From 7b575b6d8de03ca6b6ab85fa1dd53d2ce921a4a0 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Mon, 2 Dec 2019 12:46:17 +0100 Subject: media: vidioc-g-dv-timings.rst: fix wrong porch It is the vfrontporch of field 1 that is one half-line longer, not the backporch. The order of the vertical signals in an interlaced system is: Field 1: vsync vbackporch active video of field 1 vfrontporch + 0.5 Field 2: il_vsync il_vbackporch - 0.5 active video of field 2 il_vfrontporch Interlaced systems that use HALF_LINE set the il_ fields as follows: il_vfrontporch = vfrontporch il_vsync = vsync il_vbackporch = vbackporch + 1 So the total vertical blanking for field 1 is: vsync + vbackporch + vfrontporch + 0.5 and for field 2: vsync + vbackporch + 1 + vfrontporch - 0.5 == vsync + vbackporch + vfrontporch + 0.5 So each field has the same number of half-lines. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/media/uapi') diff --git a/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst index 5712bd48e687..5c675cbac4cf 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst @@ -279,7 +279,7 @@ EBUSY then it will set this flag to signal this to the application. * - ``V4L2_DV_FL_HALF_LINE`` - Specific to interlaced formats: if set, then the vertical - backporch of field 1 (aka the odd field) is really one half-line + frontporch of field 1 (aka the odd field) is really one half-line longer and the vertical backporch of field 2 (aka the even field) is really one half-line shorter, so each field has exactly the same number of half-lines. Whether half-lines can be detected or -- cgit v1.2.3