Commit 05834fcf authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab

[media] v4l2 spec: clarify usage of V4L2_FBUF_FLAG_OVERLAY

Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 0cb64f02
...@@ -364,15 +364,20 @@ capability and it is cleared otherwise.</entry> ...@@ -364,15 +364,20 @@ capability and it is cleared otherwise.</entry>
<row> <row>
<entry><constant>V4L2_FBUF_FLAG_OVERLAY</constant></entry> <entry><constant>V4L2_FBUF_FLAG_OVERLAY</constant></entry>
<entry>0x0002</entry> <entry>0x0002</entry>
<entry>The frame buffer is an overlay surface the same <entry>If this flag is set for a video capture device, then the
size as the capture. [?]</entry> driver will set the initial overlay size to cover the full framebuffer size,
</row> otherwise the existing overlay size (as set by &VIDIOC-S-FMT;) will be used.
<row>
<entry spanname="hspan">The purpose of Only one video capture driver (bttv) supports this flag. The use of this flag
<constant>V4L2_FBUF_FLAG_OVERLAY</constant> was never quite clear. for capture devices is deprecated. There is no way to detect which drivers
Most drivers seem to ignore this flag. For compatibility with the support this flag, so the only reliable method of setting the overlay size is
<wordasword>bttv</wordasword> driver applications should set the through &VIDIOC-S-FMT;.
<constant>V4L2_FBUF_FLAG_OVERLAY</constant> flag.</entry>
If this flag is set for a video output device, then the video output overlay
window is relative to the top-left corner of the framebuffer and restricted
to the size of the framebuffer. If it is cleared, then the video output
overlay window is relative to the video output display.
</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_FBUF_FLAG_CHROMAKEY</constant></entry> <entry><constant>V4L2_FBUF_FLAG_CHROMAKEY</constant></entry>
......
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