v4l2-library: libv4l2 and v4l2convert

From: Hans de Goede <j.w.r.degoede at hhs.nl>

libv4l2 offers v4l2_ prefixed versions of
   open/close/etc. The API is 100% the same as directly opening /dev/videoX
   using regular open/close/etc, the big difference is that format conversion
   is done if necessary when capturing. That is if you (try to) set a capture
   format which is not supported by the cam, but is supported by libv4lconvert,
   then the try_fmt / set_fmt will succeed as if the cam supports the format
   and on dqbuf / read the data will be converted for you and returned in
   the request format.
v4l2convert: open/close/ioctl/mmap/munmap library call wrapper doing format conversion
   for v4l2 applications which want to be able to simply capture bgr24 / yuv420
   from v4l2 devices with more exotic frame formats.

Signed-off-by: Hans de Goede <j.w.r.degoede at hhs.nl>
Signed-off-by: Thierry MERLE <thierry.merle@free.fr>

1 files changed, 94 insertions, 0 deletions

diff --git a/v4l2-apps/lib/libv4l/libv4l2/libv4l2-priv.h b/v4l2-apps/lib/libv4l/libv4l2/libv4l2-priv.h
new file mode 100644
index 000000000..bdbd45e5c
--- /dev/null
+++ b/v4l2-apps/lib/libv4l/libv4l2/libv4l2-priv.h
@@ -0,0 +1,94 @@
+/*
+#             (C) 2008 Hans de Goede <j.w.r.degoede@hhs.nl>
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifndef __LIBV4L2_PRIV_H
+#define __LIBV4L2_PRIV_H
+
+#include <stdio.h>
+#include <pthread.h>
+#include <libv4lconvert.h> /* includes videodev2.h for us */
+
+#define V4L2_MAX_DEVICES 16
+/* Warning when making this larger the frame_queued and frame_mapped members of
+   the v4l2_dev_info struct can no longer be a bitfield, so the code needs to
+   be adjusted! */
+#define V4L2_MAX_NO_FRAMES 32u
+#define V4L2_DEFAULT_NREADBUFFERS 4
+#define V4L2_FRAME_BUF_SIZE (4096 * 4096)
+
+#define V4L2_LOG_ERR(...) \
+  do { \
+    if (v4l2_log_file) { \
+      fprintf(v4l2_log_file, "libv4l2: error " __VA_ARGS__); \
+      fflush(v4l2_log_file); \
+    } else \
+      fprintf(stderr, "libv4l2: error " __VA_ARGS__); \
+  } while(0)
+
+#define V4L2_LOG_WARN(...) \
+  do { \
+    if (v4l2_log_file) { \
+      fprintf(v4l2_log_file, "libv4l2: warning " __VA_ARGS__); \
+      fflush(v4l2_log_file); \
+    } else \
+      fprintf(stderr, "libv4l2: warning " __VA_ARGS__); \
+  } while(0)
+
+#define V4L2_LOG(...) \
+  do { \
+    if (v4l2_log_file) { \
+      fprintf(v4l2_log_file, "libv4l2: " __VA_ARGS__); \
+      fflush(v4l2_log_file); \
+    } \
+  } while(0)
+
+#define MIN(a,b) (((a)<(b))?(a):(b))
+
+enum v4l2_io { v4l2_io_none, v4l2_io_read, v4l2_io_mmap };
+
+struct v4l2_dev_info {
+  int fd;
+  int flags;
+  int open_count;
+  /* actually format of the cam */
+  struct v4l2_format src_fmt;
+  /* fmt as seen by the application (iow after conversion) */
+  struct v4l2_format dest_fmt;
+  pthread_mutex_t stream_lock;
+  unsigned int no_frames;
+  unsigned int nreadbuffers;
+  enum v4l2_io io;
+  struct v4lconvert_data *convert;
+  unsigned char *convert_mmap_buf;
+  /* Frame bookkeeping is only done when in read or mmap-conversion mode */
+  unsigned char *frame_pointers[V4L2_MAX_NO_FRAMES];
+  int frame_sizes[V4L2_MAX_NO_FRAMES];
+  int frame_queued; /* 1 status bit per frame */
+  /* mapping tracking of our fake (converting mmap) frame buffers, todo this
+     perfect we should use a map counter per frame, this is a good
+     approximation but there are scenarios thinkable where this doesn't work.
+     However no normal application not even a buggy one is likely to exhibit
+     the patterns needed to fail this somewhat simplified tracking */
+  int frame_mapped; /* 1 status bit per frame */
+  int frame_map_count; /* total number of maps of (fake) buffers combined */
+};
+
+/* From log.c */
+void v4l2_log_ioctl(unsigned long int request, void *arg, int result);
+
+#endif