From 670027c507e99521d416994a18a498def9ef2ea3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Sat, 22 Oct 2016 19:31:08 -0300 Subject: Linux-libre 4.8.3-gnu --- Documentation/DocBook/media/v4l/dev-osd.xml | 149 ---------------------------- 1 file changed, 149 deletions(-) delete mode 100644 Documentation/DocBook/media/v4l/dev-osd.xml (limited to 'Documentation/DocBook/media/v4l/dev-osd.xml') diff --git a/Documentation/DocBook/media/v4l/dev-osd.xml b/Documentation/DocBook/media/v4l/dev-osd.xml deleted file mode 100644 index 548533291..000000000 --- a/Documentation/DocBook/media/v4l/dev-osd.xml +++ /dev/null @@ -1,149 +0,0 @@ - Video Output Overlay Interface - Also known as On-Screen Display (OSD) - - Some video output devices can overlay a framebuffer image onto -the outgoing video signal. Applications can set up such an overlay -using this interface, which borrows structures and ioctls of the Video Overlay interface. - - The OSD function is accessible through the same character -special file as the Video Output function. -Note the default function of such a /dev/video device -is video capturing or output. The OSD function is only available after -calling the &VIDIOC-S-FMT; ioctl. - -
- Querying Capabilities - - Devices supporting the Video Output -Overlay interface set the -V4L2_CAP_VIDEO_OUTPUT_OVERLAY flag in the -capabilities field of &v4l2-capability; -returned by the &VIDIOC-QUERYCAP; ioctl. -
- -
- Framebuffer - - Contrary to the Video Overlay -interface the framebuffer is normally implemented on the TV card and -not the graphics card. On Linux it is accessible as a framebuffer -device (/dev/fbN). Given a V4L2 device, -applications can find the corresponding framebuffer device by calling -the &VIDIOC-G-FBUF; ioctl. It returns, amongst other information, the -physical address of the framebuffer in the -base field of &v4l2-framebuffer;. The -framebuffer device ioctl FBIOGET_FSCREENINFO -returns the same address in the smem_start -field of struct fb_fix_screeninfo. The -FBIOGET_FSCREENINFO ioctl and struct -fb_fix_screeninfo are defined in the -linux/fb.h header file. - - The width and height of the framebuffer depends on the -current video standard. A V4L2 driver may reject attempts to change -the video standard (or any other ioctl which would imply a framebuffer -size change) with an &EBUSY; until all applications closed the -framebuffer device. - - - Finding a framebuffer device for OSD - - -#include <linux/fb.h> - -&v4l2-framebuffer; fbuf; -unsigned int i; -int fb_fd; - -if (-1 == ioctl(fd, VIDIOC_G_FBUF, &fbuf)) { - perror("VIDIOC_G_FBUF"); - exit(EXIT_FAILURE); -} - -for (i = 0; i < 30; i++) { - char dev_name[16]; - struct fb_fix_screeninfo si; - - snprintf(dev_name, sizeof(dev_name), "/dev/fb%u", i); - - fb_fd = open(dev_name, O_RDWR); - if (-1 == fb_fd) { - switch (errno) { - case ENOENT: /* no such file */ - case ENXIO: /* no driver */ - continue; - - default: - perror("open"); - exit(EXIT_FAILURE); - } - } - - if (0 == ioctl(fb_fd, FBIOGET_FSCREENINFO, &si)) { - if (si.smem_start == (unsigned long)fbuf.base) - break; - } else { - /* Apparently not a framebuffer device. */ - } - - close(fb_fd); - fb_fd = -1; -} - -/* fb_fd is the file descriptor of the framebuffer device - for the video output overlay, or -1 if no device was found. */ - - -
- -
- Overlay Window and Scaling - - The overlay is controlled by source and target rectangles. -The source rectangle selects a subsection of the framebuffer image to -be overlaid, the target rectangle an area in the outgoing video signal -where the image will appear. Drivers may or may not support scaling, -and arbitrary sizes and positions of these rectangles. Further drivers -may support any (or none) of the clipping/blending methods defined for -the Video Overlay interface. - - A &v4l2-window; defines the size of the source rectangle, -its position in the framebuffer and the clipping/blending method to be -used for the overlay. To get the current parameters applications set -the type field of a &v4l2-format; to -V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY and call the -&VIDIOC-G-FMT; ioctl. The driver fills the -v4l2_window substructure named -win. It is not possible to retrieve a -previously programmed clipping list or bitmap. - - To program the source rectangle applications set the -type field of a &v4l2-format; to -V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY, initialize -the win substructure and call the -&VIDIOC-S-FMT; ioctl. The driver adjusts the parameters against -hardware limits and returns the actual parameters as -VIDIOC_G_FMT does. Like -VIDIOC_S_FMT, the &VIDIOC-TRY-FMT; ioctl can be -used to learn about driver capabilities without actually changing -driver state. Unlike VIDIOC_S_FMT this also works -after the overlay has been enabled. - - A &v4l2-crop; defines the size and position of the target -rectangle. The scaling factor of the overlay is implied by the width -and height given in &v4l2-window; and &v4l2-crop;. The cropping API -applies to Video Output and Video -Output Overlay devices in the same way as to -Video Capture and Video -Overlay devices, merely reversing the direction of the -data flow. For more information see . -
- -
- Enabling Overlay - - There is no V4L2 ioctl to enable or disable the overlay, -however the framebuffer interface of the driver may support the -FBIOBLANK ioctl. -
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