[MEncoder-users] MPEG-2: vrc_minrate and vqmin / lmin

[Corey Hickey]

A. Schmid wrote:
>> 5.  Are all of the options that are noted with (pass 1/2) in the man 
>> disabled if you include them in the second pass? Or can they be 
>> detrimental if you include them on a second pass?
> 
> Generally it's safest (though slow) if pass 2 uses exactly the same 
> parameters as pass 1. Using different parameters can (depending on the 
> parameters) result in inexact statistics.

There's some leeway, though. See the 'turbo' option. Generally, omitting
high-quality options from the first pass will very slightly diminish the
quality of the second pass. It's just yet another trade-off between
quality and CPU time.

Try encoding with three passes if you want to use even more CPU time and
get very slightly better quality.

> I'm not sure what (pass 1/2) means - perhaps it's something to do with 
> pass=3 encodings. Pass=3 works differently, perhaps it just doesn't 
> need/use the parameters marked (pass 1/2)? Anybody know?

That just means they work with pass 1 and pass 2. ...and pass 3, since
three pass encoding was added later.

I can see how that could be confusing. I'm going to send a patch to
remove all instances of '(pass 1/2)'; it's valid to assume that an
option will work on all passes unless marked otherwise.

-Corey