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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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23
src/gstreamer/gstlibcamerapad.cpp
View file

@ -63,9 +63,24 @@ gst_libcamera_pad_get_property(GObject *object, guint prop_id, GValue *value,
}
}
static gboolean
gst_libcamera_pad_query(GstPad *pad, GstObject *parent, GstQuery *query)
{
auto *self = GST_LIBCAMERA_PAD(pad);
if (query->type != GST_QUERY_LATENCY)
return gst_pad_query_default(pad, parent, query);
/* TRUE here means live, we assumes that max latency is the same as min
* as we have no idea that duration of frames. */
gst_query_set_latency(query, TRUE, self->latency, self->latency);
return TRUE;
}
static void
gst_libcamera_pad_init(GstLibcameraPad *self)
{
GST_PAD_QUERYFUNC(self) = gst_libcamera_pad_query;
}
static GType
@ -173,3 +188,11 @@ gst_libcamera_pad_has_pending(GstPad *pad)
GLibLocker lock(GST_OBJECT(self));
return self->pending_buffers.length > 0;
}
void
gst_libcamera_pad_set_latency(GstPad *pad, GstClockTime latency)
{
auto *self = GST_LIBCAMERA_PAD(pad);
GLibLocker lock(GST_OBJECT(self));
self->latency = latency;
}

2
src/gstreamer/gstlibcamerapad.h
View file

@ -32,4 +32,6 @@ GstFlowReturn gst_libcamera_pad_push_pending(GstPad *pad);
bool gst_libcamera_pad_has_pending(GstPad *pad);
void gst_libcamera_pad_set_latency(GstPad *pad, GstClockTime latency);
#endif /* __GST_LIBCAMERA_PAD_H__ */

20
src/gstreamer/gstlibcamerasrc.cpp
View file

@ -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);
}