This way we'll reuse the GstVdp[Video|Output]Buffers if they're of the same
size and chroma-type/rgba-format.
Also remove gst_vdp_output_src_pad_negotiate and set a "setcaps" function on
GstVdpOutputSrcPad instead, leaving negotiation to GstVdpVideoPostProcess.
gst_vdp_output_src_pad_push, gst_vdp_output_src_pad_alloc_buffer and
gst_vdp_output_src_pad_get_device now take a GError parameter to be able to
signal errors to the caller
The library contains GstVdpDevice GstVdpVideoBuffer and GstVdpOutputBuffer. The
library will (apart from the plugins here) be used by the upcoming gst-ffmpeg
vdpau support.
vdpausink is as the name implies a sink which takes vide/x-vdpau-output buffers
and outputs it to the screen.
vdpauvideopostprocess is an element which takes video/x-vdpau-video buffers and
outputs video/x-vdpau-output buffers. The element can also do things like
deinterlacing and other postprocessing but this is not implemented yet.
