[libcamera-devel] [PATCH 05/13] gstreamer: Move timestamp calculation out of pad loop

[Laurent Pinchart]

The buffer pts and the pad latency are computed from the framebuffer
timestamp, separately for each pad. Use the sensor timestamp provided
through the request metadata instead, to compute the values once outside
of the pads loop.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/gstreamer/gstlibcamerasrc.cpp | 34 ++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
index 700bee2bf877..a1fab71d4f09 100644
--- a/src/gstreamer/gstlibcamerasrc.cpp
+++ b/src/gstreamer/gstlibcamerasrc.cpp
@@ -34,6 +34,7 @@
 
 #include <libcamera/camera.h>
 #include <libcamera/camera_manager.h>
+#include <libcamera/control_ids.h>
 
 #include <gst/base/base.h>
 
@@ -164,22 +165,35 @@ GstLibcameraSrcState::requestCompleted(Request *request)
 		return;
 	}
 
+	GstClockTime latency;
+	GstClockTime pts;
+
+	if (GST_ELEMENT_CLOCK(src_)) {
+		int64_t timestamp = request->metadata().get(controls::SensorTimestamp);
+
+		GstClockTime gst_base_time = GST_ELEMENT(src_)->base_time;
+		GstClockTime gst_now = gst_clock_get_time(GST_ELEMENT_CLOCK(src_));
+		/* \todo Need to expose which reference clock the timestamp relates to. */
+		GstClockTime sys_now = g_get_monotonic_time() * 1000;
+
+		/* Deduced from: sys_now - sys_base_time == gst_now - gst_base_time */
+		GstClockTime sys_base_time = sys_now - (gst_now - gst_base_time);
+		pts = timestamp - sys_base_time;
+		latency = sys_now - timestamp;
+	} else {
+		latency = 0;
+		pts = 0;
+	}
+
 	for (GstPad *srcpad : srcpads_) {
 		Stream *stream = gst_libcamera_pad_get_stream(srcpad);
 		GstBuffer *buffer = wrap->detachBuffer(stream);
 
 		FrameBuffer *fb = gst_libcamera_buffer_get_frame_buffer(buffer);
 
-		if (GST_ELEMENT_CLOCK(src_)) {
-			GstClockTime gst_base_time = GST_ELEMENT(src_)->base_time;
-			GstClockTime gst_now = gst_clock_get_time(GST_ELEMENT_CLOCK(src_));
-			/* \todo Need to expose which reference clock the timestamp relates to. */
-			GstClockTime sys_now = g_get_monotonic_time() * 1000;
-
-			/* Deduced from: sys_now - sys_base_time == gst_now - gst_base_time */
-			GstClockTime sys_base_time = sys_now - (gst_now - gst_base_time);
-			GST_BUFFER_PTS(buffer) = fb->metadata().timestamp - sys_base_time;
-			gst_libcamera_pad_set_latency(srcpad, sys_now - fb->metadata().timestamp);
+		if (pts) {
+			GST_BUFFER_PTS(buffer) = pts;
+			gst_libcamera_pad_set_latency(srcpad, latency);
 		} else {
 			GST_BUFFER_PTS(buffer) = 0;
 		}
-- 
Regards,

Laurent Pinchart