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gst: libcamerasrc: Implement timestamp support

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This is an experimental patch adding timestamp support to the libcamerasrc
element. This patch currently assume that the driver timestamp are relative to
the system monotonic clock. Without a reference clock source, the timestamp are
otherwise unusable, and without timestamp only minor use case can be achieved.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
This commit is contained in:
Nicolas Dufresne
2020-01-28 17:16:17 -05:00
committed by Laurent Pinchart
parent d1d1348228
commit 0c4147c3b6
3 changed files with 45 additions and 0 deletions
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src/gstreamer/gstlibcamerasrc.cpp
+20
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@@ -154,6 +154,26 @@ GstLibcameraSrcState::requestCompleted(Request *request)
for (GstPad *srcpad : srcpads_) {
Stream *stream = gst_libcamera_pad_get_stream(srcpad);
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);
} else {
GST_BUFFER_PTS(buffer) = 0;
}
GST_BUFFER_OFFSET(buffer) = fb->metadata().sequence;
GST_BUFFER_OFFSET_END(buffer) = fb->metadata().sequence;
gst_libcamera_pad_queue_buffer(srcpad, buffer);
}