Opinion neede on reduction of Audio Bit-depth of DVD

chewbonkay wrote on 6/27/2002, 9:31 AM
I have a 105 minute wedding video I want to fit on a single DVD-R. Usually I render separate streams and drop an .m2v and a .wav file into MyDVD. (I know most people slam this package, but it came free with my DVD-RW and I have learned to use it successfully for now with things like unlimited chapters and custom buttons).

In this case my .wav file 48kHz 16-bit is eating up 1.16 GB of my 4.3 available. I have tried several different custom video renders (VBR) and even it a rate of AVG 4.5 and Max 7.0, my combined file is still 4.47 GB and won't fit.

What do you think of resaving the .wav file as 8-bit thus freeing up over .5 GB? The audio is typical wedding type stuff so we're not talking cutting edge audio here. Would the audio become noticeably worse?

As always, any information would be great. Thanks much.

(please note - sorry if this posts shows up twice. I posted it about 2 hours ago and it never showed up??)

Comments

jetdv wrote on 6/27/2002, 10:24 AM
To get 105 minutes, you will have to reduce your MPEG2 encoding rate to 4,150,000 which will still allow enough room for the audio. The only other alternative is to upgrade to a DVD authoring program that will convert the audio to AC3. If converted to AC3, the encoding rate could be 5,500,000. Programs that can encode AC3 include DVDit! PE and ReelDVD.
owlsroost wrote on 6/27/2002, 12:55 PM
I don't think the DVD spec allows for PCM audio less than 16bit/48kHz stereo, so I think the AC3 route is the only option to get the audio size down for NTSC DVD.

If you supply other audio formats to MyDVD it converts them all to 16bit/48kHz PCM on the disc anyway as far as I know.

Tony
vonhosen wrote on 6/27/2002, 2:06 PM
I know with Sonic's DVDit you can bring your 48Khz .wav file in as 8 , 16 or 20 bit.
Whether it will be conveted to 16bit for output I don't know. I believe it is as owlsroost suggested it has to be 16bit at least. But you have -RW so give it a go, what's the worst that can happen ?

(The original post is in Videofactory !)
riredale wrote on 6/28/2002, 8:11 PM
What about encoding the audio into the MP2 format? As you can see from the numerous prior discussions, this is a popular thing to do, but it means that you won't get quite as good a compatibility with set-top DVD players as with AC3 or PCM. I also don't know whether your authoring program will accept such a format.

I think the rule of thumb is that you gain (or lose) 6db of noise with each bit added or taken away. By this rule, a 16-bit PCM signal has 96db s/n, and an 8-bit signal just 48db, which is worse than the old cassette decks before DolbyB (I guess I'm dating myself with comments like these...).
pelvis wrote on 6/28/2002, 10:24 PM
16/48 PCM is your best bet.