Add option to leave settings unchanged in v4l2 input.

This adds an additional option for all settings to leave the current
configuration of the device unchanged.

plugins/linux-v4l2/data/locale/en-US.ini

@@ -4,3 +4,4 @@ Input="Input"
 ImageFormat="Video Format"
 Resolution="Resolution"
 FrameRate="Frame Rate"
+LeaveUnchanged="Leave Unchanged"

plugins/linux-v4l2/v4l2-input.c

@@ -205,11 +205,10 @@ static const char* v4l2_getname(void)
 
 static void v4l2_defaults(obs_data_t settings)
 {
-	obs_data_set_default_int(settings, "input", 0);
-	obs_data_set_default_int(settings, "pixelformat", V4L2_PIX_FMT_YUYV);
-	obs_data_set_default_int(settings, "resolution",
-			pack_tuple(640, 480));
-	obs_data_set_default_int(settings, "framerate", pack_tuple(1, 30));
+	obs_data_set_default_int(settings, "input", -1);
+	obs_data_set_default_int(settings, "pixelformat", -1);
+	obs_data_set_default_int(settings, "resolution", -1);
+	obs_data_set_default_int(settings, "framerate", -1);
 }
 
 /*
@@ -287,6 +286,8 @@ static void v4l2_input_list(int_fast32_t dev, obs_property_t prop)
 
 	obs_property_list_clear(prop);
 
+	obs_property_list_add_int(prop, obs_module_text("LeaveUnchanged"), -1);
+
 	while (v4l2_ioctl(dev, VIDIOC_ENUMINPUT, &in) == 0) {
 		if (in.type & V4L2_INPUT_TYPE_CAMERA) {
 			obs_property_list_add_int(prop, (char *) in.name,
@@ -311,6 +312,8 @@ static void v4l2_format_list(int dev, obs_property_t prop)
 
 	obs_property_list_clear(prop);
 
+	obs_property_list_add_int(prop, obs_module_text("LeaveUnchanged"), -1);
+
 	while (v4l2_ioctl(dev, VIDIOC_ENUM_FMT, &fmt) == 0) {
 		dstr_copy(&buffer, (char *) fmt.description);
 		if (fmt.flags & V4L2_FMT_FLAG_EMULATED)
@@ -346,6 +349,8 @@ static void v4l2_resolution_list(int dev, uint_fast32_t pixelformat,
 
 	obs_property_list_clear(prop);
 
+	obs_property_list_add_int(prop, obs_module_text("LeaveUnchanged"), -1);
+
 	v4l2_ioctl(dev, VIDIOC_ENUM_FRAMESIZES, &frmsize);
 
 	switch(frmsize.type) {
@@ -392,6 +397,8 @@ static void v4l2_framerate_list(int dev, uint_fast32_t pixelformat,
 
 	obs_property_list_clear(prop);
 
+	obs_property_list_add_int(prop, obs_module_text("LeaveUnchanged"), -1);
+
 	v4l2_ioctl(dev, VIDIOC_ENUM_FRAMEINTERVALS, &frmival);
 
 	switch(frmival.type) {