Correct Bitrate settings in Vegas for DVD Architect

[Don Bloom]

if you are using the readings from DVDA to get your final readings (IE the red and yellow bars in the lower right dorner with the size in gb of the project) DON’T!
It is a gross overestimation of the actual size of the project and is anything but accurate. Why? No one really knows but it’s been like that for as long as I can remember.
If the BR calculator says to use a certain BR for VRB then thats what to use (remember to figure in the audio track as well-be it PCM or DVDAs preferred AC3) If you think it’s too big then check out the file size in the explorer. That’ll be 100% accurate.
Don

[Mike Kujbida]

Rich, my solution was to go into the Settings and increase the “Safety Margin” to 5% (default is 1%, right?).
Based on past renders being well under the limit, this can probably be dropped 1% or 2% but I haven’t bothered doing it yet.

[Rich Kutnick]

1) DVDA would not let me proceed any further unless the file that was chosen either was smaller or I allowed DVDA to re-render it.

2) Coincidentally (e.g., on purpose)I DID check in Explorer and the file WAS 4.82G!

3) I also DID account for the AC-3 audio. Since this was a Super 8 film-to-tape transfer, 99% of the audio track was bare, save for about 3 minutes in the middle of the capture that did include sound from the mag stripe. Other than that, NADA audio! In the bitrate calculator, though, I accounted for the full 1 hr:58 min of AC-3 audio. As you know, the audio is less than one MB for something like this, so the bulk of the problem lies within the video compression.

Rich Kutnick
VIDEO IMPRESSIONS

[Rich Kutnick]

So, Mike, 5% HAS worked for you successfully in the past without error? If so, I will try this on the next set.

Rich Kutnick
VIDEO IMPRESSIONS

[Mike Kujbida]

5% is probably a very conservative setting.
I’m doing renders on a 2 hr. project right now at 1%, 3% and 5%.
When they’re done, I’ll report my size findings.

[Don Bloom]

Rich,
1 hr and 58 minutes for VBR with AC3 audio by my calculations should be around HIGH:8,000,000 AVERAGE: 4,826,000 and LOW: 2,000,000.
What rates did you use? Curiosity has me now 😉
Don

[George Wing]

[Rich Kutnick] “As you know, the audio is less than one MB for something like this, so the bulk of the problem lies within the video compression.”

What does that mean — the audio for almost 2 hours will be alot larger than one MB?

Also, I noticed in Vegas 7 that for VBR, it doesn’t really encode at the AVG bitrate. You have to use 2-pass to get it closer to the AVG bitrate (for predicting final size of render).

Regards,
George

[Rich Kutnick]

OK, my friends, here are answers to YOUR questions:

Don, for a 1 hour, 58 minute video (with only 3 minutes of audio, even though I encoded a complete AC-3 audio track) for an SS/SL DVD with no menus at 1% safety margin, the bitrate calculator shows Minimum 2984, Avg 4984, Max 8720. I actually used 3088, 4900 and 8500. While high on the low end (which it will never get this low), I was a bit conservative on the middle and high figures.

George, my bad! I meant so say 1 GB! Actually the AC-3 audio file compressed to 166.3 megs, FYI. I am curious, though, if I need to use 2-pass VBR to get closer to the AVG bitrate calculated, for I have seen my similar encodes actually are at around the Max bitrate, which could cause these excess file sizes, no?

Mike, please DO let us know what you find out with your three tests at different safety margins.

Perhaps we can come up with the best combination of bitrates (also taking into account safety margins) to use, but don’t you all agree that the bitrate calculator appears to be way off if my file sizes so exceeded 4.7GB? Perhaps I just should stick to 6Mbs CBR for these film transfers and 2-Pass VBR for videos that I have shot (if the latter will compress at more accurate rates based upon the bitrate calculator)?

Any more suggestions would be helpful based upon YOUR actual experiences (since I still am relatively new at calculating bitrates for DVDs and rendering as such), and I await Mike’s results with th hope that he stumbles upon something, too!

Rich Kutnick
VIDEO IMPRESSIONS

[Mike Kujbida]

Sorry for the delay folks but, even on my quad core, a 2 hr. program still takes 2 hr. to render 🙂
Add to that the fact that I was installing trim in our newly painted bedrooms all day so I didn’t have a lot of time to “play”.

Here’s the details.

Program length – 2 hr. 8 min.
Render format:
AC-3 audio: (192 Kbps, 48,000 Hz, Stereo)
MPEG-2 video: (4:3) customized DVD Architect NTSC video stream.

All renders were single-pass VBR.

The bitrate calculator used was Mark’s DVD Bitrate Calculator version 1.06 with the Safety Margin at 1%, 3% and 5%.
Fixed menus was set to 1.
1 kilobit = 1024 bits was selected.

All render numbers were rounded down (for example, 2,680,000 becomes 2,600,000).

Here are the VBR settings (Max, Avg, Min) and resulting file sizes (according to the “Detailed View” in My Computer – more on this in a moment):

AC-3: 179,063 KB

MPEG-2 (1%): 4,195,478 KB
VBR:
7,800,000
4,400,000
2,600,000

MPEG-2 (3%): 4,101,242 KB
VBR:
7,600,000
4,300,000
2,600,000

MPEG-2 (5%): 4,006,802 KB
VBR:
7,500,000
4,200,000
2,500,000

According to these numbers, a 1% safety margin would put it over the allowable 4.3 GB limit but you think you’d be OK with the 3% and 5% margins.

However, here’s where my discrepancy comes in.
When you right-click on the files and select “Properties”, you get 2 different set of numbers (“Size” and “Size on disk” as shown here:

AC-3:
Size: 174 MB (183,360,000 bytes)
Size on disk: 174 MB (183,361,536 bytes)

MPEG-2 (1%):
Size: 4.00 GB (4,296,169,472 bytes)
Size on disk: 4.00 GB (4,296,171,520 bytes)

MPEG-2 (3%):
Size: 4.08 GB (4,383,031,808 bytes)
Size on disk: 4.08 GB (4,383,035,392 bytes)

MPEG-2 (5%):
Size: 3.82 GB (4,102,965,248 bytes)
Size on disk: 3.82 GB (4,102,967,296 bytes)

And, so you don’t have to do the math, here they are combined (what you need to figure out if it’s OK for DVD Architect):

Combined AC-3 + MPEG-2 (1%):
Size: 4.17 GB (4,479,529,472 bytes)
Size on disk: 4.17 GB (4,479,533,056 bytes)

Combined AC-3 + MPEG-2 (3%):
Size: 4.17 GB (4,479,529,472 bytes)
Size on disk: 4.17 GB (4,479,533,056 bytes)

Combined AC-3 + MPEG-2 (5%):
Size: 3.99 GB (4,286,325,248 bytes)
Size on disk: 3.99 GB (4,286,328,832 bytes)

As you can see, only the 5% Safety margin would be OK for DVD Architect.

My question for the computer gurus amongst you is “can we trust the first set of numbers or do we use the last set?”
Call me anal but I always use the latter set of numbers (right-click – Properties) as they’re the largest.
Unless I completely mess up my authoring procedure (it’s been known to happen!!) DVD Architect never tells me it has to re-render anything.

I hope this helps some folks and promotes further discussions on this issue.

[Mike Kujbida]

I forgot to add that, no matter what the bitrate calculator says in CBR or VBR mode, I never go over 8,000,000 for the Max. setting.
From various posts here and elsewhere, this is acceptable for a replicated DVD but not a burned one (what we all do) as exceeding this limit may lead to player problems.
It’s better to be safe than replacing an irate client’s DVD(s) 🙂