diff options
| -rw-r--r-- | .hgignore | 2 | ||||
| -rw-r--r-- | v4l2-apps/test/v4l2grab.c | 2 | ||||
| -rw-r--r-- | v4l2-spec/Makefile | 16 | ||||
| -rw-r--r-- | v4l2-spec/libv4l.sgml | 168 | ||||
| -rw-r--r-- | v4l2-spec/v4l2.sgml | 38 |
5 files changed, 222 insertions, 4 deletions
@@ -66,6 +66,8 @@ v4l2-spec/capture.c.sgml$ v4l2-spec/entities.sgml$ v4l2-spec/.*\.stamp$ v4l2-spec/indices.sgml$ +v4l2-spec/libv4l-fmt.sgml$ +v4l2-spec/v4l2grab.c.sgml$ v4l2-spec/v4l2-single$ v4l2-spec/v4l2$ v4l2-spec/v4l2.pdf$ diff --git a/v4l2-apps/test/v4l2grab.c b/v4l2-apps/test/v4l2grab.c index 153a0dd30..de921874b 100644 --- a/v4l2-apps/test/v4l2grab.c +++ b/v4l2-apps/test/v4l2grab.c @@ -1,5 +1,5 @@ /* V4L2 video picture grabber - Copyright (C) 2006 Mauro Carvalho Chehab <mchehab@infradead.org> + Copyright (C) 2009 Mauro Carvalho Chehab <mchehab@infradead.org> This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by diff --git a/v4l2-spec/Makefile b/v4l2-spec/Makefile index 8f40e8614..616445137 100644 --- a/v4l2-spec/Makefile +++ b/v4l2-spec/Makefile @@ -5,6 +5,7 @@ SHELL=/bin/bash SGMLS = \ biblio.sgml \ capture.c.sgml \ + v4l2grab.c.sgml \ common.sgml \ compat.sgml \ controls.sgml \ @@ -20,6 +21,7 @@ SGMLS = \ dev-sliced-vbi.sgml \ dev-teletext.sgml \ driver.sgml \ + libv4l.sgml \ entities.sgml \ fdl-appendix.sgml \ func-close.sgml \ @@ -323,6 +325,12 @@ DOCUMENTED = \ -e "s/\(V4L2_PIX_FMT_[A-Z0-9_]\+\) /<link linkend=\"\1\">\1<\/link> /g" \ -e ":a;s/\(linkend=\".*\)_\(.*\">\)/\1-\2/;ta" +libv4l-fmt.sgml: + cat ../v4l2-apps/libv4l/libv4lconvert/*.c| \ + perl -ne 'if (m/(V4L2_PIX_FMT_[^\s\;\\)\,:]+)/) { printf "<link linkend=\"$$1\"><constant>$$1</constant></link>,\n"; };' \ + |sort|uniq| \ + sed -e ":a;s/\(linkend=\".*\)_\(.*\">\)/\1-\2/;ta" > $@ + capture.c.sgml: ../v4l2-apps/test/capture-example.c Makefile echo "<programlisting>" > $@ expand --tabs=8 < $< | \ @@ -330,6 +338,13 @@ capture.c.sgml: ../v4l2-apps/test/capture-example.c Makefile sed 's/i\.e\./&ie;/' >> $@ echo "</programlisting>" >> $@ +v4l2grab.c.sgml: ../v4l2-apps/test/v4l2grab.c Makefile + echo "<programlisting>" > $@ + expand --tabs=8 < $< | \ + sed $(ESCAPE) $(DOCUMENTED) | \ + sed 's/i\.e\./&ie;/' >> $@ + echo "</programlisting>" >> $@ + videodev2.h.sgml: ../linux/include/linux/videodev2.h Makefile echo "<programlisting>" > $@ expand --tabs=8 < $< | \ @@ -488,6 +503,7 @@ distclean clean: rm -f *.stamp rm -f videodev2.h.sgml rm -f capture.c.sgml + rm -f v4l2grab.c.sgml rm -f capture rm -f indices.sgml entities.sgml rm -rf v4l2 v4l2-single v4l2.pdf diff --git a/v4l2-spec/libv4l.sgml b/v4l2-spec/libv4l.sgml new file mode 100644 index 000000000..ec1f8b6fe --- /dev/null +++ b/v4l2-spec/libv4l.sgml @@ -0,0 +1,168 @@ +<title>Libv4l Userspace Library</title> +<section id="libv4l-introduction"> + <title>Introduction</title> + + <para>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.</para> +<para>An example of using libv4l is provided by +<link linkend='v4l2grab-example'>v4l2grab</link>. +</para> + + <para>libv4l consists of 3 different libraries:</para> + <section> + <title>libv4lconvert</title> + + <para>libv4lconvert is a library that converts several +different pixelformats found in V4L2 drivers into a few common RGB and +YUY formats.</para> + <para>It currently accepts the following V4L2 driver formats: +<link linkend="V4L2-PIX-FMT-BGR24"><constant>V4L2_PIX_FMT_BGR24</constant></link>, +<link linkend="V4L2-PIX-FMT-HM12"><constant>V4L2_PIX_FMT_HM12</constant></link>, +<link linkend="V4L2-PIX-FMT-JPEG"><constant>V4L2_PIX_FMT_JPEG</constant></link>, +<link linkend="V4L2-PIX-FMT-MJPEG"><constant>V4L2_PIX_FMT_MJPEG</constant></link>, +<link linkend="V4L2-PIX-FMT-MR97310A"><constant>V4L2_PIX_FMT_MR97310A</constant></link>, +<link linkend="V4L2-PIX-FMT-OV511"><constant>V4L2_PIX_FMT_OV511</constant></link>, +<link linkend="V4L2-PIX-FMT-OV518"><constant>V4L2_PIX_FMT_OV518</constant></link>, +<link linkend="V4L2-PIX-FMT-PAC207"><constant>V4L2_PIX_FMT_PAC207</constant></link>, +<link linkend="V4L2-PIX-FMT-PJPG"><constant>V4L2_PIX_FMT_PJPG</constant></link>, +<link linkend="V4L2-PIX-FMT-RGB24"><constant>V4L2_PIX_FMT_RGB24</constant></link>, +<link linkend="V4L2-PIX-FMT-SBGGR8"><constant>V4L2_PIX_FMT_SBGGR8</constant></link>, +<link linkend="V4L2-PIX-FMT-SGBRG8"><constant>V4L2_PIX_FMT_SGBRG8</constant></link>, +<link linkend="V4L2-PIX-FMT-SGRBG8"><constant>V4L2_PIX_FMT_SGRBG8</constant></link>, +<link linkend="V4L2-PIX-FMT-SN9C10X"><constant>V4L2_PIX_FMT_SN9C10X</constant></link>, +<link linkend="V4L2-PIX-FMT-SN9C20X-I420"><constant>V4L2_PIX_FMT_SN9C20X_I420</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA501"><constant>V4L2_PIX_FMT_SPCA501</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA505"><constant>V4L2_PIX_FMT_SPCA505</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA508"><constant>V4L2_PIX_FMT_SPCA508</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA561"><constant>V4L2_PIX_FMT_SPCA561</constant></link>, +<link linkend="V4L2-PIX-FMT-SQ905C"><constant>V4L2_PIX_FMT_SQ905C</constant></link>, +<constant>V4L2_PIX_FMT_SRGGB8</constant>, +<link linkend="V4L2-PIX-FMT-UYVY"><constant>V4L2_PIX_FMT_UYVY</constant></link>, +<link linkend="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></link>, +<link linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link>, +<link linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link>, +and <link linkend="V4L2-PIX-FMT-YVYU"><constant>V4L2_PIX_FMT_YVYU</constant></link>. +</para> + <para>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.</para> + + <para>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.</para> + + <para>libv4lconvert/processing offers the actual video +processing functionality.</para> + </section> + <section> + <title>libv4l1</title> + <para>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.</para> + <para>Since those functions are emulations of the old V4L1 API, +it shouldn't be used for new applications.</para> + </section> + <section> + <title>libv4l2</title> + <para>This library should be used for all modern V4L2 +applications.</para> + <para>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.</para> + <para>In most cases, libv4l2 just passes the calls directly +through to the v4l2 driver, intercepting the calls to +<link linkend='VIDIOC-G-FMT'><constant>VIDIOC_TRY_FMT</constant></link>, +<link linkend='VIDIOC-G-FMT'><constant>VIDIOC_G_FMT</constant></link> +<link linkend='VIDIOC-G-FMT'><constant>VIDIOC_S_FMT</constant></link> +<link linkend='VIDIOC-ENUM-FRAMESIZES'><constant>VIDIOC_ENUM_FRAMESIZES</constant></link> +and +<link linkend='VIDIOC-ENUM-FRAMEINTERVALS'><constant>VIDIOC_ENUM_FRAMEINTERVALS</constant></link> +in order to emulate the formats +<link linkend="V4L2-PIX-FMT-BGR24"><constant>V4L2_PIX_FMT_BGR24</constant></link>, +<link linkend="V4L2-PIX-FMT-RGB24"><constant>V4L2_PIX_FMT_RGB24</constant></link>, +<link linkend="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></link>, +and <link linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link>, +if they aren't available in the driver. +<link linkend='VIDIOC-ENUM-FMT'><constant>VIDIOC_ENUM_FMT</constant></link> +keeps enumerating the hardware supported formats, plus the emulated formats +offered by libv4l at the end. +</para> + <section id="libv4l-ops"> + <title>Libv4l device control functions</title> + <para>The common file operation methods are provided by +libv4l.</para> + <para>Those functions operate just like glibc +open/close/dup/ioctl/read/mmap/munmap:</para> +<itemizedlist><listitem> + <para>int v4l2_open(const char *file, int oflag, +...) - +operates like the standard <link linkend='func-open'>open()</link> function. +</para></listitem><listitem> + <para>int v4l2_close(int fd) - +operates like the standard <link linkend='func-close'>close()</link> function. +</para></listitem><listitem> + <para>int v4l2_dup(int fd) - +operates like the standard dup() function, duplicating a file handler. +</para></listitem><listitem> + <para>int v4l2_ioctl (int fd, unsigned long int request, ...) - +operates like the standard <link linkend='func-ioctl'>ioctl()</link> function. +</para></listitem><listitem> + <para>int v4l2_read (int fd, void* buffer, size_t n) - +operates like the standard <link linkend='func-read'>read()</link> function. +</para></listitem><listitem> + <para>void v4l2_mmap(void *start, size_t length, int prot, int flags, int fd, int64_t offset); - +operates like the standard <link linkend='func-mmap'>mmap()</link> function. +</para></listitem><listitem> + <para>int v4l2_munmap(void *_start, size_t length); - +operates like the standard <link linkend='func-munmap'>munmap()</link> function. +</para></listitem> +</itemizedlist> + <para>Those functions provide additional control:</para> +<itemizedlist><listitem> + <para>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 <constant>V4L2_DISABLE_CONVERSION</constant>, +to disable format conversion. +</para></listitem><listitem> + <para>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. +</para></listitem><listitem> + <para>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 occured 0 is returned. +</para></listitem> +</itemizedlist> + </section> + </section> + <section> + + <title>v4l1compat.so wrapper library</title> + + <para>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.</para> + <para>It allows usage of binary legacy applications that +still don't use libv4l.</para> + </section> + +</section> +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/v4l2-spec/v4l2.sgml b/v4l2-spec/v4l2.sgml index bae7eb441..8e7610685 100644 --- a/v4l2-spec/v4l2.sgml +++ b/v4l2-spec/v4l2.sgml @@ -25,7 +25,7 @@ <book id="v4l2spec"> <bookinfo> <title>Video for Linux Two API Specification</title> - <subtitle>Revision 0.26</subtitle> + <subtitle>Revision 0.27</subtitle> <authorgroup> <author> @@ -92,6 +92,18 @@ MPEG stream embedded, sliced VBI data format in this specification. </author> </authorgroup> + <author> + <firstname>Mauro</firstname> + <surname>Carvalho Chehab</surname> + <contrib>Documented libv4l, designed and added v4l2grab example + </contrib> + <affiliation> + <address> + <email>mchehab@redhat.com</email> + </address> + </affiliation> + </author> + <copyright> <year>1999</year> <year>2000</year> @@ -105,12 +117,13 @@ MPEG stream embedded, sliced VBI data format in this specification. <year>2008</year> <year>2009</year> <holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin -Rubli, Andy Walls</holder> +Rubli, Andy Walls, Mauro Carvalho Chehab</holder> </copyright> <legalnotice> <para>This document is copyrighted © 1999-2009 by Bill -Dirks, Michael H. Schimek, Hans Verkuil, Martin Rubli, and Andy Walls.</para> +Dirks, Michael H. Schimek, Hans Verkuil, Martin Rubli, Andy Walls and +Mauro Carvalho Chehab.</para> <para>Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, @@ -131,6 +144,13 @@ structs, ioctls) must be noted in more detail in the history chapter applications. --> <revision> + <revnumber>0.27</revnumber> + <date>2009-08-15</date> + <authorinitials>mcc</authorinitials> + <revremark>Added libv4l documentation and v4l2grab example.</revremark> + </revision> + + <revision> <revnumber>0.26</revnumber> <date>2009-06-15</date> <authorinitials>hv</authorinitials> @@ -471,6 +491,10 @@ available here: <ulink url="http://linuxtv.org/downloads/video4linux/API/V4L2_AP &sub-driver; </chapter> + <chapter id="libv4l"> + &sub-libv4l; + </chapter> + <chapter id="compat"> &sub-compat; </chapter> @@ -485,6 +509,14 @@ available here: <ulink url="http://linuxtv.org/downloads/video4linux/API/V4L2_AP &sub-capture-c; </appendix> + <appendix id="v4l2grab-example"> + <title>Video Grabber example using libv4l</title> + <para>This program demonstrates how to grab V4L2 images in ppm format by +using libv4l handlers. The advantage is that this grabber can potentially work +with any V4L2 driver.</para> + &sub-v4l2grab-c; + </appendix> + &sub-fdl-appendix; &sub-indices; |