[FFmpeg-devel] [PATCH] Define endian variant for PIX_FMT_RGB/BGR_5X5

[Stefano Sabatini]

On date Saturday 2009-03-21 01:38:41 +0100, Michael Niedermayer encoded:
> On Fri, Mar 20, 2009 at 11:59:18PM +0100, Stefano Sabatini wrote:
> > On date Thursday 2009-03-19 01:32:55 +0100, Michael Niedermayer encoded:
> > > On Thu, Mar 19, 2009 at 01:27:45AM +0100, Stefano Sabatini wrote:
> > > > On date Wednesday 2009-03-18 23:48:50 +0100, Michael Niedermayer encoded:
> > > > > On Wed, Mar 18, 2009 at 11:44:58PM +0100, Stefano Sabatini wrote:
> > > > > > On date Wednesday 2009-03-18 22:30:26 +0100, Michael Niedermayer encoded:
> > > > > > > On Tue, Mar 17, 2009 at 09:14:32PM +0100, Stefano Sabatini wrote:
> > > > > > [...]
> > > > > > > > Index: ffmpeg/libavcodec/avcodec.h
> > > > > > > > ===================================================================
> > > > > > > > --- ffmpeg.orig/libavcodec/avcodec.h	2009-03-17 21:06:43.000000000 +0100
> > > > > > > > +++ ffmpeg/libavcodec/avcodec.h	2009-03-17 21:09:56.000000000 +0100
> > > > > > > > @@ -2702,6 +2702,19 @@
> > > > > > > >  const char *avcodec_get_pix_fmt_name(int pix_fmt);
> > > > > > > >  void avcodec_set_dimensions(AVCodecContext *s, int width, int height);
> > > > > > > >  enum PixelFormat avcodec_get_pix_fmt(const char* name);
> > > > > > > > +
> > > > > > > > +/**
> > > > > > > > + * Returns the pixel format corresponding to the name \p name.
> > > > > > > > + *
> > > > > > > > + * If \p search_ne_variant is zero works like avcodec_get_pix_fmt().
> > > > > > > > + * If \p search_ne_variant is non-zero and if there is no pixel format
> > > > > > > > + * with name \p name, then a pixel format with the name corresponding
> > > > > > > > + * to the native endian format of \p name is searched.  For example in
> > > > > > > > + * a little-endian system, first is looked "gray16", then "gray16le".
> > > > > > > > + *
> > > > > > > > + * Finally if both forms are not found, returns \c PIX_FMT_NONE.
> > > > > > > > + */
> > > > > > > > +enum PixelFormat avcodec_get_pix_fmt2(const char* name, int search_ne_variant);
> > > > > > > >  unsigned int avcodec_pix_fmt_to_codec_tag(enum PixelFormat p);
> > > > > > > >  
> > > > > > > >  #define FF_LOSS_RESOLUTION  0x0001 /**< loss due to resolution change */
> > > > > > > 
> > > > > > > i dont see why a API change would be needed if no be/le postfix is used then
> > > > > > > the machine endianness canbe filled in
> > > > > > 
> > > > > > Since we're changing the behaviour of avcodec_get_pix_fmt() then I think
> > > > > > it should be a new function, for example
> > > > > > avcodec_get_pix_fmt("gray16")
> > > > > > 
> > > > > > currently fails with PIX_FMT_NONE, extending it it would return
> > > > > > PIX_FMT_GRAY16XE
> > > > > > 
> > > > > > or we could break compatibility, although the likeliness that this
> > > > > > may create problems are very low.
> > > > > > 
> > > > > 
> > > > > the user asks for gray16 the user gets gray16 i see no problem
> > > > 
> > > > If the user asks for gray16 the user actually gets a failure, changing
> > > > avcodec_get_pix_fmt it will return PIX_FMT_GRAY16[LB]E.
> > > > 
> > > > As I said the problem is more theoretical than practical, but I'd feel
> > > 
> > > as i said tere is no problem
> > > gray16 means gray16 in native endian, one of le/be is native the returned
> > > is what the user asked for
> > 
> > My point was all about to allow the user to bypass a (moderately)
> > fancy function and give her the opportunity to do the simple
> > thing.
> > 
> > Anyway since I can't find for this specific case a realistic case of
> > use for which the new behaviour of avcodec_get_pix_fmt() could be
> > painful, I'll give up.
> > 
> > New patch simply extends the old behaviour, micro is bumped
> > accordingly.
> > 
> > If you prefer I'll split the patch as implementation+documentation.
> 
> [...]
> > @@ -467,6 +467,24 @@
> >      return PIX_FMT_NONE;
> >  }
> >  
> > +enum PixelFormat avcodec_get_pix_fmt(const char* name)
> > +{
> > +#ifdef WORDS_BIGENDIAN
> > +#   define NE "be"
> > +#else
> > +#   define NE "le"
> > +#endif
> > +    enum PixelFormat p = avcodec_get_pix_fmt_internal(name);
> > +
> > +    if (p == PIX_FMT_NONE) {
> > +        char name2[32] = "";
>                           ^^^^^
> ?
> 
> and looks fine otherwise

Applied, regards.
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