@@ -469,6 +469,32 @@ and the bytes used by planes.
seq: 000040 bytesused: 1843200
seq: 000042 bytesused: 1843200
+Request metadata
+~~~~~~~~~~~~~~~~
+
+Completed requests also expose metadata as a :doxy-pub:`ControlList` through
+:doxy-pub:`Request::metadata()`. Pipeline handlers populate this list with
+controls defined as ``direction: out`` in the control definition YAML files.
+
+Common entries include :doxy-pub:`controls::SensorTimestamp`,
+:doxy-pub:`controls::FrameWallClock`, and :doxy-pub:`controls::SensorSequence`.
+The latter reports the sequence number from the sensor-facing capture device
+(for example the CSI-2 receiver or V4L2 video node) for the frame associated
+with the request.
+
+While per-buffer :doxy-pub:`FrameMetadata::sequence` identifies frames in each
+completed stream, ``SensorSequence`` reflects the sensor-side capture path. If
+the value increases by more than one between consecutive completed requests,
+frames were not captured before the earlier request finished. This complements
+sequence numbers derived from request delivery and is intended for diagnosing
+frame continuity.
+
+.. code:: cpp
+
+ const ControlList &metadata = request->metadata();
+ if (auto seq = metadata.get<int64_t>(controls::SensorSequence))
+ std::cout << " sensor sequence: " << *seq << std::endl;
+
A completed buffer contains of course image data which can be accessed through
the per-plane dma-buf file descriptor transported by the ``FrameBuffer``
instance. An example of how to write image data to disk is available in the
Describe how applications read SensorSequence from Request::metadata() and how it differs from per-buffer FrameMetadata::sequence. Signed-off-by: Bruce Allen <ballen4705@googlemail.com> --- Documentation/guides/application-developer.rst | 26 ++++++++++++++++++++++ 1 file changed, 26 insertions(+)