Hotwired: Listening nirvana

Having previously sought to explain why there are so many different types of blank DVD discs, variously appended +R/-R/RW/RAM etc, to choose from, it's time to consider yet another significant DVD variable - the DVD-A.

DVD-Audio is a separate entity from the DVD-video format we commonly think of and refer to simply as DVD.

Like SACD (Super Audio CD, which came under this column's spotlight a fortnight ago), DVD-A is a high-definition music format, delivering better stereo sound than standard CDs and, more to the point, much better multi-channel sound than ordinary DVDs.

At the risk of repetition, from an audiophile viewpoint CDs have two main problems. One is that they have a dynamic range restricted to only 96dB and the second is that high-frequency response is limited to 22kHz.

Sure, there is no scientific proof we can hear above that level, anyway, but the argument is that the absence of higher frequencies negatively affects the listening experience. Music enthusiasts wanted a better audio format and it seems very much in the major record companies' interests to encourage as many alternative format purchases as possible. Would you like your Springsteen served on vinyl, cassette, CD, MD, DVD, SACD, DVD-A, Dual Disc or etc, sir?

The first DVD-A players weren't seen until 2000 and, with the added confusion brought by its competitor SACD, the format remains little understood. Some key points, then. All DVD-A players can play normal DVD and CD discs. DVD-A discs can also play on any DVD player showing the appropriate logo, but probably not on your machine if you were keen enough to buy before 2000. They most likely won't, however, play on a CD player - surely the greatest handicap to the format's growth.

Most DVD-A discs contain both stereo and surround-sound versions of the music. They do not contain video, though they can include a little bit. They can and do contain still images linked to tracks, as well as lyrics, liner notes and other information including navigation instructions requiring, obviously enough, connection to a TV screen. They do sound convincingly better than either CD or DVD-Video in stereo or surround sound. There are only a few thousand titles available on DVD-A, like SACD mostly orchestral or re-releases, and they cost $5 to $10 more than CDs.

Stereo recorded onto a CD is standardised at 16-bit chunks of information sampled at a frequency of 44,100 times a second. This is typically written as 16-bit/44.1kHz. DVD-A discs, in comparison, have the ability to hold stereo info recorded at up to 24-bit/192 kHz. You can see that there is significantly more musical information being captured.

To fit on ordinary DVD discs, all multi-channel audio has to be compressed, and that compression noticeably affects the audio quality. For high-definition DVD-A, the multi-channel audio still requires compression, but the algorithm used is MLP, standing for Meridian Lossless Packing - emphasis on loss-less.

With a multi-channel (surround sound) recording, DVD-A discs can (disconcertingly) have you feeling you are in the middle of the orchestra or studio, which can be magnificent. Remember that you will need to have quality multi-channel cabling from your DVD-A player to the receiver and some decent speakers to achieve such listening nirvana.