BitRate Calculator Variable Question

kentwolf wrote on 7/13/2003, 9:02 AM
I am going to try to start pre-rendering video files right out of Vegas so as to speed up my DVD Architect project creation. Nothing is more frustrating than waiting 4 to 7 hours for DVD-A to render a project with AVI file input only to see a typo on a DVD menu…

I found a Java app bit rate calculator on DVDhelp.com. It looks pretty good, but I am curious as to the sound bit rate to enter.

Seeing I am not interested in 5.1 sound, I would just want to use Stereo sound… or so I think.

According to the DVD-A manual:

AC3 Audio:

Number of channels: stereo or 5.1 surround
Bit rate: 64 kbps to 448 kbps inclusive

Question:

1.) Does this mean that if I desired stereo sound, this would be rendered from Vegas at 64 kbps and that if I desired 5.1 surround sound, that would be rendered from Vegas at 448 kbps?

2.) What are the ramifications of the “inclusive” term here?

(Number of channels is also a variable for this particular bit rate calculator.)

3.) If I did decide to go with 5.1 sound, would this be a single (1) channel of 5.1 sound? Six (6) channels?

4.) Would stereo sound be two (2) channels?

I have always let DVD-A do these calculations automatically, but now I am going to try to start doing them myself.

Thank you very much for any help you can offer.

Comments

riredale wrote on 7/13/2003, 7:42 PM
Dolby Digital can use a variable number of separate audio channels and a variety of bitrates. The most common is 2-channel (stereo) running at 192Kb/sec. You can use a lower or higher bitrate for 2-channel, but a higher bitrate doesn't appear to gain anything in terms of fidelity, and a lower rate will cut your high frequency response.

You don't need a calculator to figure out your bitrate. As mentioned before on this board, just divide 600 by the number of minutes in your video. The resulting number is your average bitrate (including audio) you need to have in order to fit everything into a DVD-5 blank.

For example, if you have 90 minutes of video, your total bitrate is 600/90=6.7Mb/sec. Subtract .2Mb/sec for your Dolby audio, and you have 6.5Mb/sec as your target average video bitrate. I would set my VBR minimum at 0, my maximum at 9, and my average at 6.5. Done.