By contrast, modern soundtracks use discrete channels of information. That is, each speaker has a distinct signal that is completely independent of every other channel. This approach is clearly more desirable, since it gives the
There are many
Table 1: Common multichannel modes
Name | # Chs | Matrix/Discrete | Comments |
analog stereo | 2 | Discrete | Found on almost all sources, including |
|
|
| tape decks, tuners, and CD players. |
analog multi- | Discrete | A | |
channel input |
|
| mostly for SACD & |
Dolby Surround | 4 | Matrix | The original matrix decoding system |
Pro Logic |
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| designed to squeeze four channels into |
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|
| two and then retrieve them. |
Dolby Pro | Up to 5.1 | Matrix | An improvement of Dolby’s original |
Logic II |
|
| Pro Logic matrix decoder, Dolby PLII |
|
|
| is designed for 5.1 surround systems. |
Dolby Pro | Up to 7.1 | Matrix | An improvement of Dolby PLII, this |
Logic IIx |
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| version uses the 2ch or 5.1channel |
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|
| source audio to create as many as 7.1 |
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|
| channels (depending on speaker setup) |
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|
| of surround sound. |
Dolby Digital | Discrete | The most common modern digital | |
(formerly |
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| source, used in HDTV, DVD, etc. |
Dolby | 6.1 | Discrete | A 7th channel of discrete information |
Digital EX |
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| was recorded during filming and |
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| is encoded into the media. This |
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| information is used to create a single |
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| rear centre, or two mono rear centres |
|
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| depending on the speaker setup (6.1 |
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|
| or 7.1). |
DTS | Discrete | Similar to Dolby Digital in practice, | |
|
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| though it uses a different technology. |
6.1 | Mostly Discrete | The centre rear channel is a matrix | |
|
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| channel encoded into the left and |
|
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| right surround channels. The |
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| processor reads flags and “unfolds” |
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| the centre channel information; all |
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| other channels are discrete. |
6.1 | Discrete | All 6.1 channels are discrete | |
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|
|
DTS Neo:6 | Matrix | Designed for the playback of film or | |
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| music sources and can derive 5 or 6 |
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| channels with surround and/or rear |
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| speakers |
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