Argh! From what I've read, jetdv is a smart guy, but....

Don't let anyone tell you what settings you should use to fit this much video/audio in that much space. The variables are too great for anyone to make such a definitive statement. Instead, you need to take several things into account.

What is the length of your video? How was it encoded? How was the audio encoded? If you used DD, what bit rate did you use, 448, 384, 192?

One of the better tools to help you decide how much to squeeze your video to fit in a given space is the Bit-Rate Calc offered on DVDRHELP.COM. Here's the URL:

http://www.dvdrhelp.com/calc.htm

This downloadable tool will save you tons of wasted effort trying to guess what bit rate to use. It takes into account the length of your video and the type of audio encoding along with menu data and everything else to give you a really good idea what to do.

I get encoded video from a city government for whom I publish to DVD. They encode with an Optibase card (the cheapest one they offer) at 3 Mbps. They encode in real-time from a video switcher while the recording is made and since it's almost totally talking heads it's not too bad. Because of their bit rate I can easily fit 2 1/2 hours on a single DVD-R, including about a dozen still motion menu graphics. This even includes a copyright warning and a logo video from Dolby Labs.

You see, there is no hard and fast rule and even the top experts in the field will tell you that.

Good luck.

Don't let anyone tell you what settings you should use to fit this much video/audio in that much space. The variables are too great for anyone to make such a definitive statement. Instead, you need to take several things into account.


You are correct. My numbers were based on a formula using AC-3 encoding at 192 (standard) set to fill a DVD with a very small amount of overhead. However, these numbers WILL be in the ballpark. If you want to be extra safe, drop 100,000 or 200,000. This will leave more room for menus. However, my numbers were derived from a standard formula:

(36096 - (((# Minutes * 60) * 192) / 1024)) / (# Minutes * 60)

I now see that there is an option in DVDA to "Optimize DVD" and there you cna use a slider to change the bitrate and "fit" your video.
I'll also check out that calculator.
thanks all

Some good input on this thread....

One quick question---- Whatever bitrate you use, should you use the variable (min and max) or constant?

If "variable" is the best option, what would you set the minimum value to? A few 1Mbps less than the max?

Thanks....

I use VBR with max of 8,000,000 and min of 2,000,000

Look at it this way... the standard for VCD is just over 1 Mbps and for VCD it's just over 2. The great advantage of DVD is that you can selectively set the bit stream up to the maximum allowed of 9.8 Mbps.

Early movie DVD's were encoded at Constant Bit Rate (CBR) at around 4 Mbps. Many people though this was the setting to use, however as most know, a film transfer is different and a letterboxed encoded stream is different still (very little encoding required for black bars). Film also presents media differences that affect the encoding process, such as contrast, images per seconds, etc.

The advantage of CBR is that every frame has equal bandwidth available. There is almost no need for multiple passes for a good result because every frame is encoded fully. The downside is that bi-directional and predictive frames are encoded at the same rate as intra-pictures even though they are much smaller images. This means much larger files. Again, in the early days of DVD, dual-layer technology till had a reject rate of over 80% so most titles were release as dual-sided single layer with minimal menus and a single audio track.

Another consideration is the quantization matrices used by the encoder, but that's a really lengthy discussion.

What I do...

Leave the settings alone. USE THE DEFAULTS. Render to a reburnable disc, if it fits. If not, then let DVD-A recompress. Try it on your set top player. Look OK? Finished. If not, ask yourself a tough queston. Does it really have to be 1.5 hours long? Probably not. So if you're only over 10 minutes or so, and don't want to let DVD-A compress it a bit, back to the editing process. Repeat the steps. Make the SOURCE file a bit smaller.

Using a constant bitrate is generally a bad idea. The parts of the movie that could benefit from a higher bitrate which you get automatically using VBR are cheated. Worse the parts that don't need such a high bitrate are just wasting space on the DVD. Talking heads or similar none action scenes don't need a 6,000,000 bitrate!

Like with other things, its a trial and error process. If you can get through the whole process in one pass, pat yourself on the back. If not, so what? The only time you should want to really drop the bitrate is when you're starting with a less than high grade source file. The reverse is also true. You're only fooling yourself if you take an average quality source file and think pumping up the biterate when you make you DVD will somehow make it look "better" because you used a higher bitrate.

If you're making a "big" project, one more than a few minutes beyond a hour, do yourself a favor. Render to AVI using the DVD-A template provided, then render the audio seperately and import that. In the long run you'll save time and still get good quality letting the software decide if and how to compress, because it will use the variable bitrate and that almost always gives better results because the parts of the source file that needs higher bitrates gets it and the parts that don't, won't.

Also... avoid the tempatation to fiddle with the various encoder settings UNLESS you know WHY one or more should be changed... don't. They are what they are for a reason. I'll assume they are what they are for a reason, likely lots of real world testing by the software engineers that developed it. DUH! So unless you think you know better (snicker) you again are only kidding yourself.