117 lines
4.6 KiB
C
117 lines
4.6 KiB
C
/*
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# (C) 2008 Hans de Goede <hdegoede@redhat.com>
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
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*/
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#ifndef __LIBV4L2_H
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#define __LIBV4L2_H
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#include <stdio.h>
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#include <unistd.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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#if HAVE_VISIBILITY
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#define LIBV4L_PUBLIC __attribute__ ((visibility("default")))
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#else
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#define LIBV4L_PUBLIC
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#endif
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/* Point this to a FILE opened for writing when you want to log error and
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status messages to a file, when NULL errors will get send to stderr */
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LIBV4L_PUBLIC extern FILE *v4l2_log_file;
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/* Just like your regular open/close/etc, except that format conversion is
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done if necessary when capturing. That is if you (try to) set a capture
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format which is not supported by the cam, but is supported by libv4lconvert,
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then the try_fmt / set_fmt will succeed as if the cam supports the format
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and on dqbuf / read the data will be converted for you and returned in
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the request format. enum_fmt will also report support for the formats to
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which conversion is possible.
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Another difference is that you can make v4l2_read() calls even on devices
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which do not support the regular read() method.
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Note the device name passed to v4l2_open must be of a video4linux2 device,
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if it is anything else (including a video4linux1 device), v4l2_open will
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fail.
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Note that the argument to v4l2_ioctl after the request must be a valid
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memory address of structure of the appropriate type for the request (for
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v4l2 requests which expect a structure address). Passing in NULL or an
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invalid memory address will not lead to failure with errno being EFAULT,
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as it would with a real ioctl, but will cause libv4l2 to break, and you
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get to keep both pieces.
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*/
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LIBV4L_PUBLIC int v4l2_open(const char *file, int oflag, ...);
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LIBV4L_PUBLIC int v4l2_close(int fd);
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LIBV4L_PUBLIC int v4l2_dup(int fd);
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LIBV4L_PUBLIC int v4l2_ioctl(int fd, unsigned long int request, ...);
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LIBV4L_PUBLIC ssize_t v4l2_read(int fd, void *buffer, size_t n);
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LIBV4L_PUBLIC ssize_t v4l2_write(int fd, const void *buffer, size_t n);
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LIBV4L_PUBLIC void *v4l2_mmap(void *start, size_t length, int prot, int flags,
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int fd, int64_t offset);
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LIBV4L_PUBLIC int v4l2_munmap(void *_start, size_t length);
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/* Misc utility functions */
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/* This function takes a value of 0 - 65535, and then scales that range to
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the actual range of the given v4l control id, and then if the cid exists
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and is not locked sets the cid to the scaled value.
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Normally returns 0, even if the cid did not exist or was locked, returns
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non 0 when an other error occurred. */
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LIBV4L_PUBLIC int v4l2_set_control(int fd, int cid, int value);
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/* This function returns a value of 0 - 65535, scaled to from the actual range
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of the given v4l control id. When the cid does not exist, or could not be
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accessed -1 is returned. */
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LIBV4L_PUBLIC int v4l2_get_control(int fd, int cid);
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/* "low level" access functions, these functions allow somewhat lower level
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access to libv4l2 (currently there only is v4l2_fd_open here) */
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/* Flags for v4l2_fd_open's v4l2_flags argument */
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/* Disable all format conversion done by libv4l2, this includes the software
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whitebalance, gamma correction, flipping, etc. libv4lconvert does. Use this
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if you want raw frame data, but still want the additional error checks and
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the read() emulation libv4l2 offers. */
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#define V4L2_DISABLE_CONVERSION 0x01
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/* This flag is *OBSOLETE*, since version 0.5.98 libv4l *always* reports
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emulated formats to ENUM_FMT, except when conversion is disabled. */
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#define V4L2_ENABLE_ENUM_FMT_EMULATION 0x02
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/* v4l2_fd_open: open an already opened fd for further use through
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v4l2lib and possibly modify libv4l2's default behavior through the
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v4l2_flags argument.
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Returns fd on success, -1 if the fd is not suitable for use through libv4l2
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(note the fd is left open in this case). */
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LIBV4L_PUBLIC int v4l2_fd_open(int fd, int v4l2_flags);
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#ifdef __cplusplus
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}
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#endif /* __cplusplus */
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#endif
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