v4l2: add ALLOCATION query to the sink

diff --git a/sys/v4l2/gstv4l2sink.c b/sys/v4l2/gstv4l2sink.c
index 1ec96bd..14a0f31 100644 (file)
--- a/sys/v4l2/gstv4l2sink.c
+++ b/sys/v4l2/gstv4l2sink.c
@@ -53,6 +53,7 @@
 #include <config.h>
 #endif
 
+#include "gst/video/gstmetavideo.h"
 
 #include "gstv4l2colorbalance.h"
 #include "gstv4l2tuner.h"
@@ -133,11 +134,12 @@ static void gst_v4l2sink_set_property (GObject * object, guint prop_id,
 static void gst_v4l2sink_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec);
 
-
 /* GstElement methods: */
 static GstStateChangeReturn gst_v4l2sink_change_state (GstElement * element,
     GstStateChange transition);
 
+static gboolean gst_v4l2sink_sink_query (GstPad * sinkpad, GstQuery * query);
+
 /* GstBaseSink methods: */
 static GstCaps *gst_v4l2sink_get_caps (GstBaseSink * bsink, GstCaps * filter);
 static gboolean gst_v4l2sink_set_caps (GstBaseSink * bsink, GstCaps * caps);
@@ -234,6 +236,10 @@ gst_v4l2sink_class_init (GstV4l2SinkClass * klass)
 static void
 gst_v4l2sink_init (GstV4l2Sink * v4l2sink)
 {
+  /* for the ALLOCATION query */
+  gst_pad_set_query_function (GST_BASE_SINK (v4l2sink)->sinkpad,
+      gst_v4l2sink_sink_query);
+
   v4l2sink->v4l2object = gst_v4l2_object_new (GST_ELEMENT (v4l2sink),
       V4L2_BUF_TYPE_VIDEO_OUTPUT, DEFAULT_PROP_DEVICE,
       gst_v4l2_get_output, gst_v4l2_set_output, NULL);
@@ -662,6 +668,75 @@ invalid_format:
   }
 }
 
+static gboolean
+gst_v4l2sink_sink_query (GstPad * sinkpad, GstQuery * query)
+{
+  GstV4l2Sink *v4l2sink = GST_V4L2SINK (GST_PAD_PARENT (sinkpad));
+  GstV4l2Object *obj = v4l2sink->v4l2object;
+  gboolean res = TRUE;
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_ALLOCATION:
+    {
+      GstBufferPool *pool;
+      GstStructure *config;
+      GstCaps *caps;
+      guint size = 0;
+      gboolean need_pool;
+
+      gst_query_parse_allocation (query, &caps, &need_pool);
+
+      if (caps == NULL)
+        goto no_caps;
+
+      if ((pool = obj->pool))
+        gst_object_ref (pool);
+
+      if (pool != NULL) {
+        const GstCaps *pcaps;
+
+        /* we had a pool, check caps */
+        config = gst_buffer_pool_get_config (pool);
+        gst_buffer_pool_config_get (config, &pcaps, &size, NULL, NULL, NULL,
+            NULL);
+
+        GST_DEBUG_OBJECT (v4l2sink,
+            "we had a pool with caps %" GST_PTR_FORMAT, pcaps);
+        if (!gst_caps_is_equal (caps, pcaps)) {
+          gst_object_unref (pool);
+          goto different_caps;
+        }
+      }
+      gst_query_set_allocation_params (query, size, 0, 0, 0, 15, pool);
+
+      /* we also support various metadata */
+      gst_query_add_allocation_meta (query, GST_META_API_VIDEO);
+      gst_query_add_allocation_meta (query, GST_META_API_VIDEO_CROP);
+
+      if (pool)
+        gst_object_unref (pool);
+      break;
+    }
+    default:
+      res = FALSE;
+      break;
+  }
+  return res;
+
+  /* ERRORS */
+no_caps:
+  {
+    GST_DEBUG_OBJECT (sinkpad, "no caps specified");
+    return FALSE;
+  }
+different_caps:
+  {
+    /* different caps, we can't use this pool */
+    GST_DEBUG_OBJECT (v4l2sink, "pool has different caps");
+    return FALSE;
+  }
+}
+
 /* called after A/V sync to render frame */
 static GstFlowReturn
 gst_v4l2sink_show_frame (GstBaseSink * bsink, GstBuffer * buf)