CREATING AUDIO-ONLY TITLES FOR DVD-VIDEO

May 1, 2003 12:00 PM, Gary Hall

           
 

As musicians, we usually focus our interests on sound and music, often divorced from any visual program. It seems perfectly natural to us to approach DVD as an audio-only medium, like a CD with capability for higher fidelity, more channels, and very long play time. It's possible to treat DVD in this way, but the provisions of the DVD-Video specification and the feature sets of many authoring tools do not make doing so as simple or obvious as it might be.

In fact, according to the spec for DVD-Video, there is no such thing as an audio program without picture. In DVD-Video, a clip of audio is always accompanied by visual content, which can be either video or a still image.

To create “audio only” DVD-V discs, you have to insert a single still picture (even a simple black image if you wish) along with the audio program. Unfortunately, many lower-cost DVD authoring tools do not support the use of still pictures. If that is the case, then the only option is to make a section of video to fit the length of audio. This presumes you have some means to create and handle video.

Apart from the question of whether your authoring software can support the DVD-Video construct of a single still image along with audio, many lower-priced authoring packages do not support the audio formats that are of interest to musicians. Nearly every program today supports uncompressed (linear) PCM audio, but most “affordable” tools limit resolution to 16 bits and sampling rate to 48 kHz. If you're interested in higher-resolution options, you may have to purchase a more professional package or use a service bureau that has the necessary tools.

Although the least expensive DVD-production tools tend to support stereo audio only, multichannel surround in Dolby AC-3 format is available in most midrange and higher tools. Be sure to check if AC-3 encoding is provided with the authoring software or if it must be purchased separately. As of this writing, only the most expensive versions of “professional” DVD-authoring systems are able to import audio in the DTS format that many audiophiles prefer.

The bottom line is this: if you're interested in creating DVDs that focus on sound rather than picture, take a close look at the feature set of any authoring tool you plan to use. Trying to produce audio-oriented DVD titles with the wrong tool set can be a frustrating experience.

On the other side of things, a few companies are starting to introduce products designed specifically for audio on DVD. Sonic Foundry recently released a 5.1 Surround Plug-In Pack that provides rendering, encoding to AC-3, and transfer to DVD-R in DVD-Video format for surround mixes or stereo mixes produced in Acid Pro 4.0 or Vegas 4.0 (see Fig. A). The resulting discs play in linear fashion, displaying song titles as background images.

Ego Systems is taking a different approach: it is developing the first standalone DVD recorder for audio. The M-Fire 9600 ($1,995), which is still under development, includes 24-bit, 96 kHz stereo A/D converters. An analog or digital audio input is recorded directly to DVD-R in DVD-Video format, with pure black as the visual background.