Rather than referring to 5.1, 4.1 or whatever channels, I prefer to refer to 3/2.1, where 3 is the number of front channels, 2 is the number of discrete surround channels, and.
The Dolby Digital 6.1 system (technically, it's THX 6.1) does not have a discrete centre rear channel, but has the centre channel information encoded into the regular left and right surround channels in the same way as the Dolby Pro Logic centre channel is encoded into the front left and right channels.
The DTS 6.1 ES Discrete format is likely to be the highest number of channels used. It does, however, have an upper limit of 5.1 discrete channels, while DTS is apparently unlimited and MPEG can support up to 7.1. As with DTS and MPEG (and Meridian Lossless Packing which is used on DVD Audio), Dolby Digital can support as few as 1.0 channels. Dolby Digital is a compression technique, just as DTS and MPEG. Many people think that Dolby Digital necessarily means 5.1 channels, but that is not so. A few titles, particularly from Roadshow which was early on the Australian DVD scene, appeared using MPEG, but the lack of equipment supporting MPEG decoding, and the space consumed by PCM (stereo 48kHz PCM uses the same amount of space as full rate DTS) soon made Dolby Digital the de facto standard. However the third alternative is allowable outside the United States: MPEG audio. PCM – Pulse Code Modulation – is the uncompressed digital standard used on CDs, although when it is used on DVDs it tends to be at the 48kHz sampling rate rather than CD's 44.1kHz, and may be as much as 96kHz with 24 bits of resolution. If you read US publications, they will talk about there being only two: Dolby Digital and linear PCM. That's because Dolby Digital is one of the three audio systems of which at least one is required by the DVD licensing agreements. This version: 28 June 2003, previously published in DVD Nowĭolby Digital sound tracks almost always appear on DVDs. Hi Fi Writer - Dolby Digital, from 1.0 to 5.1 Home Page |ĭolby Digital 5.1, it ain't necessarily so
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