Monday, November 06, 2006

frame buffer bit counts

PlayerFF works in Resolume and Flowmotion, but not in OpenTZT, because OpenTZT passes 24-bit frames to the plugin, even though the screen resolution is 32-bit. The underlying problem is that you can't use DirectDraw to blit between surfaces with different bit counts. I tell my AVI reader (AviToBmp) to uncompress the video into the best format for the display (by passing AVIStreamGetFrameOpen AVIGETFRAMEF_BESTDISPLAYFMT). I use SetSurfaceDesc to turn the video frame into a DirectDraw surface, which means if my display is set for 32 bits, my video frame is also 32 bits, regardless of the actual color depth of the video. That's optimal if the host frame buffers also have the display's bit count, which you would think they would, but in OpenTZT, they don't for some reason, so the blit fails with error E_NOTIMPL.

AVIStreamGetFrameOpen can be also passed a BITMAPINFO that tells it what format to decompress to. This allows me force the the video format to match the host's format, as follows:

ZeroMemory(&bih, sizeof(bih));
bih.biSize = sizeof(bih);
bih.biWidth = m_pBmpInfo->bmiHeader.biWidth;
bih.biHeight = m_pBmpInfo->bmiHeader.biHeight;
bih.biPlanes = 1;
bih.biBitCount = 24; // or whatever host wants
m_pGetFrame = AVIStreamGetFrameOpen(m_pStream, &bih);

Another solution is to just accept that PlayerFF won't work in OpenTZT. Most VJ softwares don't need a player plugin anyway, because they already have elaborate media players built into them. Let's not forget that PlayerFF is primarily designed for use in FFRend!

Another problem: OpenTZT and Flowmotion display PlayerFF's output upside-down, but it looks fine in Resolume and FFRend. Something's pretty wrong there...

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