[FFmpeg-devel] discussion around the best way to patch the swscale for Blackfin

[Marc Hoffman]

On 6/14/07, Reimar Doeffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de>
wrote:
>
> Hello,
> On Thu, Jun 14, 2007 at 03:00:44PM -0400, Marc Hoffman wrote:
> [...]
> > What do you mean "doesn't allow to use special bfin converters only for
> some
> > colourspaces"?
>
> I mean that above where you inserted you new code there is e.g.:
> c->swScale= gray16swap;
> With your patch, this gray16swap will never be used for colourspace
> conversion on blackfin, even if you do not have an optimized variant of
> it (unless you also duplicate the selection code for non-optimzed
> conversion in you new function, I can't know that from your patch of
> course ;-) ).



I think we are on the same page.

I guess I was thinking that the  my function could choose to override but it
doesn't need to do that.  The semantics of the function I would define would
be something like this.

SwsFunc ff_bfin_get_unscaled_swscale (SwsContext *c)
{
  SwsFunc swScale = c->swScale;
  if ((c->flags & SWS_CPU_CAPS_BFIN) &&
      ((c->dstFormat == PIX_FMT_YUV420P &&
    (c->srcFormat == PIX_FMT_YUYV422 || c->srcFormat == PIX_FMT_UYVY422))))
{
    return ff_bfin_yuy2toyv12_unscaled;
  }
  return c->swScale;
}


This way I can freely add optimizations for Blackfin with out changing the
existing infastructure. I guess in a sense its much like what the dsputils
do right now.

Maybe I should just do this in swscale

#ifdef ARCH_BFIN
    ff_bfin_get_unscaled_swscale (c);
#endif

And just do the following?

void ff_bfin_get_unscaled_swscale (SwsContext *c)
{
  SwsFunc swScale = c->swScale;
  if ((c->flags & SWS_CPU_CAPS_BFIN) &&
      ((c->dstFormat == PIX_FMT_YUV420P &&
    (c->srcFormat == PIX_FMT_YUYV422 || c->srcFormat == PIX_FMT_UYVY422))))
{
    c->swScale = ff_bfin_yuy2toyv12_unscaled;
  }
}

Now that you came up with a bit of confusion I'm thinking the later might be
a better choice for us.

Marc