Quick 1 pass VBR, 2% of target

[jankster]

I've tried a method to get a more accurate target for 1 pass VBR encodes, (I've used CCEquess, it is off too many times). Take your raw m2v (say its 4770 MB) and open/scan it in ReMPEG2, when done write down the AVG value, lets say 5700.

Simple math, 4370MB max on DVD-R, minus 100MB for nav packs, minus 329MB for AC3 (and what ever else). This leaves 3941 for encoded m2v. Take 3941 divided by your raw m2v say 4770 and get .8262 Now multiply the ReMPEG2 avg value of 5700 * .8262 = 4709.

Encode 1 pass VBR
Q-60
MIN=4709
MAX=9000

The resulting encode has come within 1-2% of target many times now. This is not a "lock for sure" working thing, just looks damn good so far. After 10-15 more encodes I will know for sure how accurate it is.

[jankster]

Bach,

Thanks for the reply and math tips.

I'm going to study your link, refine my process, and report back.

[REECYCUP]

im trying to understand this
Encode 1 pass VBR
Q-60
MIN=4709
MAX=9000


1.? wouldnt this give you a very big file
2.1 pass vbr doesnt have a q scale does it?(maybe your not talking cce)

[paul8883]

One pass VBR use Q, Min and Max, but not average bitrate in CCE.

[jankster]

Bach,

Using your formula to calculate the average bitrate, I've found my encodes to come short ~100-150MB of target. Heres why....

1 MB = 1,048,576 bytes X 8 = 8388608 bits

My target values come from Window's Explorer's status bar. If a file is exactly 1,048,576 bytes, the status bar reports 1.00MB, the detailed right window pane reports 1.024MB, and right click/properties reports 1,048,576 bytes.

AVG bitrate = target*8388.608/total_seconds

I'll modify it to this:

AVG bitrate = target*8000/total_seconds

I'm doing more testing now, post results later.