[MEncoder-users] Adding harddup as an afterthought?

[Rich Felker]

On Mon, Oct 01, 2007 at 09:00:40PM +0000, Ilya Zakharevich wrote:
> [A complimentary Cc of this posting was NOT [per weedlist] sent to
> Reimar =?iso-8859-1?Q?D=F6ffinger?=
> 	
> <mencoder-users at mplayerhq.hu>], who wrote in article <20070929184917.GA26457 at 1und1.de>:
> > >    > > B-frames' mvs are predicted from the following P-frame's mvs.  And
> > >    > > the prediction formula depends on the relative frame numbers, so
> > >    > > inserting a new B-frame would break any existing adjacent B-frames
> > >    > > even if you got the new frame to work.
> 
> > > Let me restate my question: if decoder gets
> 
> > >   P 0 0 0 0 0 0 0 0 0 B P
> 
> > > how should it predict the movements of the B frame?  By 0.5 of
> > > movement of (the second) P, or by 0.9 of it?
> 
> > There is no "0" for the decoder, the decoder gets P B P.
> 
> So the answer is 0.5, which is most probably not very suitable for the
> subject scene...
> 
> Anyway, the last question is: is mencoder doing the correct thing
> (0.5) during ENCODING?

Of course.

> It is very simple to create a bug here...

No, it's impossible. The encoder only sees frames. The zeros ARE NOT
FRAMES!!! They are just a way of indicating in the avi file that no
frame exists at that time. In a format with explicit timestamps they
would not even be present.

Rich