Calculating VBR - Is there a way

[steptoe]

Can anybody suggest a formula, or calculator or util that can work out in a similiar way to the BitRate Calc on here to get the best VBR for a given movie length ??

At present, I do it by getting the CBR from BitRate Calc, then use that as my average bitrate, then normally use 2000 for the minimum bitrate and either 6000 or 8000 for the maximum bitrate

Snag is, as its variable, then the filelength is not how I calculated (obviously), hence it takes up less room on a DVD-R, hence the quality will be less than upping the average bitrate (I use 2 movies per DVD-R, more if its an episode disk)

I calculate the bitrate from giving half the DVD-R size to each movie, roughly 2250MB per movie including the audio (set at 128k instead of 224k), but using VBR it averages out anything from 1.2GB to 1.8GB depending on how much can be squeezed out of the movie being encoded

I want it as close to that 2250MB limit as possible so giving a higher VBR, so giving the movie more bitrate to play with when encoding, which is very easy to do calculate with CBR, but means the encoder can't give more bitrate to the complex parts and less to the simple parts. Hence why I use VBR

I use MCE 1.4.1, as it does exactly what I want, and don't have to wait about 10-12 hours when using TMPGenc Plus. It usually takes less than 3 hours when using 2-pass encoding


I don't mind running the movie through a util if it will mean getting the best VBR I can at the end of the scan




Does this gobblydegook message make sense to anybody, who can help ...........

[bugster]

If you use the value from the bitrate calculator as your average, then the max and min should not matter.

No encoder is perfect in the way it handles these settings and the final filesize may vary slightly from that calculated, and the avergae bitrate in the final mpeg may be slightly out from thta required, but it is usually pretty close. I always err on the side of caution and round down the bitrate suggested to the nearest 250Kbps, just to be on the safe side.

[funkguy4]

mainconcept comes out with lower quality compared to TMPGEnc in my experience. However, do as you wish, if it works for you, then I envy you. VBR calc u can just use some calculator to figure out what the CBR would be and then like put a lot of leeway and set the min to some really small number and the max to something a little higher than the CBR calc's output.