VBI Surface Allocator

Microsoft DirectShow 9.0

VBI Surface Allocator

The VBI Surface Allocator controls the allocation of VBI buffers in analog television graphs with hardware video port capture scenarios. With devices such as the Bt829 decoder, the frame buffer may contain multiple VBI capture buffers that are accessed via a proprietary hardware-based mechanism known generically as a Video Port. The VBI Surface Allocator filter connects downstream from the capture filter and has no output pin. The filter works closely with the Overlay Mixer (via DirectDraw) to perform coordinated operations on the hardware video port, utilizing the same limited SVGA frame buffer memory.

Filter Interfaces IBaseFilter
Input Pin Interfaces IKsPropertySet
Output Pin Media Types MEDIATYPE_NULL, MEDIASUBTYPE_NULL. (Nothing is ever connected to the output pin.)
Output Pin Interfaces Not applicable.
Filter CLSID CLSID_VBISurfaces
Property Page CLSID No property page.
Executable vbisurf.ax
Filter Category CLSID_LegacyAmFilterCategory


On Windows 98SE and Windows 2000, the VBI Surface Allocator does not support video port connections on secondary monitors. The pin connection will fail in this case. This limitation does not exist on Windows Me or Windows XP.

See Also