codectimestamper: Implement QUERY_CAPS support

This is required to ensure that downstream restrcitions are also
propagated upstream.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4341>

subprojects/gst-plugins-bad/gst/codectimestamper/gstcodectimestamper.c

@@ -76,13 +76,16 @@ static GstFlowReturn gst_codec_timestamper_chain (GstPad * pad,
     GstObject * parent, GstBuffer * buffer);
 static gboolean gst_codec_timestamper_sink_event (GstPad * pad,
     GstObject * parent, GstEvent * event);
+static gboolean gst_codec_timestamper_sink_query (GstPad * pad,
+    GstObject * parent, GstQuery * query);
 static gboolean gst_codec_timestamper_src_query (GstPad * pad,
     GstObject * parent, GstQuery * query);
-static GstStateChangeReturn
-gst_codec_timestamper_change_state (GstElement * element,
-    GstStateChange transition);
-static void
-gst_codec_timestamper_clear_frame (GstCodecTimestamperFrame * frame);
+static GstCaps *gst_timestamper_get_caps (GstCodecTimestamper * self,
+    GstCaps * filter);
+static GstStateChangeReturn gst_codec_timestamper_change_state (GstElement *
+    element, GstStateChange transition);
+static void gst_codec_timestamper_clear_frame (GstCodecTimestamperFrame *
+    frame);
 static void gst_codec_timestamper_reset (GstCodecTimestamper * self);
 static void gst_codec_timestamper_drain (GstCodecTimestamper * self);
 
@@ -142,6 +145,9 @@ gst_codec_timestamper_class_init (GstCodecTimestamperClass * klass)
   element_class->change_state =
       GST_DEBUG_FUNCPTR (gst_codec_timestamper_change_state);
 
+  /* Default implementation is correct for both H264 and H265 */
+  klass->get_sink_caps = gst_timestamper_get_caps;
+
   GST_DEBUG_CATEGORY_INIT (gst_codec_timestamper_debug, "codectimestamper", 0,
       "codectimestamper");
 
@@ -169,6 +175,9 @@ gst_codec_timestamper_init (GstCodecTimestamper * self,
       GST_DEBUG_FUNCPTR (gst_codec_timestamper_chain));
   gst_pad_set_event_function (self->sinkpad,
       GST_DEBUG_FUNCPTR (gst_codec_timestamper_sink_event));
+  gst_pad_set_query_function (self->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_codec_timestamper_sink_query));
+
   GST_PAD_SET_PROXY_SCHEDULING (self->sinkpad);
   GST_PAD_SET_ACCEPT_INTERSECT (self->sinkpad);
   GST_PAD_SET_ACCEPT_TEMPLATE (self->sinkpad);
@@ -582,6 +591,76 @@ gst_codec_timestamper_chain (GstPad * pad, GstObject * parent,
   return gst_codec_timestamper_process_output_frame (self);
 }
 
+static GstCaps *
+gst_timestamper_get_caps (GstCodecTimestamper * self, GstCaps * filter)
+{
+  GstCaps *peercaps, *templ;
+  GstCaps *res, *tmp, *pcopy;
+
+  templ = gst_pad_get_pad_template_caps (self->sinkpad);
+  if (filter) {
+    GstCaps *fcopy = gst_caps_copy (filter);
+
+    peercaps = gst_pad_peer_query_caps (self->srcpad, fcopy);
+    gst_caps_unref (fcopy);
+  } else {
+    peercaps = gst_pad_peer_query_caps (self->srcpad, NULL);
+  }
+
+  pcopy = gst_caps_copy (peercaps);
+
+  res = gst_caps_intersect_full (pcopy, templ, GST_CAPS_INTERSECT_FIRST);
+  gst_caps_unref (pcopy);
+  gst_caps_unref (templ);
+
+  if (filter) {
+    GstCaps *tmp = gst_caps_intersect_full (res, filter,
+        GST_CAPS_INTERSECT_FIRST);
+    gst_caps_unref (res);
+    res = tmp;
+  }
+
+  /* Try if we can put the downstream caps first */
+  pcopy = gst_caps_copy (peercaps);
+  tmp = gst_caps_intersect_full (pcopy, res, GST_CAPS_INTERSECT_FIRST);
+  gst_caps_unref (pcopy);
+  if (!gst_caps_is_empty (tmp))
+    res = gst_caps_merge (tmp, res);
+  else
+    gst_caps_unref (tmp);
+
+  gst_caps_unref (peercaps);
+  return res;
+}
+
+static gboolean
+gst_codec_timestamper_sink_query (GstPad * pad, GstObject * parent,
+    GstQuery * query)
+{
+  GstCodecTimestamper *self = GST_CODEC_TIMESTAMPER (parent);
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_CAPS:{
+      GstCaps *caps, *filter;
+      GstCodecTimestamperClass *klass = GST_CODEC_TIMESTAMPER_GET_CLASS (self);
+
+      gst_query_parse_caps (query, &filter);
+      g_assert (klass->get_sink_caps);
+      caps = klass->get_sink_caps (self, filter);
+      GST_LOG_OBJECT (self, "sink getcaps returning caps %" GST_PTR_FORMAT,
+          caps);
+      gst_query_set_caps_result (query, caps);
+      gst_caps_unref (caps);
+
+      return TRUE;
+    }
+    default:
+      break;
+  }
+
+  return gst_pad_query_default (pad, parent, query);
+}
+
 static gboolean
 gst_codec_timestamper_src_query (GstPad * pad, GstObject * parent,
     GstQuery * query)

subprojects/gst-plugins-bad/gst/codectimestamper/gstcodectimestamper.h

@@ -54,6 +54,9 @@ struct _GstCodecTimestamperClass
   gboolean      (*set_caps)      (GstCodecTimestamper * timestamper,
                                   GstCaps * caps);
 
+  GstCaps *     (*get_sink_caps) (GstCodecTimestamper * timestamper,
+                                  GstCaps      * filter);
+
   GstFlowReturn (*handle_buffer) (GstCodecTimestamper * timestamper,
                                   GstBuffer * buffer);
 };

subprojects/gst-plugins-bad/tests/validate/codectimestamper/h264_propagate_caps.validatetest

@@ -0,0 +1,9 @@
+meta,
+    args = {
+        "videotestsrc num-buffers=1 ! video/x-raw,width=1920,height=1080,format=I420 ! videoscale  ! x264enc tune=zerolatency ! h264timestamper ! video/x-h264,width=50,height=50 ! fakesink name=sink",
+    },
+    configs = {
+        "$(validateflow), pad=sink:sink, buffers-checksum=as-id, caps-properties={width, height}, ignored-event-types={tag}",
+    }
+
+

subprojects/gst-plugins-bad/tests/validate/codectimestamper/h264_propagate_caps/flow-expectations/log-sink-sink-expected

@@ -0,0 +1,5 @@
+event stream-start: GstEventStreamStart, flags=(GstStreamFlags)GST_STREAM_FLAG_NONE, group-id=(uint)1;
+event caps: video/x-h264, height=(int)50, width=(int)50;
+event segment: format=TIME, start=1000:00:00.000000000, offset=0:00:00.000000000, stop=none, time=0:00:00.000000000, base=0:00:00.000000000, position=1000:00:00.000000000
+buffer: content-id=0, dts=1000:00:00.000000000, pts=1000:00:00.000000000, dur=0:00:00.033333333, flags=discont marker
+event eos: (no structure)

subprojects/gst-plugins-bad/tests/validate/meson.build

@@ -6,6 +6,7 @@ endif
 tests = [
     {'path': 'opencv/cvtracker'},
     {'path': 'testsrcbin/caps_spec'},
+    {'path': 'codectimestamper/h264_propagate_caps'},
     {'path': 'wpe/load_bytes_first', 'skip': not building_wpe},
 ]