The Problem
Volume level inconsistencies have been a serious, global problem in television for many years. Television audiences around the world encounter vast differences in the perceived volume level of content each and every day. Whether it is a simple channel change or switching sources such as from a DVD to TV, television viewers are frequently required to make volume adjustments via their remote control.
Dolby has invested many years researching volume level problems in order to develop effective solutions. Dolby's first major solution to resolve volume level issues is a metadata concept featured in Dolby Digital and Dolby Digital Plus. While Dolby audio metadata is well suited to resolving volume level issues (it provides content providers, broadcasters, and operators with a tool called "dialog normalization"), global volume level challenges remain on broadcast systems where Dolby audio formats are not being used. Such systems have no built-in mechanisms such as metadata to manage volume levels across channels, or content. In addition, significant level differences also occur due to level differences between analog and digital transmission or between different input sources connected to a TV set.
Dolby's Innovative Solution
Recognizing the widespread and intrusive issues related to volume variations, Dolby has leveraged its extensive understanding of audio and years of research to create Dolby Volume, the next generation of volume control technology for televisions. Dolby Volume features a new, groundbreaking volume leveling solution that, when integrated into televisions, provides a unique solution that finally overcomes the volume level differences in all content experienced through television sets. By continually monitoring and adjusting the perceived volume level of the audio, Dolby Volume allows any audio source played through a TV's speakers to match a desired target playback level set by the user. The new volume control technology offered in Dolby Volume works regardless of the audio format (such as analog, digital, or low-bit-rate coded). While Dolby Volume's volume leveling function resolves loudness differences in a single-ended way (that is, without pre-processing or metadata), it can also take advantage of and benefit from Dolby's powerful audio metadata when available and provide an even higher quality volume control solution.
How does it Work?
Dolby Volume is comprised of a suite of complementary volume level processing technologies designed to work together seamlessly and provides a complete high-quality audio solution. Unlike previous attempts which have addressed the problem by using standard audio compressors or automatic gain controls (AGCs), Dolby Volume's uniqueness lies in the fact that for the first time the measurement, analysis, and control of the volume level of audio is performed using a perceptual processing engine built on an advanced psychoacoustic model of human hearing. This engine simulates, in real-time, the complex, non-linear mechanisms through which humans perceive loudness and organize sound. With the guidance of this perceptual engine, Dolby Volume knows not only how and when to process the audio but, equally important, when not to process the audio. As a result, Dolby Volume is a new approach uniquely capable of reproducing any audio signal, at any desired playback level set by the user using a standard volume controller, free of any of the audio artifacts (like pumping and breathing) introduced by the previous standard compressor or AGC solutions. Dolby Volume achieves this high-quality and artifact-free performance by combining two patented features derived from its powerful analysis and processing engine:
