Bitrate

[Mike Kujbida]

Steve, here’s what John Rofrano had to say about bitrates in the Rendering 2 hour video to DVD….understanding bitrates thread.
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The Average bitrate is what’s important to file size. It determines what the overall average for the entire file will be. The Maximum bitrate says that you can go up to that if you need it but you must steal from other frames later to maintain the average. The Minimum bitrate is just a floor to not go below.

When you start dealing with lower bitrates you can sometimes get better quality by using the 2-pass option. this takes twice as long to render because it makes one pass to determine the bitrate it needs for each frame, then it plans where it wants to use the bits that it has available based on the need and makes a 2nd pass to do execute the plan and do the actual encoding. This way you get maximum utilization from your “bit budget”.
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I use a bitrate calculator for anything I do that’s over 70 min. in length for the simple reason that I find the stock templates far too lenient and I want to get the maximum quality possible.
For example, the DVD Architect NTSC video stream template in Vegas uses a VBR setting of 9,500,000 / 6,000,000 / 192,000.
By way of comparison, Mark’s Bitrate Calculator gives me a VBR of 7,904,000 / 6,320,000 / 3,792,000.
BTW, if my numbers are different than yours, it’s because I bumped my safety margin up to 5% from whatever the default was (1%?).
As I’ve said earlier (and it’s been repeated by a number of users a lot smarter than I am abouth this), never exceed a Maximum bitrate of 8,000,000 as this may cause problems with cheap media and/or the DVD player.
With Mark’s calculator, the Average bitrate as well as the Minimum are higher which translates to a better quality picture.

Sorry for the long response but hopefully this explains why I do what I do.

[Steven Talley]

The idea is to render as high of a bit rate as will fit on the target media. A bit rate calc helps in that regard. Audio has to be factored in with it also.

[Mike Kujbida]

Thanks for the reminder Steven.
Audio in the Settings screen in Mark’s Calc is set to 192 Kb/s – Dolby 1.0 (Vegas AC-3 default – can be changed if desired).
Setting it on this 2nd screen will automatically load it as soon as you select a disc type on the main screen.

[Steve Edwards]

I use Vegas 8 Pro, and usually render there to mpeg2 (using the NTSC DVD template, not the Architect stream setting). Then I import those videos into Adobe Encore, and author the video there. So, am I doing this the correct way, and if I go custom template, do I use a CBR or VBR, and if I use VBR, am I better to choose the average setting?

[Steve Edwards]

So for the AC-3 setting, it is 192kbs (Dolby 1)?

[Mike Kujbida]

Then I import those videos into Adobe Encore, and author the video there. So, am I doing this the correct way…

I’ve never used Encore so I don’t feel qualified to answer this question as I may be completely wrong.

[Mike Kujbida]

192 Kbps, 48,000 Hz, Stereo is the default AC-3 setting for Vegas.
Adobe may want something lower or higher but you’d have to check to be sure.
I know of some Vegas users who will kick it up (for whatever reason) to 384k.

[Luc Enders]

Never ever use CBR if your average bitrate is below 8Mb/s unless max quality is not most important. If you don’t choose VBR multi-pass you will lose some quality. Exception potentially is a slideshow (except for transitions) but extra cost of MPEG2 SD VBR is really cheap nowadays.

The average bitrate obviously decides the file size. Don’t forget as mentioned that you’ll have to add little bit of overhead for DVD menus. Look for a calculator that adds video + audio (I assume the bitrate calc referenced above allows you to enter AC3 bitrates).

For 1:30 video and 192Kbs AC3 audio you end up at around 6Mb/s as mentioned (max I’d set at 8Mb/s and min depends but typically 3-4Mb/s for most videos). I also would not exceed 8Mb/s for video. I’ve seen cases where it caused stutter in some DVD players (with self-burned DVD’s).

For best DVD compliance use AC3 audio always with 48KHz and either 192Kbs or 224Kbs works (officially bitrates between 32-1536 are supported).

The 384k bitrate is commonly used for 5.1 channels (and often commercial DVD’s are 448Kb for 6 channels).