness Meter LM100 solves that problem through Dialogue Intelligence™, a revolutionary technology developed specifically to measure the perceived loudness of dialogue.
Research shows that most viewers adjust TV volume to normalize dialogue levels. By analyzing the input signal and measuring program loudness only during the presence of speech, Dialogue Intelligence objectively measures what viewers subjectively experience.
Applications for the Dolby LM100 range from postproduction and quality control to final transmission, program turnaround, and cable headend facilities.
The Dolby LM100 loudness meter can use ITU-R BS.1770-1 and BS.1770-2 as the core measurement algorithm. Users can also select Leq(A) or EBU R128.* The LM100 can also determine the unweighted peak and a range of other information about the signal, including the Loudness Range measurement specified by the EBU.
The Dolby LM100 presents its measurements in an easy-to-understand numerical format. This eliminates the variations in results that multiple operators often find when using VU or PPM meters, neither of which was designed to measure subjective loudness. The unit can simultaneously display the incoming dialogue normalization (dialnorm) value of a Dolby Digital program (or any program within a Dolby E bitstream) for direct comparison to the actual measured value.
A set of user-definable alarms and monitoring functions can inform an operator of input loss, signal clipping, overmodulation (LM100-NTSC version), high or low signal levels, silence, and incorrectly set dialnorm values.
Front- and rear-panel serial interfaces provide capabilities for software updates and the Dolby LM100 software remote application. The remote application will assist users with advanced loudness measurement, logging features, and enhanced error reporting.
The LM100-LTC includes a timecode input, which allows alarm and other signal conditions to be logged to either the internal time-of-day clock or external timecode. The LM100-NTSC includes an RF input specifically for NTSC CATV and "off-air" television measurement applications. Because the RF tuner replaces the linear timecode input in this version, logging is referenced to the internal clock.
* For units manufactured prior to September 2011, Dolby offers a software upgrade option that adds the latest features, including the ITU-R BS.1770-2 algorithm.
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*The NTSC input replaces the LTC input on this version.
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