• Dolby Digital 5.1
    The Standard for Digital Sound

    The established standard for home theater, broadcast, and cinema surround sound, Dolby Digital 5.1 has redefined the entertainment experience for audiences around the world. At the movies and in your home, Dolby Digital makes true-to-life soundscapes possible.

    Dolby Digital Benefits

    • A Global Standard

      Every DVD worldwide and all HD broadcasts in the United States use Dolby® Digital (also known as AC-3). Dolby Digital 5.1 has evolved into Dolby Digital Plus, delivering up to 7.1 channels of surround sound in devices ranging from TVs to mobile phones.

    • 5.1 Multichannel Sound

      With 5.1 channels of high-quality audio, Dolby Digital places you in the center of the action. It expands the left and right traditional stereo channels to deliver an enveloping 360 degrees of sound.

    • Cinema, TV, DVDs, and Games

      The same audio technology that revolutionized the cinema enables the sound in all DVDs and US HDTV broadcasts. Even many video games feature Dolby Digital surround sound.

    • Automatic Stereo Version

      Dolby Digital automatically provides a stereo version of the audio tracks so your favorite movies, TV shows, and other entertainment will sound great on any device.

    • Compatible with the Future

      As new audio formats like Dolby Digital Plus™ appear, you can be sure that your Dolby Digital content will remain compatible for years to come.

    Efficient 5.1 Sound

    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.

    Encoding and Decoding

    Dolby Digital operates in a world of ones and zeroes—digital information. Since the audio we hear consists of analog waveforms, not ones and zeroes, the first step in the process of creating a Dolby Digital audio track is to convert the original analog signal into digital information. This process is called encoding.

    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.

    By retaining the important parts of the audio track and eliminating redundant data, Dolby Digital delivers excellent multichannel sound at low data rates.

    The distribution of Dolby Digital audio can take many forms: a film print, a DVD, a television broadcast, a download. Once distributed, the compressed audio needs decoding.

    At the cinema, this decoding occurs in an audio processor, while in your home it can take place in a DVD player, a set-top box, a game console, or another familiar piece of equipment.

    To ensure consistent playback regardless of your specific setup, Dolby Digital uses something called metadata.

    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 Role of Each Channel in 5.1 Sound

    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.

    Dolby Digital Plus: Surround Sound Anywhere, Everywhere

    Dolby Digital Plus delivers a definitive surround sound experience for all your devices from home theaters to smartphones.

    Dolby Technology Codecs

    If your product doesn't play back audio content encoded with Dolby technologies, you'll need to purchase playback software from our partners.

    Dolby Digital for Professionals

    Dolby Digital delivers up to 5.1 discrete channels of high-quality surround sound for broadcasting, home theater, cinema, PC, online streaming, and video game programming.

    Content Creators

    Supported in cinemas and home theaters around the world, Dolby Digital lets you immerse audiences everywhere in your work.

    Broadcasters

    For satellite, cable, and terrestrial HD broadcasts, Dolby Digital provides outstanding audio and unmatched compatibility.

    Distributors and Exhibitors

    Dolby Digital continues to be the world's most popular digital audio format for movies.

    Dolby Digital Specifications

    Channels

    1.0 to 5.1, discrete

    DVD data rate, 5.1-channel audio

    384 or 448 kbps

    Blu-ray Disc data rate, 5.1-channel audio

    640 kbps

    Supports Dolby metadata

    Yes

    Connections

    S/PDIF, HDMI®, IEEE 1394

    Mixing/streaming capabilities

    Yes

    Dolby Metadata Parameters

    Metadata Parameter



    Informational



    Control

    Dialogue level

    Channel mode

    LFE channel

    Bitstream mode

    Line mode compression

    RF mode compression

    RF overmodulation protection

    Center downmix level

    Surround downmix level

    Dolby Surround mode

    Audio production information

    Mix level

    Room type

    Copyright bit

    Original bitstream

    Preferred stereo downmix

    Lt/Rt Center downmix level

    Lt/Rt Surround downmix level

    Lo/Ro Center downmix level

    Lo/Ro Surround downmix level

    Dolby Digital Surround EX™ mode

    A/D converter type

    DC filter

    Lowpass filter

    LFE lowpass filter

    Surround 3 dB attenuation

    Surround phase shift