From 4266129964b8238526936d723de65b419d8069c6 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 31 May 2011 16:27:44 -0300 Subject: [media] DocBook: Move all media docbook stuff into its own directory This patch addresses several issues pointed by Randy Dunlap at changeset ece722c: - In the generated index.html file, "media" is listed first, but it should be listed in alphabetical order, not first. - The generated files are (hidden) in .tmpmedia/ - The link from the top-level index.html file to "media" is to media/index.html, but the file is actually in .tmpmedia/media/index.html - Please build docs with and without using "O=builddir" and test that. - Would it be possible for media to have its own Makefile instead of merging into this one? Due to the way cleandocs target works, I had to rename the media DocBook to media_api, otherwise cleandocs would remove the /media directory. Thanks-to: Randy Dunlap Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/v4l/libv4l.xml | 167 ----------------------------------- 1 file changed, 167 deletions(-) delete mode 100644 Documentation/DocBook/v4l/libv4l.xml (limited to 'Documentation/DocBook/v4l/libv4l.xml') diff --git a/Documentation/DocBook/v4l/libv4l.xml b/Documentation/DocBook/v4l/libv4l.xml deleted file mode 100644 index 3cb10ec51929..000000000000 --- a/Documentation/DocBook/v4l/libv4l.xml +++ /dev/null @@ -1,167 +0,0 @@ -Libv4l Userspace Library -
- Introduction - - libv4l is a collection of libraries which adds a thin abstraction -layer on top of video4linux2 devices. The purpose of this (thin) layer -is to make it easy for application writers to support a wide variety of -devices without having to write separate code for different devices in the -same class. -An example of using libv4l is provided by -v4l2grab. - - - libv4l consists of 3 different libraries: -
- libv4lconvert - - libv4lconvert is a library that converts several -different pixelformats found in V4L2 drivers into a few common RGB and -YUY formats. - It currently accepts the following V4L2 driver formats: -V4L2_PIX_FMT_BGR24, -V4L2_PIX_FMT_HM12, -V4L2_PIX_FMT_JPEG, -V4L2_PIX_FMT_MJPEG, -V4L2_PIX_FMT_MR97310A, -V4L2_PIX_FMT_OV511, -V4L2_PIX_FMT_OV518, -V4L2_PIX_FMT_PAC207, -V4L2_PIX_FMT_PJPG, -V4L2_PIX_FMT_RGB24, -V4L2_PIX_FMT_SBGGR8, -V4L2_PIX_FMT_SGBRG8, -V4L2_PIX_FMT_SGRBG8, -V4L2_PIX_FMT_SN9C10X, -V4L2_PIX_FMT_SN9C20X_I420, -V4L2_PIX_FMT_SPCA501, -V4L2_PIX_FMT_SPCA505, -V4L2_PIX_FMT_SPCA508, -V4L2_PIX_FMT_SPCA561, -V4L2_PIX_FMT_SQ905C, -V4L2_PIX_FMT_SRGGB8, -V4L2_PIX_FMT_UYVY, -V4L2_PIX_FMT_YUV420, -V4L2_PIX_FMT_YUYV, -V4L2_PIX_FMT_YVU420, -and V4L2_PIX_FMT_YVYU. - - Later on libv4lconvert was expanded to also be able to do -various video processing functions to improve webcam video quality. -The video processing is split in to 2 parts: libv4lconvert/control and -libv4lconvert/processing. - - The control part is used to offer video controls which can -be used to control the video processing functions made available by - libv4lconvert/processing. These controls are stored application wide -(until reboot) by using a persistent shared memory object. - - libv4lconvert/processing offers the actual video -processing functionality. -
-
- libv4l1 - This library offers functions that can be used to quickly -make v4l1 applications work with v4l2 devices. These functions work exactly -like the normal open/close/etc, except that libv4l1 does full emulation of -the v4l1 api on top of v4l2 drivers, in case of v4l1 drivers it -will just pass calls through. - Since those functions are emulations of the old V4L1 API, -it shouldn't be used for new applications. -
-
- libv4l2 - This library should be used for all modern V4L2 -applications. - It provides handles to call V4L2 open/ioctl/close/poll -methods. Instead of just providing the raw output of the device, it enhances -the calls in the sense that it will use libv4lconvert to provide more video -formats and to enhance the image quality. - In most cases, libv4l2 just passes the calls directly -through to the v4l2 driver, intercepting the calls to -VIDIOC_TRY_FMT, -VIDIOC_G_FMT -VIDIOC_S_FMT -VIDIOC_ENUM_FRAMESIZES -and VIDIOC_ENUM_FRAMEINTERVALS -in order to emulate the formats -V4L2_PIX_FMT_BGR24, -V4L2_PIX_FMT_RGB24, -V4L2_PIX_FMT_YUV420, -and V4L2_PIX_FMT_YVU420, -if they aren't available in the driver. -VIDIOC_ENUM_FMT -keeps enumerating the hardware supported formats, plus the emulated formats -offered by libv4l at the end. - -
- Libv4l device control functions - The common file operation methods are provided by -libv4l. - Those functions operate just like glibc -open/close/dup/ioctl/read/mmap/munmap: - - int v4l2_open(const char *file, int oflag, -...) - -operates like the standard open() function. - - int v4l2_close(int fd) - -operates like the standard close() function. - - int v4l2_dup(int fd) - -operates like the standard dup() function, duplicating a file handler. - - int v4l2_ioctl (int fd, unsigned long int request, ...) - -operates like the standard ioctl() function. - - int v4l2_read (int fd, void* buffer, size_t n) - -operates like the standard read() function. - - void v4l2_mmap(void *start, size_t length, int prot, int flags, int fd, int64_t offset); - -operates like the standard mmap() function. - - int v4l2_munmap(void *_start, size_t length); - -operates like the standard munmap() function. - - - Those functions provide additional control: - - int v4l2_fd_open(int fd, int v4l2_flags) - -opens an already opened fd for further use through v4l2lib and possibly -modify libv4l2's default behavior through the v4l2_flags argument. -Currently, v4l2_flags can be V4L2_DISABLE_CONVERSION, -to disable format conversion. - - int v4l2_set_control(int fd, int cid, int value) - -This function takes a value of 0 - 65535, and then scales that range to -the actual range of the given v4l control id, and then if the cid exists -and is not locked sets the cid to the scaled value. - - int v4l2_get_control(int fd, int cid) - -This function returns a value of 0 - 65535, scaled to from the actual range -of the given v4l control id. when the cid does not exist, could not be -accessed for some reason, or some error occurred 0 is returned. - - -
-
-
- - v4l1compat.so wrapper library - - This library intercepts calls to -open/close/ioctl/mmap/mmunmap operations and redirects them to the libv4l -counterparts, by using LD_PRELOAD=/usr/lib/v4l1compat.so. It also -emulates V4L1 calls via V4L2 API. - It allows usage of binary legacy applications that -still don't use libv4l. -
- -
- -- cgit v1.2.3-59-g8ed1b