cam: capture_script: Introduce 'loop' property

Add support to the capture script for properties that control the script
execution. Script properties are specified in the 'properties' section
before the actual list of controls specified in the 'frames' section.

Define a first 'loop' property that allows repeating the frame list
periodically. All the frame ids in the 'frames' section shall be smaller
than the loop control.

Modify the capture script example to show usage of the 'loop' property
and better document the frames list while at it.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/cam/capture-script.yaml

@@ -4,6 +4,19 @@
 #
 # A capture script allows to associate a list of controls and their values
 # to frame numbers.
+#
+# The script allows defining a list of frames associated with controls
+# and an optional list of properties that can control the script behaviour.
+
+# properties:
+#   # Repeat the controls every 'idx' frames.
+#   - loop: idx
+#
+# # List of frame number with associated a list of controls to be applied
+# frames:
+#   - frame-number:
+#       Control1: value1
+#       Control2: value2
 
 # \todo Formally define the capture script structure with a schema
 
@@ -12,10 +25,16 @@
 #   libcamera::controls:: enumeration
 # - Controls not supported by the camera currently operated are ignored
 # - Frame numbers shall be monotonically incrementing, gaps are allowed
+# - If a loop limit is specified, frame numbers in the 'frames' list shall be
+#   less than the loop control
+
+# Example: Turn brightness up and down every 460 frames
+
+properties:
+  - loop: 460
 
-# Example:
 frames:
-  - 1:
+  - 0:
       Brightness: 0.0
 
   - 40:
@@ -44,3 +63,9 @@ frames:
 
   - 340:
       Brightness: -0.8
+
+  - 380:
+      Brightness: -0.4
+
+  - 420:
+      Brightness: -0.2

src/cam/capture_script.cpp

@@ -15,7 +15,7 @@ using namespace libcamera;
 
 CaptureScript::CaptureScript(std::shared_ptr<Camera> camera,
 			     const std::string &fileName)
-	: camera_(camera), valid_(false)
+	: camera_(camera), loop_(0), valid_(false)
 {
 	FILE *fh = fopen(fileName.c_str(), "r");
 	if (!fh) {
@@ -44,8 +44,13 @@ CaptureScript::CaptureScript(std::shared_ptr<Camera> camera,
 const ControlList &CaptureScript::frameControls(unsigned int frame)
 {
 	static ControlList controls{};
+	unsigned int idx = frame;
 
-	auto it = frameControls_.find(frame);
+	/* If we loop, repeat the controls every 'loop_' frames. */
+	if (loop_)
+		idx = frame % loop_;
+
+	auto it = frameControls_.find(idx);
 	if (it == frameControls_.end())
 		return controls;
 
@@ -149,7 +154,11 @@ int CaptureScript::parseScript(FILE *script)
 
 		std::string section = eventScalarValue(event);
 
-		if (section == "frames") {
+		if (section == "properties") {
+			ret = parseProperties();
+			if (ret)
+				return ret;
+		} else if (section == "frames") {
 			ret = parseFrames();
 			if (ret)
 				return ret;
@@ -161,6 +170,65 @@ int CaptureScript::parseScript(FILE *script)
 	}
 }
 
+int CaptureScript::parseProperty()
+{
+	EventPtr event = nextEvent(YAML_MAPPING_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	std::string prop = parseScalar();
+	if (prop.empty())
+		return -EINVAL;
+
+	if (prop == "loop") {
+		event = nextEvent();
+		if (!event)
+			return -EINVAL;
+
+		std::string value = eventScalarValue(event);
+		if (value.empty())
+			return -EINVAL;
+
+		loop_ = atoi(value.c_str());
+		if (!loop_) {
+			std::cerr << "Invalid loop limit '" << loop_ << "'"
+				  << std::endl;
+			return -EINVAL;
+		}
+	} else {
+		std::cerr << "Unsupported property '" << prop << "'" << std::endl;
+		return -EINVAL;
+	}
+
+	event = nextEvent(YAML_MAPPING_END_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	return 0;
+}
+
+int CaptureScript::parseProperties()
+{
+	EventPtr event = nextEvent(YAML_SEQUENCE_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	while (1) {
+		if (event->type == YAML_SEQUENCE_END_EVENT)
+			return 0;
+
+		int ret = parseProperty();
+		if (ret)
+			return ret;
+
+		event = nextEvent();
+		if (!event)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 int CaptureScript::parseFrames()
 {
 	EventPtr event = nextEvent(YAML_SEQUENCE_START_EVENT);
@@ -191,6 +259,12 @@ int CaptureScript::parseFrame(EventPtr event)
 		return -EINVAL;
 
 	unsigned int frameId = atoi(key.c_str());
+	if (loop_ && frameId >= loop_) {
+		std::cerr
+			<< "Frame id (" << frameId << ") shall be smaller than"
+			<< "loop limit (" << loop_ << ")" << std::endl;
+		return -EINVAL;
+	}
 
 	event = nextEvent(YAML_MAPPING_START_EVENT);
 	if (!event)

src/cam/capture_script.h

@@ -40,6 +40,7 @@ private:
 	std::map<unsigned int, libcamera::ControlList> frameControls_;
 	std::shared_ptr<libcamera::Camera> camera_;
 	yaml_parser_t parser_;
+	unsigned int loop_;
 	bool valid_;
 
 	EventPtr nextEvent(yaml_event_type_t expectedType = YAML_NO_EVENT);
@@ -49,6 +50,8 @@ private:
 
 	int parseScript(FILE *script);
 
+	int parseProperties();
+	int parseProperty();
 	int parseFrames();
 	int parseFrame(EventPtr event);
 	int parseControl(EventPtr event, libcamera::ControlList &controls);