linux-v4l2: Add support for controls

Video4Linux exposes controls for capture devices.  This commit adds
those controls to the properties window for v4l2-input devices.

plugins/linux-v4l2/CMakeLists.txt

@@ -31,6 +31,7 @@ include_directories(
 
 set(linux-v4l2_SOURCES
 	linux-v4l2.c
+	v4l2-controls.c
 	v4l2-input.c
 	v4l2-helpers.c
 	${linux-v4l2-udev_SOURCES}

plugins/linux-v4l2/v4l2-controls.c

@@ -0,0 +1,155 @@
+/*
+Copyright (C) 2019 by Gary Kramlich <[email protected]>
+
+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
+the Free Software Foundation, either version 2 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 General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <fcntl.h>
+
+#include <linux/videodev2.h>
+#include <libv4l2.h>
+
+#include "v4l2-controls.h"
+
+#define blog(level, msg, ...) blog(level, "v4l2-controls: " msg, ##__VA_ARGS__)
+
+#if defined(__i386__)
+#define UINT_TO_POINTER(val) ((void *)(unsigned int)(val))
+#define POINTER_TO_UINT(p) ((unsigned int)(unsigned int)(p))
+#elif defined(__x86_64__)
+#define UINT_TO_POINTER(val) ((void *)(unsigned long)(val))
+#define POINTER_TO_UINT(p) ((unsigned int)(unsigned long)(p))
+#else
+#error "unknown platform, this code won't work"
+#endif
+
+static bool v4l2_control_changed(void *data, obs_properties_t *props,
+				 obs_property_t *prop, obs_data_t *settings)
+{
+	int dev = v4l2_open(obs_data_get_string(settings, "device_id"),
+			    O_RDWR | O_NONBLOCK);
+	bool ret = false;
+
+	(void)props;
+
+	if (dev == -1)
+		return false;
+
+	struct v4l2_control control;
+	control.id = POINTER_TO_UINT(data);
+	control.value = obs_data_get_int(settings, obs_property_name(prop));
+
+	if (0 != v4l2_ioctl(dev, VIDIOC_S_CTRL, &control)) {
+		ret = true;
+	}
+
+	v4l2_close(dev);
+
+	return ret;
+}
+
+static int_fast32_t v4l2_update_controls_menu(int_fast32_t dev,
+					      obs_properties_t *props,
+					      struct v4l2_queryctrl *qctrl)
+{
+	obs_property_t *prop;
+	struct v4l2_querymenu qmenu;
+
+	prop = obs_properties_add_list(props, (char *)qctrl->name,
+				       (char *)qctrl->name, OBS_COMBO_TYPE_LIST,
+				       OBS_COMBO_FORMAT_INT);
+
+	obs_property_set_modified_callback2(prop, v4l2_control_changed,
+					    UINT_TO_POINTER(qctrl->id));
+
+	memset(&qmenu, 0, sizeof(qmenu));
+	qmenu.id = qctrl->id;
+
+	for (qmenu.index = qctrl->minimum;
+	     qmenu.index <= (uint32_t)qctrl->maximum;
+	     qmenu.index += qctrl->step) {
+		if (0 == v4l2_ioctl(dev, VIDIOC_QUERYMENU, &qmenu)) {
+			obs_property_list_add_int(prop, (char *)qmenu.name,
+						  qmenu.value);
+		}
+	}
+
+	return 0;
+}
+
+int_fast32_t v4l2_update_controls(int_fast32_t dev, obs_properties_t *props,
+				  obs_data_t *settings)
+{
+	struct v4l2_queryctrl qctrl;
+	obs_property_t *prop = NULL;
+
+	if (!dev || !props)
+		return -1;
+
+	memset(&qctrl, 0, sizeof(qctrl));
+	qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
+	while (0 == v4l2_ioctl(dev, VIDIOC_QUERYCTRL, &qctrl)) {
+		if (qctrl.flags & V4L2_CTRL_FLAG_DISABLED) {
+			blog(LOG_INFO, "found control %s but it is disabled",
+			     qctrl.name);
+			continue;
+		}
+
+		if (qctrl.flags & V4L2_CTRL_FLAG_READ_ONLY) {
+			blog(LOG_INFO, "found control %s but it is readonly",
+			     qctrl.name);
+			continue;
+		}
+
+		if (qctrl.flags & V4L2_CTRL_FLAG_VOLATILE) {
+			blog(LOG_INFO, "found control %s but it is volatile",
+			     qctrl.name);
+			continue;
+		}
+
+		switch (qctrl.type) {
+		case V4L2_CTRL_TYPE_INTEGER:
+			prop = obs_properties_add_int_slider(
+				props, (char *)qctrl.name, (char *)qctrl.name,
+				qctrl.minimum, qctrl.maximum, qctrl.step);
+			obs_data_set_default_int(settings, (char *)qctrl.name,
+						 qctrl.default_value);
+			obs_property_set_modified_callback2(
+				prop, v4l2_control_changed,
+				UINT_TO_POINTER(qctrl.id));
+			break;
+		case V4L2_CTRL_TYPE_BOOLEAN:
+			prop = obs_properties_add_bool(
+				props, (char *)qctrl.name, (char *)qctrl.name);
+			obs_data_set_default_bool(settings, (char *)qctrl.name,
+						  qctrl.default_value);
+			obs_property_set_modified_callback2(
+				prop, v4l2_control_changed,
+				UINT_TO_POINTER(qctrl.id));
+			break;
+		case V4L2_CTRL_TYPE_MENU:
+		case V4L2_CTRL_TYPE_INTEGER_MENU:
+			v4l2_update_controls_menu(dev, props, &qctrl);
+			obs_data_set_default_int(settings, (char *)qctrl.name,
+						 qctrl.default_value);
+			blog(LOG_INFO, "setting default for %s to %d",
+			     (char *)qctrl.name, qctrl.default_value);
+			break;
+		}
+
+		qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+	}
+
+	return 0;
+}

plugins/linux-v4l2/v4l2-controls.h

@@ -0,0 +1,40 @@
+/*
+Copyright (C) 2019 by Gary Kramlich <[email protected]>
+
+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
+the Free Software Foundation, either version 2 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 General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <obs-module.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Update a devices properties to include all v4l controls that it supports.
+ *
+ * @param dev handle to the v4l2 device
+ * @param props properties for the device
+ * @param data the settings for the source
+ *
+ * @return negative on failure
+ */
+int_fast32_t v4l2_update_controls(int_fast32_t dev, obs_properties_t *props,
+				  obs_data_t *settings);
+
+#ifdef __cplusplus
+}
+#endif

plugins/linux-v4l2/v4l2-input.c

@@ -35,6 +35,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <util/platform.h>
 #include <obs-module.h>
 
+#include "v4l2-controls.h"
 #include "v4l2-helpers.h"
 
 #if HAVE_UDEV
@@ -579,6 +580,7 @@ static bool device_selected(obs_properties_t *props, obs_property_t *p,
 
 	obs_property_t *prop = obs_properties_get(props, "input");
 	v4l2_input_list(dev, prop);
+	v4l2_update_controls(dev, props, settings);
 	v4l2_close(dev);
 
 	obs_property_modified(prop, settings);