[MPlayer-dev-eng] 3 pass encoding syntax poll

[Loren Merritt]

On Sat, 5 Feb 2005, Loren Merritt wrote:

> When I came up with the current syntax for N-pass encoding with lavc or x264 
> (pass=1 on the first pass, pass=3 on all subsequent), I though it was the 
> most logic method: N-pass simply enables both 1st pass stats file and 2nd 
> pass ratecontrol, so I used 3 == 1|2.
> However, I have seen many confused users, so apparently this isn't so 
> intuitive, and nobody reads the section in the manpage describing its usage.
> So I have decided to change the syntax and/or behavior of multipass encoding. 
> But since I was wrong the first time, I will now ask opinions before choosing 
> a replacement.
>
> * Always perform N-pass encoding. (It is, after all, identical to 2-pass
>  if you run only one Nth pass.)
>
> Additionally (especially in the last option), I think it would be beneficial 
> to use separate statsfiles for each pass, so that cancelling an encode 
> doesn't erase the results of previous passes. This would require changing the 
> -passlogfile option somehow, since there would be multiple files to specify. 
> How best to go about this?

OK, unless there are arguments to the contrary, I will now implement:
Always use N-pass encoding instead of 2-pass.
The statsfilenames will be derived from the value of -passlogfile as:
If the filename contains "%i", replace it with the pass number, else 
append the pass number.

This allows 2-pass encoding with no changes from the current syntax, and 
allows N-pass encoding by simply incrementing vpass.


P.S. If the filename stuff is common to ve_lavc and ve_x264, where should 
it go?

--Loren Merritt