Even if one of downstream d3d11 elements can support dynamic-usage memory,
another one might not support it. Also, to support dynamic-usage,
both upstream and downstream d3d11device must be the same object.
If d3d11colorconvert element is configured, do color space conversion
regardless of the device type whether it's S/W emulation or real H/W.
Since d3d11colorconvert is no more a child of d3d11videosinkbin,
we don't need this behavior. Note that previous code was added to
avoid color space conversion from d3d11videosink if no hardware
device is available (S/W emulation of d3d11 is too slow).
In some cases, rendering and dxgi (e.g., swapchain) APIs should be
called from window message pump thread, but current design (dedicated d3d11 thread)
make it impossible. To solve it, change concurrency model to locking based one
from single-thread model.
D3D11 dynamic texture is a special memory type, which is mainly used for
frequent CPU write access to the texture. For now, this texture type
does not support gst_memory_{map,unmap}
