Best way to author 24 gigs AVI w/DVDA/Vegas?

ken c wrote on 10/8/2004, 5:55 AM

I'm authoring a new DVD this weekend.... hope someone can help...?

I have 2 hours of uncompressed AVI footage, about 24 gigs. What's the best way to get this onto a 2-hour DVD with a decent cbr, either with DVDA2, or..

should I compress the avi first from within vegas or other program (if so, w/huffy or techsmith or..? codec) before trying to use DVDA2 to author the vobs? (though not as good since that would compress the footage twice)...

In other words, what's the best way to get my source/edited 24 gigs of 2hrs avi footage onto a regular 4 gig DVD?

From what I remember, unless I compress it pre-DVDA, the bit rate ends up being way too low, or it simply won't compress it all correctly using DVDA's vob compression routines (or likely, I am not using it the best way)... tips?

thanks!

ken

Comments

jetdv wrote on 10/8/2004, 7:42 AM

I have 2 hours of uncompressed AVI footage, about 24 gigs

No, you have 2 hours of COMPRESSED DV-AVI footage. DV-AVI file are not uncompressed.

What's the best way to get this onto a 2-hour DVD with a decent cbr

The EASIEST way is to simply load the AVI file into DVDA and let it render to MPEG2 and AC-3 for you. There's a "fit to disk" option which will allow it to pick the proper bitrate.

Alternately, you can render the MPEG2 and AC3 in Vegas. If you do this, you have more control but you MUST click on the custom button and set the appropriate bitrate.

ken c wrote on 10/8/2004, 7:44 AM

Hi thanks ... right, the problem I've had in the past is that it won't fit all to disk, or the bitrate is so low it produces low-quality vobs, so, I wanted to know if it would be better to say re-render into avi with huffy or techsmith codec (or even to mpgs) Before having DVDA render the final vobs ... any thoughts on best workflow for that?

appreciate it..

ken

johnmeyer wrote on 10/8/2004, 8:07 AM

As jetdv says, the easiest is just to put the AVI files into DVDA and let it render using fit to disk. That will give you the highest bitrate that will "just" fit the single DVD. Alternatively, you can render in Vegas and use a bitrate calculator to get the approximate bitrate you need. Here's a link to one such calculator:

Bitrate Calculator

You can also use this formula to get a close approximation:

Average bitrate (in megabits per second) = 590 divided by project minutes

This calculation assumes that you are encoding your audio using the AC-3 encoder, and using the default “Stereo DVD” template, which encodes at 192 kbps.

So, if your Vegas project is 80 minutes long, then you should encode at no more than 590/80 = 7.38 megabits per second. Since Vegas expects you to input bits per second, not kilobits per second, you would enter 7,380,000 for the average bitrate in this example.

For exactly a two-hour project, you would use an encoding rate of about 4,800,000.

The advantage of encoding in Vegas when doing a long project that requires a low bitrate is that Vegas has a 2-pass option (which you will find when you click on Custom in the Render As dialog) which can improve quality for low-bitrate encodes.

rs170a wrote on 10/8/2004, 11:03 AM

John is right about the 4,800,000 bit rate.
I fed 2 hr. into the bitrate calc I use (Mark's DVD bitrate calc version 1.0.6 - sure wish I could find it on the net again for others) and a 2 hr. DVD gave me these numbers:
CBR - 4,7767000
VBR - Min. - 2,864,000
Avg. - 4,776,000
Max. - 8,352,000
BTW, I did a 2 hr. encode earler this year (school play) and it looked great. Mind you, it was shot on a (2/3") 3-chip JVC 550 so the quality was excellent to start with.

Mike

ken c wrote on 10/8/2004, 5:03 PM

Thanks very much - that's exactly what I was looking for -- I wasn't aware that Vegas does a 2-pass vs DVDA single-pass encode, that can make a significant difference ... and every edge counts... thx all!

I'll encode out using Vegas, and not rely on DVDA for the primary compression, but rather just for the vob authoring ...

Thx John for the link ... that's the site who's tutorials I used to learn about video authoring from a long time ago (pre-Vegas)... great to see how far things have come with the help of vegas/DVDA... that bitrate calculator will be a big help .. as I have dozens of chunks of avis to string together + encode for the final DVD...
appreciate it.

ken