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

[Martin Drab]

On Fri, 11 Feb 2005, Martin Drab wrote:

> 
> 
> On Fri, 11 Feb 2005, Diego Biurrun wrote:
> 
> > Martin Drab writes:
> > > 
> > > On Fri, 11 Feb 2005, Andreu Escudero wrote:
> > > 
> > > > Better:
> > > > 1       First pass of multi-pass encoding
> > > > 2       ALERT - Only for 2 pass encodings
> > > >          Second pass of 2 pass encoding
> > > > 3       ALERT - For N pass encodings (where N >= 2)
> > > >          Subsequent passes (2nd and up) of multi-pass encoding
> > > >          The log file is overwriten (refined) for each pass.
> > > 
> > > Even better and IMHO clearer:
> > > 
> > > 1	First pass (only generate log file)
> > > 3	N-th pass (read, refine, and write log file)
> > > 2	Last pass (only read log file)
> > > 
> > > This fits to all cases.
> > 
> > Boulderdash.  Then 2 would come _after_ 3.  How much sense could that
> > make?  None at all.
> 
> The number cannot be swapped without breaking backwards compatibility. 
> Although I have nothing against that. I just think this expressing is the 
> one, that makes the stuff most clear. It really is like that, when you 
> want to do a 3-pass encode, you really have to do pass=1, then pass=3, and 
> then pass=2 !!

We can just say, that the number passed in the pass=... option has nothing 
to do with the actual number of the current pass. It is just an index 
determining what to do, i.e., 1 = wo, 2 = ro, 3 = rw. If you take a look 
at it that way, you may also see it as a binary number, where bit 0 stands 
for writing the log file and bit 1 stands for reading the log file, so
then the numbers and their order would make even more sense:

01 = 1 = First pass (Only write a log file)
11 = 3 = N-th pass (Read, refine, and write a log file)
10 = 2 = Last pass (Only read a log file)

Martin