Getting the best settings with nandub...

[Ham]

Can someone tell me why one setting which works fine for a movie may not work well for others? I have a vcf file that encodes a movie to the exact size I want, but I get a larger file size when I encode a larger movie with the same settings. It seems like the larger the file, the more oversized it gets from my target.

How should I adjust the gauge and the drf settings to fix this? If I change the gauge, do I also have to change drf or are these two things independent from each other? Details please.

Here's my current settings for gauge and DRF:

Gauge: min = 30, max = 80, start = 35

DRF: min = 2, max = 16

Keyframes quality: min = 4, max = 31

BTW, I only use nandub for re-encoding large avi files (800-1000Mb range) to make them smaller so they can be burnt on a 80min CD-R.

Any suggestions to help me hit the targeted file size (700Mb) is appreciated.

[Enchanter]

Different movies will have different bitrate curves and hence you cannot expect they will behave the same way under the same settings. Note also that dark movies generally require less bitrate and hence tend to come out undersized. In your case, were you comparing a movie with a lot of dark scenes to another that happens mostly in bright areas?

You can use the gauge settings to influence the filesize. The lower the gauge values, the smaller the filesize will be. However, try not to bring down the min. gauge too low or you may start experiencing dropped frames. In my experience, the max. gauge will have the largest effect on final filesize.

Just a little note. Using a DRF of min:2 and max:8 should give good results too. This shouldn't have any effect on the filesize, but more on quality.

p.s. You wouldn't happen to be using the same amount of bitrate for the movies, would you?

[Ham]

I'm using the built-in bitrate calculator to calculate the bitrate for each movie.

So should I decrease BOTH the min/max values of the gauge by decrements of 10 till I get the targeted file size? Would changing the gauge values affect the quality of the movie too much besides dropped out frames as you have mentioned?

[Enchanter]

As I said, changing the max gauge will have the most effect on filesize, unless your movie is 99.99% conversation with the characters sitting comfortably on chairs. The min gauge setting is there to prevent the bitrate usage from going too low and resulting in dropped frames. Basically, Lower gauge values = smaller filesize.

As a note, the original DRF setting you used is the commonly used one and one that most calculators (even the built-in one) conforms to. But if you find that it is not accurate, it is time to go with your gut feelings and play around with the gauge settings and/or bitrate amount itself.