Editing Dolby Digital (section)

== Channel configurations ==
Although commonly associated with the 5.1 channel configuration, Dolby Digital allows a number of different channel selections. The options are:

* Dolby Digital 1/0 – Mono (center only)
* Dolby Digital 2/0 – 2-channel stereo (left + right), optionally carrying matrixed Dolby Surround
* Dolby Digital 3/0 – 3-channel stereo (left, center, right)
* Dolby Digital 2/1 – 2-channel stereo with mono surround (left, right, surround)
* Dolby Digital 3/1 – 3-channel stereo with mono surround (left, center, right, surround)
* Dolby Digital 2/2 – 4-channel quadraphonic (left, right, left surround, right surround)
* Dolby Digital 3/2 – [[5.1 surround sound|5-channel surround]] (left, center, right, left surround, right surround)

These configurations optionally include the extra [[low-frequency effects]] (LFE) channel, but only if at least three channels are present.<ref>{{cite web |title=Dolby Metadata Guide |url=http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf |website=www.dolby.com |access-date=20 November 2008 |archive-url=https://web.archive.org/web/20081120150119/http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf |archive-date=20 November 2008 |page=17 |language=en }}</ref> The last two with stereo surrounds can optionally use Dolby Digital EX matrix encoding to add an extra Rear Surround channel, indicated via a 2-bit flag.

Many Dolby Digital decoders are equipped with [[downmixing]] to distribute encoded channels to speakers. This includes such functions as playing surround information through the front speakers if surround speakers are unavailable and distributing the [[center channel]] to left and right if no center speaker is available. When outputting to separate equipment over a 2-channel connection, a Dolby Digital decoder can optionally encode the output using Dolby Surround to preserve surround information.

The '.1' in 5.1, 7.1, etc. refers to the LFE channel, which is also a discrete channel.