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Diffstat (limited to 'Documentation/userspace-api/media/v4l/dev-overlay.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/dev-overlay.rst | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/Documentation/userspace-api/media/v4l/dev-overlay.rst b/Documentation/userspace-api/media/v4l/dev-overlay.rst index 7246d560173d..d52977120b41 100644 --- a/Documentation/userspace-api/media/v4l/dev-overlay.rst +++ b/Documentation/userspace-api/media/v4l/dev-overlay.rst @@ -1,11 +1,4 @@ -.. Permission is granted to copy, distribute and/or modify this -.. document under the terms of the GNU Free Documentation License, -.. Version 1.1 or any later version published by the Free Software -.. Foundation, with no Invariant Sections, no Front-Cover Texts -.. and no Back-Cover Texts. A copy of the license is included at -.. Documentation/userspace-api/media/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later .. _overlay: @@ -44,6 +37,10 @@ capturing and overlay. Optionally these drivers may also permit capturing and overlay with a single file descriptor for compatibility with V4L and earlier versions of V4L2. [#f1]_ +A common application of two file descriptors is the X11 +:ref:`Xv/V4L <xvideo>` interface driver and a V4L2 application. +While the X server controls video overlay, the application can take +advantage of memory mapping and DMA. Querying Capabilities ===================== @@ -70,6 +67,7 @@ ioctls must be supported by all video overlay devices. Setup ===== +*Note: support for this has been removed.* Before overlay can commence applications must program the driver with frame buffer parameters, namely the address and size of the frame buffer and the image format, for example RGB 5:6:5. The @@ -95,11 +93,13 @@ A driver may support any (or none) of five clipping/blending methods: 1. Chroma-keying displays the overlaid image only where pixels in the primary graphics surface assume a certain color. -2. A bitmap can be specified where each bit corresponds to a pixel in +2. *Note: support for this has been removed.* + A bitmap can be specified where each bit corresponds to a pixel in the overlaid image. When the bit is set, the corresponding video pixel is displayed, otherwise a pixel of the graphics surface. -3. A list of clipping rectangles can be specified. In these regions *no* +3. *Note: support for this has been removed.* + A list of clipping rectangles can be specified. In these regions *no* video is displayed, so the graphics surface can be seen here. 4. The framebuffer has an alpha channel that can be used to clip or @@ -188,6 +188,7 @@ struct v4l2_window be 0xRRGGBB on a little endian, 0xBBGGRR on a big endian host. ``struct v4l2_clip * clips`` + *Note: support for this has been removed.* When chroma-keying has *not* been negotiated and :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` indicated this capability, applications can set this field to point to an array of clipping @@ -204,6 +205,7 @@ struct v4l2_window are undefined. ``__u32 clipcount`` + *Note: support for this has been removed.* When the application set the ``clips`` field, this field must contain the number of clipping rectangles in the list. When clip lists are not supported the driver ignores this field, its contents @@ -211,6 +213,7 @@ struct v4l2_window supported but no clipping is desired this field must be set to zero. ``void * bitmap`` + *Note: support for this has been removed.* When chroma-keying has *not* been negotiated and :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` indicated this capability, applications can set this field to point to a clipping bit mask. @@ -296,11 +299,6 @@ To start or stop the frame buffer overlay applications call the :ref:`VIDIOC_OVERLAY` ioctl. .. [#f1] - A common application of two file descriptors is the XFree86 - :ref:`Xv/V4L <xvideo>` interface driver and a V4L2 application. - While the X server controls video overlay, the application can take - advantage of memory mapping and DMA. - In the opinion of the designers of this API, no driver writer taking the efforts to support simultaneous capturing and overlay will restrict this ability by requiring a single file descriptor, as in |