diff -r 000000000000 -r 0e761a78d257 gst_plugins_base/tests/check/elements/textoverlay.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gst_plugins_base/tests/check/elements/textoverlay.c	Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,749 @@
+/* GStreamer unit tests for textoverlay
+ *
+ * Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <unistd.h>
+
+#include <gst/check/gstcheck.h>
+
+#define I420_Y_ROWSTRIDE(width) (GST_ROUND_UP_4(width))
+#define I420_U_ROWSTRIDE(width) (GST_ROUND_UP_8(width)/2)
+#define I420_V_ROWSTRIDE(width) ((GST_ROUND_UP_8(I420_Y_ROWSTRIDE(width)))/2)
+
+#define I420_Y_OFFSET(w,h) (0)
+#define I420_U_OFFSET(w,h) (I420_Y_OFFSET(w,h)+(I420_Y_ROWSTRIDE(w)*GST_ROUND_UP_2(h)))
+#define I420_V_OFFSET(w,h) (I420_U_OFFSET(w,h)+(I420_U_ROWSTRIDE(w)*GST_ROUND_UP_2(h)/2))
+
+#define I420_SIZE(w,h)     (I420_V_OFFSET(w,h)+(I420_V_ROWSTRIDE(w)*GST_ROUND_UP_2(h)/2))
+
+#define WIDTH 240
+#define HEIGHT 120
+
+/* For ease of programming we use globals to keep refs for our floating
+ * src and sink pads we create; otherwise we always have to do get_pad,
+ * get_peer, and then remove references in every test function */
+static GstPad *myvideosrcpad, *mytextsrcpad, *mysinkpad;
+
+#define VIDEO_CAPS_STRING               \
+    "video/x-raw-yuv, "                 \
+    "format = (fourcc) I420, "          \
+    "framerate = (fraction) 1/1, "      \
+    "width = (int) 240, "               \
+    "height = (int) 120"
+
+#define VIDEO_CAPS_TEMPLATE_STRING      \
+    "video/x-raw-yuv, "                 \
+    "format = (fourcc) I420"
+
+static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (VIDEO_CAPS_TEMPLATE_STRING)
+    );
+static GstStaticPadTemplate text_srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("text/plain")
+    );
+
+static GstStaticPadTemplate video_srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (VIDEO_CAPS_TEMPLATE_STRING)
+    );
+
+/* much like gst_check_setup_src_pad(), but with possibility to give a hint
+ * which sink template of the element to use, if there are multiple ones */
+static GstPad *
+notgst_check_setup_src_pad2 (GstElement * element,
+    GstStaticPadTemplate * template, GstCaps * caps,
+    const gchar * sink_template_name)
+{
+  GstPad *srcpad, *sinkpad;
+
+  if (sink_template_name == NULL)
+    sink_template_name = "sink";
+
+  /* sending pad */
+  srcpad = gst_pad_new_from_static_template (template, "src");
+  GST_DEBUG_OBJECT (element, "setting up sending pad %p", srcpad);
+  fail_if (srcpad == NULL, "Could not create a srcpad");
+  ASSERT_OBJECT_REFCOUNT (srcpad, "srcpad", 1);
+
+  sinkpad = gst_element_get_pad (element, sink_template_name);
+  fail_if (sinkpad == NULL, "Could not get sink pad from %s",
+      GST_ELEMENT_NAME (element));
+  ASSERT_OBJECT_REFCOUNT (sinkpad, "sinkpad", 2);
+  if (caps)
+    fail_unless (gst_pad_set_caps (srcpad, caps));
+  fail_unless (gst_pad_link (srcpad, sinkpad) == GST_PAD_LINK_OK,
+      "Could not link source and %s sink pads", GST_ELEMENT_NAME (element));
+  gst_object_unref (sinkpad);   /* because we got it higher up */
+  ASSERT_OBJECT_REFCOUNT (sinkpad, "sinkpad", 1);
+
+  return srcpad;
+}
+
+static void
+notgst_check_teardown_src_pad2 (GstElement * element,
+    const gchar * sink_template_name)
+{
+  GstPad *srcpad, *sinkpad;
+
+  if (sink_template_name == NULL)
+    sink_template_name = "sink";
+
+  /* clean up floating src pad */
+  sinkpad = gst_element_get_pad (element, sink_template_name);
+  ASSERT_OBJECT_REFCOUNT (sinkpad, "sinkpad", 2);
+  srcpad = gst_pad_get_peer (sinkpad);
+
+  gst_pad_unlink (srcpad, sinkpad);
+
+  /* caps could have been set, make sure they get unset */
+  gst_pad_set_caps (srcpad, NULL);
+
+  /* pad refs held by both creator and this function (through _get) */
+  ASSERT_OBJECT_REFCOUNT (sinkpad, "element sinkpad", 2);
+  gst_object_unref (sinkpad);
+  /* one more ref is held by element itself */
+
+  /* pad refs held by both creator and this function (through _get_peer) */
+  ASSERT_OBJECT_REFCOUNT (srcpad, "check srcpad", 2);
+  gst_object_unref (srcpad);
+  gst_object_unref (srcpad);
+}
+
+static GstElement *
+setup_textoverlay (gboolean video_only_no_text)
+{
+  GstElement *textoverlay;
+
+  GST_DEBUG ("setup_textoverlay");
+  textoverlay = gst_check_setup_element ("textoverlay");
+  mysinkpad = gst_check_setup_sink_pad (textoverlay, &sinktemplate, NULL);
+  myvideosrcpad =
+      notgst_check_setup_src_pad2 (textoverlay, &video_srctemplate, NULL,
+      "video_sink");
+
+  if (!video_only_no_text) {
+    mytextsrcpad =
+        notgst_check_setup_src_pad2 (textoverlay, &text_srctemplate, NULL,
+        "text_sink");
+    gst_pad_set_active (mytextsrcpad, TRUE);
+  } else {
+    mytextsrcpad = NULL;
+  }
+
+  gst_pad_set_active (myvideosrcpad, TRUE);
+  gst_pad_set_active (mysinkpad, TRUE);
+
+  return textoverlay;
+}
+
+static gboolean
+buffer_is_all_black (GstBuffer * buf)
+{
+  GstStructure *s;
+  gint x, y, w, h;
+
+  fail_unless (buf != NULL);
+  fail_unless (GST_BUFFER_CAPS (buf) != NULL);
+  s = gst_caps_get_structure (GST_BUFFER_CAPS (buf), 0);
+  fail_unless (s != NULL);
+  fail_unless (gst_structure_get_int (s, "width", &w));
+  fail_unless (gst_structure_get_int (s, "height", &h));
+
+  for (y = 0; y < h; ++y) {
+    guint8 *data = GST_BUFFER_DATA (buf) + (y * GST_ROUND_UP_4 (w));
+
+    for (x = 0; x < w; ++x) {
+      if (data[x] != 0x00) {
+        GST_LOG ("non-black pixel at (x,y) %d,%d", x, y);
+        return FALSE;
+      }
+    }
+  }
+
+  return TRUE;
+}
+
+static GstBuffer *
+create_black_buffer (const gchar * caps_string)
+{
+  GstStructure *s;
+  GstBuffer *buffer;
+  GstCaps *caps;
+  gint w, h, size;
+
+  fail_unless (caps_string != NULL);
+
+  caps = gst_caps_from_string (caps_string);
+  fail_unless (caps != NULL);
+  fail_unless (gst_caps_is_fixed (caps));
+
+  s = gst_caps_get_structure (caps, 0);
+  fail_unless (gst_structure_get_int (s, "width", &w));
+  fail_unless (gst_structure_get_int (s, "height", &h));
+
+  GST_LOG ("creating buffer (%dx%d)", w, h);
+  size = I420_SIZE (w, h);
+  buffer = gst_buffer_new_and_alloc (size);
+  /* we're only checking the Y plane later, so just zero it all out,
+   * even if it's not the blackest black there is */
+  memset (GST_BUFFER_DATA (buffer), 0, size);
+
+  gst_buffer_set_caps (buffer, caps);
+  gst_caps_unref (caps);
+
+  /* double check to make sure it's been created right */
+  fail_unless (buffer_is_all_black (buffer));
+
+  return buffer;
+}
+
+static GstBuffer *
+create_text_buffer (const gchar * txt, GstClockTime ts, GstClockTime duration)
+{
+  GstBuffer *buffer;
+  GstCaps *caps;
+  guint txt_len;
+
+  fail_unless (txt != NULL);
+
+  txt_len = strlen (txt);
+
+  buffer = gst_buffer_new_and_alloc (txt_len);
+  memcpy (GST_BUFFER_DATA (buffer), txt, txt_len);
+
+  GST_BUFFER_TIMESTAMP (buffer) = ts;
+  GST_BUFFER_DURATION (buffer) = duration;
+
+  caps = gst_caps_new_simple ("text/plain", NULL);
+  gst_buffer_set_caps (buffer, caps);
+  gst_caps_unref (caps);
+
+  return buffer;
+}
+
+static void
+cleanup_textoverlay (GstElement * textoverlay)
+{
+  GST_DEBUG ("cleanup_textoverlay");
+
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+
+  gst_element_set_state (textoverlay, GST_STATE_NULL);
+  gst_element_get_state (textoverlay, NULL, NULL, GST_CLOCK_TIME_NONE);
+  gst_pad_set_active (myvideosrcpad, FALSE);
+  gst_pad_set_active (mysinkpad, FALSE);
+  notgst_check_teardown_src_pad2 (textoverlay, "video_sink");
+  if (mytextsrcpad) {
+    notgst_check_teardown_src_pad2 (textoverlay, "text_sink");
+  }
+  gst_check_teardown_sink_pad (textoverlay);
+  gst_check_teardown_element (textoverlay);
+}
+
+GST_START_TEST (test_video_passthrough)
+{
+  GstElement *textoverlay;
+  GstBuffer *inbuffer;
+
+  textoverlay = setup_textoverlay (TRUE);
+  fail_unless (gst_element_set_state (textoverlay,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_SUCCESS,
+      "could not set to playing");
+
+  inbuffer = create_black_buffer (VIDEO_CAPS_STRING);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* ========== (1) video buffer without timestamp => should be dropped ==== */
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* should have been discarded as out-of-segment since it has no timestamp */
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+  fail_unless_equals_int (g_list_length (buffers), 0);
+
+  /* ========== (2) buffer with 0 timestamp => simple passthrough ========== */
+
+  /* now try again, this time with timestamp (segment defaults to 0 start) */
+  GST_BUFFER_TIMESTAMP (inbuffer) = 0;
+  GST_BUFFER_DURATION (inbuffer) = GST_CLOCK_TIME_NONE;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* text pad is not linked, timestamp is in segment, no static text to
+   * render, should have gone through right away without modification */
+  fail_unless_equals_int (g_list_length (buffers), 1);
+  fail_unless (GST_BUFFER_CAST (buffers->data) == inbuffer);
+  fail_unless (buffer_is_all_black (inbuffer));
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* and clean up */
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* ========== (3) buffer with 0 timestamp and no duration, with the
+   *                segment starting from 1sec => should be discarded */
+
+  gst_pad_push_event (myvideosrcpad,
+      gst_event_new_new_segment (FALSE, 1.0, GST_FORMAT_TIME, 1 * GST_SECOND,
+          -1, 0));
+
+  GST_BUFFER_TIMESTAMP (inbuffer) = 0;
+  GST_BUFFER_DURATION (inbuffer) = GST_CLOCK_TIME_NONE;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* should have been discarded as out-of-segment */
+  fail_unless_equals_int (g_list_length (buffers), 0);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* ========== (4) buffer with 0 timestamp and small defined duration, with
+   *                segment starting from 1sec => should be discarded */
+
+  gst_pad_push_event (myvideosrcpad,
+      gst_event_new_new_segment (FALSE, 1.0, 1 * GST_FORMAT_TIME, GST_SECOND,
+          -1, 0));
+
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND / 10;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* should have been discareded as out-of-segment since it has no timestamp */
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+  fail_unless_equals_int (g_list_length (buffers), 0);
+
+  /* ========== (5) buffer partially overlapping into the segment => should
+   *                be pushed through, but with adjusted stamp values */
+
+  gst_pad_push_event (myvideosrcpad,
+      gst_event_new_new_segment (FALSE, 1.0, 1 * GST_FORMAT_TIME, GST_SECOND,
+          -1, 0));
+
+  GST_BUFFER_TIMESTAMP (inbuffer) = GST_SECOND / 4;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* should be the parent for a new subbuffer for the stamp fix-up */
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+  fail_unless_equals_int (g_list_length (buffers), 1);
+  fail_unless (GST_BUFFER_CAST (buffers->data) != inbuffer);
+  fail_unless (GST_BUFFER_TIMESTAMP (GST_BUFFER_CAST (buffers->data)) ==
+      GST_SECOND);
+  fail_unless (GST_BUFFER_DURATION (GST_BUFFER_CAST (buffers->data)) ==
+      (GST_SECOND / 4));
+  fail_unless (buffer_is_all_black (GST_BUFFER_CAST (buffers->data)));
+  /* and clean up */
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* cleanup */
+  cleanup_textoverlay (textoverlay);
+  gst_buffer_unref (inbuffer);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (test_video_render_static_text)
+{
+  GstElement *textoverlay;
+  GstBuffer *inbuffer;
+
+  textoverlay = setup_textoverlay (TRUE);
+
+  /* set static text to render */
+  g_object_set (textoverlay, "text", "XLX", NULL);
+
+  fail_unless (gst_element_set_state (textoverlay,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_SUCCESS,
+      "could not set to playing");
+
+  inbuffer = create_black_buffer (VIDEO_CAPS_STRING);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  GST_BUFFER_TIMESTAMP (inbuffer) = 0;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND / 10;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* should have been dropped in favour of a new writable buffer */
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+  fail_unless_equals_int (g_list_length (buffers), 1);
+  fail_unless (GST_BUFFER_CAST (buffers->data) != inbuffer);
+
+  /* there should be text rendered */
+  fail_unless (buffer_is_all_black (GST_BUFFER_CAST (buffers->data)) == FALSE);
+
+  fail_unless (GST_BUFFER_TIMESTAMP (GST_BUFFER_CAST (buffers->data)) == 0);
+  fail_unless (GST_BUFFER_DURATION (GST_BUFFER_CAST (buffers->data)) ==
+      (GST_SECOND / 10));
+
+  /* and clean up */
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* cleanup */
+  cleanup_textoverlay (textoverlay);
+  gst_buffer_unref (inbuffer);
+}
+
+GST_END_TEST;
+
+static gpointer
+test_video_waits_for_text_send_text_newsegment_thread (gpointer data)
+{
+  g_usleep (1 * G_USEC_PER_SEC);
+
+  /* send an update newsegment; the video buffer should now be pushed through 
+   * even though there is no text buffer queued at the moment */
+  GST_INFO ("Sending newsegment update on text pad");
+  gst_pad_push_event (mytextsrcpad,
+      gst_event_new_new_segment (TRUE, 1.0, GST_FORMAT_TIME,
+          35 * GST_SECOND, -1, 35 * GST_SECOND));
+
+  return NULL;
+}
+
+static gpointer
+test_video_waits_for_text_shutdown_element (gpointer data)
+{
+  g_usleep (1 * G_USEC_PER_SEC);
+
+  GST_INFO ("Trying to shut down textoverlay element ...");
+  /* set to NULL state to make sure we can shut it down while it's
+   * blocking in the video chain function waiting for a text buffer */
+  gst_element_set_state (GST_ELEMENT (data), GST_STATE_NULL);
+  GST_INFO ("Done.");
+
+  return NULL;
+}
+
+GST_START_TEST (test_video_waits_for_text)
+{
+  GstElement *textoverlay;
+  GstBuffer *inbuffer, *tbuf;
+  GThread *thread;
+
+  textoverlay = setup_textoverlay (FALSE);
+
+  fail_unless (gst_element_set_state (textoverlay,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_SUCCESS,
+      "could not set to playing");
+
+  tbuf = create_text_buffer ("XLX", 1 * GST_SECOND, 5 * GST_SECOND);
+  gst_buffer_ref (tbuf);
+  ASSERT_BUFFER_REFCOUNT (tbuf, "tbuf", 2);
+
+  GST_LOG ("pushing text buffer");
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  /* it should be stuck in textoverlay until it gets a text buffer or a
+   * newsegment event that indicates it's not needed any longer */
+  fail_unless_equals_int (g_list_length (buffers), 0);
+
+  inbuffer = create_black_buffer (VIDEO_CAPS_STRING);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  GST_BUFFER_TIMESTAMP (inbuffer) = 0;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND / 2;
+
+  /* take additional ref to keep it alive */
+  gst_buffer_ref (inbuffer);
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 2);
+
+  /* pushing gives away one of the two references we have ... */
+  GST_LOG ("pushing video buffer 1");
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* video buffer should have gone through untainted, since the text is later */
+  fail_unless_equals_int (g_list_length (buffers), 1);
+
+  /* text should still be stuck in textoverlay */
+  ASSERT_BUFFER_REFCOUNT (tbuf, "tbuf", 2);
+
+  /* there should be no text rendered */
+  fail_unless (buffer_is_all_black (GST_BUFFER_CAST (buffers->data)));
+
+  /* now, another video buffer */
+  inbuffer = gst_buffer_make_metadata_writable (inbuffer);
+  GST_BUFFER_TIMESTAMP (inbuffer) = GST_SECOND;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND / 2;
+
+  /* pushing gives away one of the two references we have ... */
+  GST_LOG ("pushing video buffer 2");
+  gst_buffer_ref (inbuffer);
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* video buffer should have gone right away, with text rendered on it */
+  fail_unless_equals_int (g_list_length (buffers), 2);
+
+  /* text should still be stuck in textoverlay */
+  ASSERT_BUFFER_REFCOUNT (tbuf, "tbuf", 2);
+
+  /* there should be text rendered */
+  fail_unless (buffer_is_all_black (GST_BUFFER_CAST (buffers->next->data)) ==
+      FALSE);
+
+  /* a third video buffer */
+  inbuffer = gst_buffer_make_metadata_writable (inbuffer);
+  GST_BUFFER_TIMESTAMP (inbuffer) = 30 * GST_SECOND;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND / 2;
+
+  /* video buffer #3: should not go through, it should discard the current
+   * text buffer as too old and then wait for the next text buffer (or a
+   * newsegment event to arrive); we spawn a background thread to send such
+   * a newsegment event after a second or so so we get back control */
+  thread =
+      g_thread_create (test_video_waits_for_text_send_text_newsegment_thread,
+      NULL, FALSE, NULL);
+  fail_unless (thread != NULL);
+
+  GST_LOG ("pushing video buffer 3");
+  gst_buffer_ref (inbuffer);
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_OK);
+
+  /* but the text should no longer be stuck in textoverlay */
+  ASSERT_BUFFER_REFCOUNT (tbuf, "tbuf", 1);
+
+  /* video buffer should have gone through after newsegment event */
+  fail_unless_equals_int (g_list_length (buffers), 3);
+
+  /* ... and there should not be any text rendered on it */
+  fail_unless (buffer_is_all_black (GST_BUFFER_CAST (buffers->next->next->
+              data)));
+
+  /* a fourth video buffer */
+  inbuffer = gst_buffer_make_metadata_writable (inbuffer);
+  GST_BUFFER_TIMESTAMP (inbuffer) = 35 * GST_SECOND;
+  GST_BUFFER_DURATION (inbuffer) = GST_SECOND;
+
+  /* video buffer #4: should not go through, it should wait for the next
+   * text buffer (or a newsegment event) to arrive; we spawn a background
+   * thread to shut down the element while it's waiting to make sure that
+   * works ok */
+  thread = g_thread_create (test_video_waits_for_text_shutdown_element,
+      textoverlay, FALSE, NULL);
+  fail_unless (thread != NULL);
+
+  GST_LOG ("pushing video buffer 4");
+  gst_buffer_ref (inbuffer);
+  fail_unless (gst_pad_push (myvideosrcpad, inbuffer) == GST_FLOW_WRONG_STATE);
+
+  /* and clean up */
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+  ASSERT_BUFFER_REFCOUNT (inbuffer, "inbuffer", 1);
+
+  /* cleanup */
+  cleanup_textoverlay (textoverlay);
+  gst_buffer_unref (inbuffer);
+
+  /* give up our ref, textoverlay should've cleared its queued buffer by now */
+  ASSERT_BUFFER_REFCOUNT (tbuf, "tbuf", 1);
+  gst_buffer_unref (tbuf);
+}
+
+GST_END_TEST;
+
+static gpointer
+test_render_continuity_push_video_buffers_thread (gpointer data)
+{
+  /* push video buffers at 1fps */
+  guint frame_count = 0;
+
+  do {
+    GstBuffer *vbuf;
+
+    vbuf = create_black_buffer (VIDEO_CAPS_STRING);
+    ASSERT_BUFFER_REFCOUNT (vbuf, "vbuf", 1);
+
+    GST_BUFFER_TIMESTAMP (vbuf) = frame_count * GST_SECOND;
+    GST_BUFFER_DURATION (vbuf) = GST_SECOND;
+
+    /* pushing gives away one of the two references we have ... */
+    GST_LOG ("pushing video buffer %u @ %" GST_TIME_FORMAT, frame_count,
+        GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (vbuf)));
+    fail_unless (gst_pad_push (myvideosrcpad, vbuf) == GST_FLOW_OK);
+
+    ++frame_count;
+  } while (frame_count < 15);
+
+  return NULL;
+}
+
+
+GST_START_TEST (test_render_continuity)
+{
+  GThread *thread;
+  GstElement *textoverlay;
+  GstBuffer *tbuf;
+
+  textoverlay = setup_textoverlay (FALSE);
+
+  fail_unless (gst_element_set_state (textoverlay,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_SUCCESS,
+      "could not set to playing");
+
+  thread = g_thread_create (test_render_continuity_push_video_buffers_thread,
+      NULL, FALSE, NULL);
+  fail_unless (thread != NULL);
+
+  tbuf = create_text_buffer ("XLX", 2 * GST_SECOND, GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  tbuf = create_text_buffer ("XLX", 3 * GST_SECOND, 2 * GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  tbuf = create_text_buffer ("XLX", 7 * GST_SECOND, GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  tbuf = create_text_buffer ("XLX", 8 * GST_SECOND, GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  tbuf = create_text_buffer ("XLX", 9 * GST_SECOND, GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  tbuf = create_text_buffer ("XLX", 10 * GST_SECOND, 30 * GST_SECOND);
+  GST_LOG ("pushing text buffer @ %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (tbuf)));
+  fail_unless (gst_pad_push (mytextsrcpad, tbuf) == GST_FLOW_OK);
+
+  GST_LOG ("give the other thread some time to push through the remaining"
+      "video buffers");
+  g_usleep (G_USEC_PER_SEC);
+  GST_LOG ("done");
+
+  /* we should have 15 buffers each with one second length now */
+  fail_unless_equals_int (g_list_length (buffers), 15);
+
+  /* buffers 0 + 1 should be black */
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers, 0))));
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers, 1))));
+
+  /* buffers 2 - 4 should have text */
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  2))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  3))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  4))) == FALSE);
+
+  /* buffers 5 + 6 should be black */
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers, 5))));
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers, 6))));
+
+  /* buffers 7 - last should have text */
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  7))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  8))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  9))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  10))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  11))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  12))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  13))) == FALSE);
+  fail_unless (buffer_is_all_black (GST_BUFFER (g_list_nth_data (buffers,
+                  14))) == FALSE);
+
+  /* and clean up */
+  g_list_foreach (buffers, (GFunc) gst_mini_object_unref, NULL);
+  g_list_free (buffers);
+  buffers = NULL;
+
+  /* cleanup */
+  cleanup_textoverlay (textoverlay);
+}
+
+GST_END_TEST;
+
+static Suite *
+textoverlay_suite (void)
+{
+  Suite *s = suite_create ("textoverlay");
+  TCase *tc_chain = tcase_create ("general");
+
+  suite_add_tcase (s, tc_chain);
+
+  tcase_add_test (tc_chain, test_video_passthrough);
+  tcase_add_test (tc_chain, test_video_render_static_text);
+  tcase_add_test (tc_chain, test_render_continuity);
+  tcase_add_test (tc_chain, test_video_waits_for_text);
+
+  return s;
+}
+
+GST_CHECK_MAIN (textoverlay);