Cool! Thanks

Just an update on this - it worked and looks great. I was able to fit 2 hours onto a dvd-5 easily, and the quality is excellent. I think the max I used was 6000, min was 4000 - I'm not at home so I don't quite remember. The only thing is, it took a loooong time, 6.5 hours to render this on a P4 2.4 gHz. Network rendering might help with this, I'll try that this weekend.

Now, I have a question on 2-Pass VBR in general. Is there any reason to use this on shorter projects? If I have a 45 min project, will I get better quality results using 2-pass, or will I just get a smaller file?

The way I understand 2-pass VBR is that by using it you get better quality over 1-pass VBR. VBR is Variable Bit Rate, so when encoding the movie Vegas will adjust the bitrate to the amount of movement in the scenes. By doing 2-passes Vegas will make better adjustments in the encoding. 2-pass VBR will always take longer to encode becasue it goes through the project twice.

The file size is determined by the bitrate settings you use. Lower average bitrate means smaller file/lower quality. Higher avg bitrate means larger file/higher quality.

Right, got all that.

It stands to reason that using VBR with a max of 6000 will be no better quality than using fixed at 6000, correct?

It will definately not be better quality. It may be the same quality, but more than likely it will be a bit worse. Probably not enough to be noticable though. However, VBR in most cases will create a smaller file size depending on what you have set for max, min, and avg bitrates. Using 2-pass is the key to having small file sizes and good quality.

Just to be clear, CBR and VBR produce the same file size. If you set CBR for 6,000 and VBR for 6,000 Average, you get the same file size.

Single-pass VBR only looks a few frames ahead and behind to decide how far above the average rate it can go for scenes with fast motion (which requires higher bitrate to look good) and how far below the average for slow motion scenes. The two-pass VBR looks at every frame from every scene and can therefore know, for instance, that there is a long stretch of almost no motion in one part of the video that can be encoded at extremely low rate, and all those "unused" bits can therefore be available for the faster scenes. Thus, 2-pass gives you better quality, while still using the exact same number of bits overall.

And if you encode at a very high bit rate like, 7000 or 8500 average, a single pass should look about as good as two pass. So if you have a short project (about 55 minutes or less) you can save time encoding by then choosing a single pass VBR with a very high bit rate.

Steve,

Excellent, and very important point. It is definitely a waste of time to use 2-pass until you get down to some pretty low average bitrates. I don't have a rule of thumb that I can swear by, but for me, I usually don't bother until the average bitrate is well below 6,000,000 bps. Certainly, by the time you get below 5,000,000 bps average, you should be using 2-pass.