diff options
| author | Hans Verkuil | 2011-11-07 08:30:20 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab | 2011-11-25 15:07:22 -0200 |
| commit | 0fb6ec6b1c185a1d99bf238880cc265d72ab111b (patch) | |
| tree | 3a42dbfd3deafd638ce8706e9c362e4e49dd401e /Documentation/DocBook | |
| parent | 146d35b00db270054378de17ca33eb54b0b78311 (diff) | |
[media] V4L2 Spec: clarify usage of V4L2_FBUF_FLAG_PRIMARY
As per discussion during the 2011 V4L-DVB workshop.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml b/Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml index 055718231bc1..109d7294d355 100644 --- a/Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml +++ b/Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml @@ -295,7 +295,8 @@ set this field to zero.</entry> <entry>The device is capable of non-destructive overlays. When the driver clears this flag, only destructive overlays are supported. There are no drivers yet which support both destructive and -non-destructive overlays.</entry> +non-destructive overlays. Video Output Overlays are in practice always +non-destructive.</entry> </row> <row> <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant></entry> @@ -356,7 +357,9 @@ with the chroma-key colors are replaced by video pixels, which is exactly opposi <entry><constant>V4L2_FBUF_FLAG_PRIMARY</constant></entry> <entry>0x0001</entry> <entry>The framebuffer is the primary graphics surface. -In other words, the overlay is destructive. [?]</entry> +In other words, the overlay is destructive. This flag is typically set by any +driver that doesn't have the <constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant> +capability and it is cleared otherwise.</entry> </row> <row> <entry><constant>V4L2_FBUF_FLAG_OVERLAY</constant></entry> @@ -366,9 +369,8 @@ size as the capture. [?]</entry> </row> <row> <entry spanname="hspan">The purpose of -<constant>V4L2_FBUF_FLAG_PRIMARY</constant> and <constant>V4L2_FBUF_FLAG_OVERLAY</constant> was never quite clear. -Most drivers seem to ignore these flags. For compatibility with the +Most drivers seem to ignore this flag. For compatibility with the <wordasword>bttv</wordasword> driver applications should set the <constant>V4L2_FBUF_FLAG_OVERLAY</constant> flag.</entry> </row> |