vHelp Bitrate Calculator not giving the right bitrate.

[gadgetguy]

I've always used the vHelp bitrate calculator to determine the right bitrate to encode my videos at, and it has always worked fine using the default settings, but with my current project it's been recommending a bitrate that's too high and my resulting videos don't fit. The project that I'm working on is to back up an entire series that I have on VHS, 2 episodes per disk. The major difference in this current project is that I want to use the intro (common to all episodes) as the menu background and it's a 43 second clip. I normally only use 10 - 15 second clips for menu background, so I'm sure this is what is causing the problem.
I know I can make adjustments by either customizing the DVD size or adjusting the ISO value, but I don't understand how to determine what to change them to. If I look at the final authored menu structure (which is too big to fit on a single layer DVD), the non-movie bits (IFOs, BUPs, and menu VOB) add up to about 42MB, which is nowhere near what is reserved in the calculator for DVD Overhead (92MB) + the ISO default (25MB).

What am I missing in my calculations?
I'm not real sure what the ISO value is for. Is it to account for the system file structure?

[Baldrick]

ISO is for menus and other data files. You have to calculate the size for motion menus yourself....using a bitrate calculator ...

[jman98]

Why don't you just play it safe by using a value slightly lower than the bitrate calculator recommends? Maybe you don't understand, but bitrate calculators work on the principle that you are going to use 100% of the disc you are writing to and that NOTHING in the encode causes you to overshoot the target. Good luck with that if you are doing VBR encodes.

[stantheman1976]

I prefer this bitrate calculator:
http://dvd-hq.info/Calculator.html

Encode your intro clip independently and in the "Other Assets" field of this calculator put the size of that intro file in there. It will then give you a bitrate that leaves enough room for your clip.

[gadgetguy]

Thanks guys, but I must not have asked my question very well, so let me try to clarify.

The vHelp BC uses 92MB to account for authoring overhead, and by default 25MB for the file structure and other files. I authored a DVD using the default settings and recommended bitrate for the video. The resulting file structure is too large to fit on a SL Disk. I'm assuming the larger menu video file that I'm using is causing the overhead to exceed the reserved 92MB. So I am attempting to determine the actual amount of overhead required. The main folder has only the Audio_TS and Video_TS folders. The Audio_TS folder is empty and the Video_TS contains the following:
VIDEO_TS.BUP - 14KB
VIDEO_TS.IFO - 14KB
VIDEO_TS.VOB - 41,800KB (Menu video)
VTS_01_0.BUP - 46KB
VTS_01_0.IFO - 46KB
VTS_02_0.BUP - 48KB
VTS_02_0.IFO - 48KB
plus the VOBs for the videos themselves.
I am adding up the above to determine the overhead, but it only comes up to a little under 42MB.
There are no subs or additional audio streams or anything extra. Just a main menu with the options for each episode and a play all, and several chapter points per episode, set every 5 minutes, all of which should be accounted for in the IFO and BUP files.

What am I missing?

Edit: OK, there appears to be a huge difference between the source files (m2v and ac3) and the VOBs to the tune of about 28MB per episode. I'm not using subs or additional audio streams or anything else. Can you tell me what accounts for a 28MB difference?

[manono]

Hi-

A while back borax posted about how to figure out the overhead:

https://forum.videohelp.com/viewtopic.php?t=278684

[gadgetguy]

Thanks manono. And thank you borax, where ever you are.