DVD 5:1 encoding
 

Can anyone clear up a little mystery regarding the "streaming bit-rate" required for 5:1 audio on DVD video?

I recently submitted, as requested, an .AC3 file of a 5:1 soundtrack to a video for DVD authoring. The authoring facility had not specified a "streaming bit-rate" or data rate. When I used the encoding software for the first time (Sonic Foundry's Soft Encode) I discovered several data rates available, but no guidance as to their application. Assuming (wrongly it now seems) that DVD could handle the very best and fastest rate, I encoded at a data rate of 640. The DVD production house phoned me to tell me that the AC3 file could not be imported into their software due to the data rate being "Outside the boundaries". The engineer seemed to know nothing really about this problem, and referred to another member of his staff who informed me that the data rate needed to be 448, but that I'd better supply one at 256 "just in case". Looking at the encoder software I notice that at 256 the audio bandwidth is reduced to 15k. Not exactly what I had in mind. My cliemt has lost a day's work (travel to the post-house - there isn't one that does DVD here in Birmingham as far as I know) so it'd be really good to discover that the files I supplied were not unsuitable. And yes, I'd have thought they'd have their own encoding program too! I did supply the stem files just in case, but they were unable to do anything to these. The client chose the post-house; I have a feeling I need to develop a relationship with one that knows this area a little better.

If anyone out there can clear up this matter I'd be very grateful, since I'm about to produce two more 5:1 soundtracks for DVD authoring.

And what about .DTS files? I thought they were the standard for DVD audio, but apparently the program being used to create the DVD does not support this format. I've read many articles on the aesthetics of 5:1, and some of the technical problems regarding monitoring etc, but found not a lot on issues such as those raised here. I am a composer, not an engineer, and simply need to know what format to provide post-houses with.

Thanks in advance, I'll post this on the other groups.

Simon Scardanelli