Wrong sample rate for DVD project

musicvid10 wrote on 8/10/2008, 9:15 AM
I started with 4 audio tracks that were recorded at 48K 16 bit on two genlocked and TC synced XLH1's.
I did some general preprocessing on the audio in Sound Forge (mostly stereo conversion, EQ and spot fixes) but accidentally saved it at 44.1K PCM (the default in SF).
I'm quite satisfied with the audio, and don't want to go back and do all the preprocess work again, but I wonder how to render the final audio (which will be AC-3 5.1).

My Vegas project matches the video and audio (44.1K) properties. Do I:
1) Render it out to AC-3 at 48K, or at 44.1K?
2) Or do I go back to SF and render all the processed files back to 48K and then bring them into Vegas?

Conventional logic tells me to minimize my losses and leave it all at 44.1K when rendering; however, I wonder if I am creating problems for some DVD players by having a nonstandard bitrate in the final 5.1 audio.

Anyone done some tests to see if converting 48->44->48 creates any audible differences?

Comments

owlsroost wrote on 8/10/2008, 3:34 PM
The DVD-Video standard (as far as I know) doesn't allow 44.1 kHz audio - it has to be 48 kHz AC3/DTS or 48/96 kHz (LPCM stereo only).

The upshot of this is that the DVD authoring tools should either refuse the 44.1 kHz files or re-encode/re-sample them to 48 kHz anyway, so you don't really have a choice......

Tony
johnmeyer wrote on 8/10/2008, 5:12 PM
DVD AC-3 is 48kHz only, about 95% certain.
musicvid10 wrote on 8/10/2008, 7:24 PM
Well, the AC-3 at 48kHz sounds terrific, so I guess I won't sweat the small stuff this time.
Next time around I'll be sure and check to see that the rendering template in Sound Forge is the same as the source.
Some quick checking verifies that 48kHz is the Dolby Digital standard, with some variations in the DVD spec for different audio formats.
http://en.wikipedia.org/wiki/DVD-Video#Audio_data