[FFmpeg-devel] PixFmtInfo cleanup

[Michael Niedermayer]

On Thu, Mar 05, 2009 at 12:01:31AM +0100, Stefano Sabatini wrote:
> On date Wednesday 2009-03-04 22:45:28 +0100, Stefano Sabatini encoded:
> > On date Tuesday 2009-02-24 02:13:08 +0100, Michael Niedermayer encoded:
> > > in svn
> [...] 
> > Nice, just one maybe silly question, why all these minus1/plus1?
> 
> I just figured out i myslef, I suppose is to spare bits.
> 
> Next one is: why then offset_plus1?

because we need a -1 somewhere


>  
> > And simple patch attached.
> > -- 
> > FFmpeg = Fast and Frightening Meaningless Powerful Embarassing God
> 
> > Index: libavcodec/pixdesc.h
> > ===================================================================
> > --- libavcodec/pixdesc.h	(revision 17811)
> > +++ libavcodec/pixdesc.h	(working copy)
> > @@ -27,7 +27,7 @@
> >      uint16_t plane        :2;            ///< which of the 4 planes contains the component
> >      uint16_t step_minus1  :3;            ///< number of bytes between 2 horizontally consecutive pixels minus 1
> >      uint16_t offset_plus1 :3;            ///< number of bytes before the component of the first pixel plus 1
> > -    uint16_t shift        :3;            ///< number of lsb that must be shifted away to get the value
> > +    uint16_t shift        :3;            ///< number of least significant bits that must be shifted away to get the value
> >      uint16_t depth_minus1 :4;            ///< number of bits in the component minus 1
> >  }AVComponentDescriptor;
> 
> What if we need to shift away instead some of the *most* significant
> bits (PIX_FMT_BGR555 is the only format I can use as an example)?
> 
> Maybe just another shift_msb field?

we have depth

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I hate to see young programmers poisoned by the kind of thinking
Ulrich Drepper puts forward since it is simply too narrow -- Roman Shaposhnik
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