From 54cc985810f6a8faf88fe5c26f6af8dc194280b0 Mon Sep 17 00:00:00 2001
From: Mathieu Duponchelle <mathieu@centricular.com>
Date: Thu, 30 Jan 2020 19:00:07 +0100
Subject: [PATCH] videoaggregator: handle gap buffers properly

This simply implies not trying to "prepare" those buffers,
as mapping an empty buffer to a video frame does not make
much sense.

This also adds a simple test in compositor that performs
some trivial checking of the handling of gap events, the test
was not failing before, but an error was logged, this is
no longer the case.

Fixes #717
---
 gst-libs/gst/video/gstvideoaggregator.c |  7 ++++
 tests/check/elements/compositor.c       | 47 +++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/gst-libs/gst/video/gstvideoaggregator.c b/gst-libs/gst/video/gstvideoaggregator.c
index 2d487f1fb7..b62b62e662 100644
--- a/gst-libs/gst/video/gstvideoaggregator.c
+++ b/gst-libs/gst/video/gstvideoaggregator.c
@@ -1622,6 +1622,13 @@ prepare_frames (GstElement * agg, GstPad * pad, gpointer user_data)
   if (vpad->priv->buffer == NULL || !vaggpad_class->prepare_frame)
     return TRUE;
 
+  /* GAP event, nothing to do */
+  if (vpad->priv->buffer &&
+      gst_buffer_get_size (vpad->priv->buffer) == 0 &&
+      GST_BUFFER_FLAG_IS_SET (vpad->priv->buffer, GST_BUFFER_FLAG_GAP)) {
+    return TRUE;
+  }
+
   return vaggpad_class->prepare_frame (vpad, GST_VIDEO_AGGREGATOR_CAST (agg),
       vpad->priv->buffer, &vpad->priv->prepared_frame);
 }
diff --git a/tests/check/elements/compositor.c b/tests/check/elements/compositor.c
index 8a9db397c5..a1cec01329 100644
--- a/tests/check/elements/compositor.c
+++ b/tests/check/elements/compositor.c
@@ -31,6 +31,7 @@
 
 #include <gst/check/gstcheck.h>
 #include <gst/check/gstconsistencychecker.h>
+#include <gst/check/gstharness.h>
 #include <gst/video/gstvideometa.h>
 #include <gst/base/gstbasesrc.h>
 
@@ -2120,6 +2121,51 @@ GST_START_TEST (test_start_time_first_live_drop_3_unlinked_1)
 
 GST_END_TEST;
 
+GST_START_TEST (test_gap_events)
+{
+  GstBuffer *buf;
+  GstElement *comp = gst_element_factory_make ("compositor", NULL);
+  GstHarness *h = gst_harness_new_with_element (comp, "sink_%u", "src");
+  GstMapInfo info;
+
+  g_object_set (comp, "background", 1, NULL);
+
+  gst_harness_set_src_caps_str (h,
+      "video/x-raw, format=RGBA, width=1, height=1, framerate=25/1");
+
+  gst_harness_play (h);
+
+  gst_harness_push_event (h, gst_event_new_gap (0, 40 * GST_MSECOND));
+
+  buf = gst_buffer_new_allocate (NULL, 4, NULL);
+
+  gst_buffer_map (buf, &info, GST_MAP_WRITE);
+  memset (info.data, 42, info.size);
+  info.data[3] = 255;
+  gst_buffer_unmap (buf, &info);
+
+  GST_BUFFER_PTS (buf) = 40 * GST_MSECOND;
+  GST_BUFFER_DURATION (buf) = 40 * GST_MSECOND;
+  gst_harness_push (h, buf);
+
+  buf = gst_harness_pull (h);
+  gst_buffer_map (buf, &info, GST_MAP_READ);
+  fail_unless (info.data[0] == 0);
+  gst_buffer_unmap (buf, &info);
+  gst_buffer_unref (buf);
+
+  buf = gst_harness_pull (h);
+  gst_buffer_map (buf, &info, GST_MAP_READ);
+  fail_unless (info.data[0] == 42);
+  gst_buffer_unmap (buf, &info);
+  gst_buffer_unref (buf);
+
+  gst_harness_teardown (h);
+  gst_object_unref (comp);
+}
+
+GST_END_TEST;
+
 static Suite *
 compositor_suite (void)
 {
@@ -2158,6 +2204,7 @@ compositor_suite (void)
   tcase_add_test (tc_chain, test_start_time_first_live_drop_0);
   tcase_add_test (tc_chain, test_start_time_first_live_drop_3);
   tcase_add_test (tc_chain, test_start_time_first_live_drop_3_unlinked_1);
+  tcase_add_test (tc_chain, test_gap_events);
 
   return s;
 }