mpeg encoding madness....

tbobpage wrote on 1/12/2004, 5:50 AM
I have a 24 gig AVI I'm trying to encode to DVDA. It runs 1:48 realtime, but when I render it (with DVDA NTCS template, best quality) it comes back 5 gigs (too big for one DVD). I set the quality back to "good" and then re-render and it 5.06 gigs (go figure), then I cut three minutes from the video and it comes back over 5 gigs still (acutally, bigger than when it was 1:48), then I crank back the variable bit rate from 8,000,000 to 7,000,000 and it comes out 5.14 gigs. Can someone enlighten me as to what the heck is going on here? How can I figure out how to adjust the settings on this to get it under 4.7 gigs (acutally, less so I can include the audio stream). I only have so many chunks of 2.5 hours to let this thing chug through the rendering process.....

thanks all,

todd

Comments

PeterWright wrote on 1/12/2004, 6:01 AM
If you put the avi into DVDA you can use the optimize feature to reduce the bitrate until it all fits, then let DVDA render it.
tbobpage wrote on 1/12/2004, 6:11 AM
Great! But will it retain the markers I put into the project for the chapter points or will I need to redo those?

thanks for the help.....

But do you have any ideas as to why the encoding does what it does out of vegas -- I don't understand how I can make a file smaller but end up with a longer rendered file size....
PeterWright wrote on 1/12/2004, 7:22 AM
Yes - if the markers are there in the avi, they will carry through into the MPEG2 when DVDA encodes this.

And No - I don't know why you got those strange results either!
tbobpage wrote on 1/12/2004, 12:54 PM
Peter,

Thanks for sticking with me on this. Let me elaborate a bit. I took the original edited video and rendered it to an AVI, then added markers, then was going to render it to MPEG-2 (with the DVDA template). SO, I see if I take that AVI and load it into DVDA it will optimize for me, but the only way I will keep the markers would be to re-render the avi as an avi with the markers, right? EG, theres no way to save it as the AVI itself but with just the markers added? Actually, that probably wouldn't take long to render anyways since there's no new formatting, eh? Maybe it would just be easier to just put the markers in again in DVDA.

todd

todd
Spot|DSE wrote on 1/12/2004, 1:14 PM
You can either render as avi in Vegas, you could just as easily take the finished avi that doesn't have markers, drop it in as a new track to the original project that contains the markers/unrendered media, Render with markers and it would be exceptionally fast. Drop that new avi into DVDA, and you'll have the existing markers you started out with.
DVDA will figure it all out for you, and render the audio as AC3 as well, saving space that you might have not originally been able to take into consideration.
tbobpage wrote on 1/12/2004, 1:26 PM
PERFECT!

Thanks for your help.....

A funny aside -- I had just read your post about the new book project, then went over to amazon to check out your other book, and then back here and pow, look who's replying!

Anyhow, thanks for your help!

todd
johnmeyer wrote on 1/12/2004, 9:55 PM
This is a tremendous shortcoming in the Vegas->DVDA workflow. The "solution" is to use a bitrate calculator. Start by trying this one:

Bitrate Calculator

Unless you are planning to create an orgy of menus, you can just use the defaults. Then, take the "Calculated Bitrate" and use that to encode your video, in Vegas, using MPEG2 and the DVD Architect NTSC (or PAL) template. When that render is finished, render your audio using AC3 and the stereo template. Put he resulting files into DVDA and away you go.

In response to your initial question, the "Good" or "Best" settings make no difference whatsoever in the size of the project. Only bitrate (video or audio) settings will change the size of the files. If you use 1/2 the bitrate, your file will be 1/2 the size.
tbobpage wrote on 1/13/2004, 6:10 AM
John,

Thanks also for your help. That calculator will come in very handy. I have been finding out there are several progs out there that offer more assistance automatically in this area but cost much less then vegas.... maybe in the next version....

SO, my question back is, what then is changed when you change the quality from good to best if the project doesn't change in size at all?

thanks again,

todd
PeterMac wrote on 1/13/2004, 8:12 AM
Here's something you might want to try.

Author and create your DVD without regard to the MPEG2 settings. Use the defaults. DVDA (or whatever you're using) will protest that the files you are about to output to the hard drive will be too big for a DVD5 blank. Ignore it and go ahead.

Now, get yourself a transcoder (compressed domain transcoder). They cost a very small sum, but one of the best 'DVD Shrink' is free. Pass your oversize files through Shrink and you will get within a few Mb of the target size. If you set its 'Deep Analysis' mode, it is unlikely that you'll see any quality loss either. The total [unattended] time to do this is about an hour.

Good luck!

-Pete
johnmeyer wrote on 1/13/2004, 10:54 AM
what then is changed when you change the quality from good to best if the project doesn't change in size at all?

"Best," "Good," etc. change the algorithm used for the encoding. Some algorithms use different math than others, and some look at more frames before deciding what to do, etc.

I recommend that you read the Sony MPEG Encoding Guide, found here:

MPEG Encoding Guide

In Vegas, if you click on "Custom" while in the "Render As" dialog, the "Project" tab shows the "Vendeo Rendering Quality" listbox. If you click on the "?" in the upper right corner of the dialog, and then click on this listbox, you'll get a help menu that describes the difference between the settings.
MUTTLEY wrote on 2/6/2004, 2:25 AM
Realize this is an old topic but:

Spot, you said " DVDA will figure it all out for you, and render the audio as AC3 as well ". Why isn't it listed or don't I see an option for AC3, I'm confused.

And another thing, though I ticked " Save Project Markers ... " when rendering as DVDA they don't show up in Architect ... ?

- Ray

www.undergroundplanet.com