On Sunday 04 March 2007 20:42, you wrote:
> > int uv_dst_offset = ucdev->dst_offset + (ucdev->dst_pitch * rect->h);
> > int uv_src_offset = ucdev->src_offset + (ucdev->src_pitch * rect->h);
> >
> > If rect is the source rect which should be blitted then:
static bool uc_blit_planar(void* drv, void* dev, DFBRectangle* rect, int dx,
int dy)
My analysis is only correct if parameter rect is the source rectangle
which should be blitted.
> > - destination offset of y plane should be advanced by dst_pitch * dy.
> > - dest offset of 1st uv plane is dst_offset + dest_pitch * dst_high +
> > (dst_pitch * dy) / 4.
> > - dest offset of 2nd uv plane is (dest_pitch * dst_high) / 4 past 1st
> > plane offset.
>
>
> I can believe there could be a bug in the blitting of planar surfaces but I
> don't follow your analysis. dst_offset is simply the memory location of
> start of the surface image data. uv_dst_offset holds the memory location of
> the start of the first chrominance plane's image data (and is subsequently
> adjusted to point to the second). What further correction to these values
> is needed and why?
For destination pointer calculation, the height of the source rectangle is out
of interest.
>
> The existing code in uc_blit_planar adjusts the rectangle and pitch values
> when it blits the chrominance planes.
>
> Perhaps we could rewind a bit and you could describe what's actually going
> wrong?
Ok, I've to explain a bit more.
The source surface holds data which is decoded by the via mpeg hw-decoder
and is for expample of size 720x576. I want to crop out a 16:9 area of the 4:3
video frame. The cropped area should be taken from line 72 with height 432
from source, and blitted to x=0 and y=0 to the destination surface.
Hm, dest surface is in my case of height: source rect-height, so it should fit.
But the source u plane does not start at src_offset + (src_pitch * rect->h)
softdevice in case we cannot use SetSourceRectangle() ;-) .
Additional cutXXX are zero in my case.
sRect.x = sxoff + 2 * cutLeft;
sRect.y = syoff + 2 * cutTop;
sRect.w = swidth - 2 * (cutLeft + cutRight);
sRect.h = sheight - 2 * (cutTop + cutBottom);
videoSurface->Blit(mpegfb[currentFB], &sRect, cutLeft * 2, cutTop * 2);
--
Stefan Lucke
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