From 0fb6ec6b1c185a1d99bf238880cc265d72ab111b Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Mon, 7 Nov 2011 08:30:20 -0300 Subject: [PATCH] [media] V4L2 Spec: clarify usage of V4L2_FBUF_FLAG_PRIMARY As per discussion during the 2011 V4L-DVB workshop. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/media/v4l/vidioc-g-fbuf.xml | 10 ++++++---- 1 file 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. 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. +non-destructive overlays. Video Output Overlays are in practice always +non-destructive. V4L2_FBUF_CAP_CHROMAKEY @@ -356,7 +357,9 @@ with the chroma-key colors are replaced by video pixels, which is exactly opposi V4L2_FBUF_FLAG_PRIMARY 0x0001 The framebuffer is the primary graphics surface. -In other words, the overlay is destructive. [?] +In other words, the overlay is destructive. This flag is typically set by any +driver that doesn't have the V4L2_FBUF_CAP_EXTERNOVERLAY +capability and it is cleared otherwise. V4L2_FBUF_FLAG_OVERLAY @@ -366,9 +369,8 @@ size as the capture. [?] The purpose of -V4L2_FBUF_FLAG_PRIMARY and V4L2_FBUF_FLAG_OVERLAY 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 bttv driver applications should set the V4L2_FBUF_FLAG_OVERLAY flag.