Vista / Windows 7中字幕的透明度

private void SetVRM9MixerSettings(int width, int height, int lines)
        {
            int hr = 0;
            VMR9AlphaBitmap alphaBmp;               

            // Set Alpha Bitmap Parameters for using a Direct3D surface
            alphaBmp = new VMR9AlphaBitmap();
            alphaBmp.dwFlags = VMR9AlphaBitmapFlags.EntireDDS | VMR9AlphaBitmapFlags.FilterMode;

            // on unmanagedSurface the bitmap was drawn with transparency
            alphaBmp.pDDS = unmanagedSurface;
            alphaBmp.rDest = GetDestRectangle(width, height, lines);
            alphaBmp.fAlpha = 1.0f;
            alphaBmp.dwFilterMode = VMRMixerPrefs.BiLinearFiltering;

            // for anaglyph half SBS
            if (FrameMode == Mars.FrameMode.HalfSideBySide)
            {
                alphaBmp.rDest.left /= 2;
                alphaBmp.rDest.right /= 2;
            }

            // Set Alpha Bitmap Parameters
            hr = mixerBitmap.SetAlphaBitmap(ref alphaBmp);
            DsError.ThrowExceptionForHR(hr);

        }

 private void SetEVRMixerSettings(int width, int height, int subtitleLines)
        {
            MFVideoAlphaBitmap alphaBmp = new MFVideoAlphaBitmap();

            //alphaBitmap is a 32bit semitransparent Bitmap
            Graphics g = Graphics.FromImage(alphaBitmap);

            // get pointer to needed objects
            IntPtr hdc = g.GetHdc();
            IntPtr memDC = CreateCompatibleDC(hdc);
            IntPtr hBitmap = alphaBitmap.GetHbitmap();
            IntPtr hOld = SelectObject(memDC, hBitmap);

            alphaBmp.GetBitmapFromDC = true;
            alphaBmp.stru = memDC;
            alphaBmp.paras = new MFVideoAlphaBitmapParams();
            alphaBmp.paras.dwFlags = MFVideoAlphaBitmapFlags.Alpha | MFVideoAlphaBitmapFlags.SrcColorKey | MFVideoAlphaBitmapFlags.DestRect;

            // calculate destination rectangle
            MFVideoNormalizedRect mfNRect = new MFVideoNormalizedRect();
            NormalizedRect nRect = GetDestRectangle(width, height, subtitleLines);

            mfNRect.top = nRect.top;
            mfNRect.left = nRect.left;
            mfNRect.right = nRect.right;
            mfNRect.bottom = nRect.bottom;

            // used when viewing half side by side anaglyph video that is stretched to full width
            if (FrameMode == Mars.FrameMode.HalfSideBySide)
            {
                mfNRect.left /= 2;
                mfNRect.right /= 2;
            } 

            alphaBmp.paras.nrcDest = mfNRect;

            // calculate source rectangle (full subtitle bitmap)
            MFRect rcSrc = new MFRect();
            rcSrc.bottom = alphaBitmap.Height;
            rcSrc.right = alphaBitmap.Width;
            rcSrc.top = 0;
            rcSrc.left = 0;

            alphaBmp.paras.rcSrc = rcSrc;

            // apply 1-bit transparency 
            System.Drawing.Color colorKey = System.Drawing.Color.Black;
            alphaBmp.paras.clrSrcKey = ColorTranslator.ToWin32(colorKey);

            // 90% visible
            alphaBmp.paras.fAlpha = 0.9F;

            // set the bitmap to the evr mixer
            evrMixerBitmap.SetAlphaBitmap(alphaBmp);

            // cleanup
            SelectObject(memDC, hOld);
            DeleteDC(memDC);
            g.ReleaseHdc();

        }