It is recommended that you compress your uncompressed AIFF and WAV PCM stereo audio (WAV audio sources should be used with A.Pack) that you get as part of your elementary streams from Mpeg 2 encoders, into simple stereo Dolby Digital (AC3) for use in your DVD projects (Mpeg audio should not be used for NTSC DVDs).

The Main reason to do this is to make more room on your disc for video elements; giving your video a higher encoding bit rate to maintain the quality of the show. A stereo Dolby audio file can be 1/7th the size of the same stereo uncompressed PCM audio file! The audiophiles amongst us might be able to notice some quality difference between the two audio streams after compression, but most won't.

Another reason, and this is a biggie; DVD recordables need as low a bit rate as you can put on them (video and audio combined data rate). The difference between an uncompressed stereo audio stream at 1.57mbps, and a compressed Dolby stereo stream at .224kbps, can be the difference in the DVD-+R playiing reliably in most players.

One of the big misconceptions about Dolby Digital audio streams is they have to be 5.1 surround sound. Not so. Dolby stereo (left, right) is perfectly acceptable.

Here's the settings as seen in DVD Studio Pro's Dolby encoder, A. Pack (The default settings will muffle your audio!). The following settings are good for any Dolby encoder that you may run across, as they're all standardized as far as settings options go.

The Settings

As shown above: under the Audio TAB, choose DVD Video for the Target System. For Audio Coding Mode: its 2/0 (L, R). For Data Rate I recommend 224 kbps for Dolby stereo streams. And set the Dialog Normalization to 31 db (we don't want any Dialog Normalization, normally. Be sure to hit return to make the dialog norm setting stick). And the Bit Stream Mode can be adjusted to reflect your material (usually it's either Complete Main or Music and Effects, depending on the dominance of your sound track's contents).

The Preprocessing Tab is the other setting group we need to be concerned with (shown above). Set the Compression to "None". And make sure everything else is unchecked (none of these features apply to simple stereo sound tracks, and can just cause trouble).

There you go. Of course, making sure your sound tracks are recorded with the proper consistent levels across the whole show (or adjusted in your NLE), and equalized to sound good before encoding to Dolby, will help a lot as well. I like to add just a touch of bass, to help keep the punch in the sound track going to Dolby. Experiment here.