//-----------------------------------------------------------------------------
// CorrectAspectRatio
//
// Converts a rectangle from the source's pixel aspect ratio (PAR) to 1:1 PAR.
// Returns the corrected rectangle.
//
// For example, a 720 x 486 rect with a PAR of 9:10, when converted to 1x1 PAR,
// is stretched to 720 x 540.
//-----------------------------------------------------------------------------
private static Rectangle CorrectAspectRatio(Rectangle src, MFRatio srcPAR)
{
// Start with a rectangle the same size as src, but offset to the origin (0,0).
Rectangle rc = new Rectangle(0, 0, src.Right - src.Left, src.Bottom - src.Top);
int rcNewWidth = rc.Right;
int rcNewHeight = rc.Bottom;
if ((srcPAR.Numerator != 1) || (srcPAR.Denominator != 1))
{
// Correct for the source's PAR.
if (srcPAR.Numerator > srcPAR.Denominator)
{
// The source has "wide" pixels, so stretch the width.
rcNewWidth = Kernal32.MulDiv(rc.Right, srcPAR.Numerator, srcPAR.Denominator);
}
else if (srcPAR.Numerator < srcPAR.Denominator)
{
// The source has "tall" pixels, so stretch the height.
rcNewHeight = Kernal32.MulDiv(rc.Bottom, srcPAR.Denominator, srcPAR.Numerator);
}
// else: PAR is 1:1, which is a no-op.
}
rc = new Rectangle(0, 0, rcNewWidth, rcNewHeight);
return(rc);
}
//-------------------------------------------------------------------
// LetterBoxDstRect
//
// Takes a src rectangle and constructs the largest possible
// destination rectangle within the specifed destination rectangle
// such that the video maintains its current shape.
//
// This function assumes that pels are the same shape within both the
// source and destination rectangles.
//
//-------------------------------------------------------------------
private static Rectangle LetterBoxRect(Rectangle rcSrc, Rectangle rcDst)
{
int iDstLBWidth;
int iDstLBHeight;
if (Kernal32.MulDiv(rcSrc.Width, rcDst.Height, rcSrc.Height) <= rcDst.Width)
{
// Column letter boxing ("pillar box")
iDstLBWidth = Kernal32.MulDiv(rcDst.Height, rcSrc.Width, rcSrc.Height);
iDstLBHeight = rcDst.Height;
}
else
{
// Row letter boxing.
iDstLBWidth = rcDst.Width;
iDstLBHeight = Kernal32.MulDiv(rcDst.Width, rcSrc.Height, rcSrc.Width);
}
// Create a centered rectangle within the current destination rect
int left = rcDst.Left + ((rcDst.Width - iDstLBWidth) / 2);
int top = rcDst.Top + ((rcDst.Height - iDstLBHeight) / 2);
Rectangle rc = new Rectangle(left, top, iDstLBWidth, iDstLBHeight);
return(rc);
}