The attached file contains the changes that have to be made to the V4L2
spec in order to document the local and global alpha capabilities to
blend/clip the image in an overlay. These changes will go into kernel
2.6.22.
Regards,
Hans
Documentation of local/global alpha fbuf features.
ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF: add the following capabilities to
Table 2 (Frame Buffer Capability Flags):
V4L2_FBUF_CAP_LOCAL_ALPHA 0x0010 The device supports clipping/blending
using the
alpha channel of the framebuffer.
V4L2_FBUF_CAP_GLOBAL_ALPHA 0x0020 The device supports blending through a
single global
alpha value for the whole framebuffer.
And add the following flags to Table 3 (Frame Buffer Flags):
V4L2_FBUF_FLAG_LOCAL_ALPHA 0x0008 Use the local alpha values set in the
alpha channel of
the framebuffer for blending/clipping
the image.
V4L2_FBUF_FLAG_GLOBAL_ALPHA 0x0010 Use the global alpha value to blend the
framebuffer with
the image.
Section 4.2.3 (Setup): change the following:
'A driver may support any (or none) of three clipping methods:'
->
'A driver may support any (or none) of five clipping methods:'
And add the following two clipping methods:
4. The framebuffer has an alpha channel that can be used to clip or blend the
image with the framebuffer.
5. The framebuffer has a single global alpha value that can be used to
blend the image with the framebuffer contents.
Section 4.2.4 (Overlay Window): add the following to Table 4-1 (struct
v4l2_window):
__u8 global_alpha The global alpha value used to blend the image with the
framebuffer.
Only valid if the global alpha feature has been negotiated. A
global alpha
value of 255 means the framebuffer is opaque (the image is
invisible),
a value of 0 means the framebuffer is transparent (only the
image is visible).
_______________________________________________
ivtv-devel mailing list
[email protected]
http://ivtvdriver.org/mailman/listinfo/ivtv-devel
