[FFmpeg-devel] PixFmtInfo cleanup

[Stefano Sabatini]

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?
 
> 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?

And BTW, I volunteer for this cleanup (but I have not so much time
lately, sorry), this looks required by lavfi anyway.

Regards.
-- 
FFmpeg = Fostering and Faithless Magical Prodigious Esoteric Geek