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100 Everything You Ever Wanted to Know About DVD<br />
720�480 720�576<br />
704�480 704�576 352�480 352�576<br />
4:3 0.909 1.091 1.818 2.182<br />
16:9 1.212 1.455 2.424 2.909<br />
For the gory details of video resolution and pixel aspect ratios, see Jukka<br />
Aho’s Quick Guide to Digital Video Resolution and Aspect Ratio Conversions<br />
(www.iki.fi./znark/video/conversion).<br />
What Are the Audio Details?<br />
DVD comes in two home-entertainment flavors: DVD-Video and DVD-<br />
Audio. Each supports high-definition multichannel audio, but DVD-Audio<br />
includes higher-quality PCM audio.<br />
Details of DVD-Audio and Super Audio CD (SACD)<br />
Linear Pulse-Code Modulation (LPCM) is mandatory in DVD-Audio discs,<br />
with up to six channels at sample rates of 48/96/192 kHz (also 44.1/88.2/<br />
176.4 kHz) and sample sizes of 16/20/24 bits. This enables a theoretical frequency<br />
response of up to 96 kHz and a dynamic range of up to 144 dB.<br />
Multichannel PCM is downmixable by the player, although at 192 and 176.4<br />
kHz only two channels are available. Sampling rates and sizes can vary for<br />
different channels by using a predefined set of groups. The maximum data<br />
rate is 9.6 Mbps.<br />
The DVD Forum’s Working Group 4 (WG4) decided to include lossless<br />
compression, and on August 5, 1998 approved Meridian’s Meridian Lossless<br />
Packing (MLP) scheme, licensed by Dolby. MLP removes redundancy<br />
from the signal to achieve a compression ratio of about 2:1 while allowing<br />
the PCM signal to be completely recreated by the MLP decoder (required<br />
in all DVD-Audio players). MLP enables playing times of about 74 to 135<br />
minutes of 6-channel 96 kHz/24-bit audio on a single layer (compared to 45<br />
minutes without packing). Two-channel 192-kHz/24-bit playing times are<br />
about 120 to 140 minutes (compared to 67 minutes without packing).<br />
Other audio formats of DVD-Video (Dolby Digital, MPEG audio, and DTS,<br />
described later) are optional on DVD-Audio discs, although Dolby Digital is<br />
required for audio content that has associated video. A subset of DVD-<br />
Video features (no angles and no seamless branching, and so on) is also<br />
allowed. Most DVD-Audio players are “universal” players that play DVD-<br />
Video discs as well.<br />
DVD-Audio includes specialized downmixing features for PCM channels.<br />
Unlike DVD-Video, where the decoder determines how to mix from six chan-
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