At its core, Dolby Digital technology represents a very efficient way for movie studios, television networks, and other content providers to compress the size of multichannel audio files without impairing the sound quality. The smaller the file, the easier it is to distribute. With Dolby Digital, it's possible to include a full 5.1-channel audio mix on a film print or a DVD, or as part of a TV broadcast. This expands the creative palette for artists, and allows those of us in the audience to experience greater realism and excitement.
But rather than simply converting waveforms to numbers blindly, Dolby Digital analyzes the original audio and intelligently determines what parts of the audio track are important to keep and what parts you're less likely to hear.
Metadata is a set of instructions created during programming production and carried in the Dolby Digital bitstream. It ensures you enjoy a high-quality audio experience, whether you're listening on a mono, stereo, or 5.1-channel system, and also lets content creators offer additional features so you have more control over playback.
The channels in a 5.1 audio mix serve distinct purposes. The three front channels (Left, Center, and Right) provide crisp, clean dialogue and accurate placement of onscreen sounds. The twin surround channels (Left Surround and Right Surround) create the sense of being in the middle of the action.
The Low-Frequency Effects (LFE) channel delivers deep, powerful bass effects that can be felt as well as heard. As it needs only about one-tenth the bandwidth of each of the other channels, the LFE channel is referred to as a ".1" channel.
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