gstreamer/ext/pango/gsttextoverlay.c

/* GStreamer
 * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
 * Copyright (C) <2003> David Schleef <ds@schleef.org>
 *
 * 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.
 */

/**
 * SECTION:element-textoverlay
 * @see_also: #GstTextRender, #GstClockOverlay, #GstTimeOverlay, #GstSubParse
 *
 * <refsect2>
 * <para>
 * This plugin renders text on top of a video stream. This can be either
 * static text or text from buffers received on the text sink pad, e.g.
 * as produced by the subparse element. If the text sink pad is not linked,
 * the text set via the "text" property will be rendered. If the text sink
 * pad is linked, text will be rendered as it is received on that pad,
 * honouring and matching the buffer timestamps of both input streams.
 * </para>
 * <para>
 * The text can contain newline characters and text wrapping is enabled by
 * default.
 * </para>
 * <para>
 * Here is a simple pipeline that displays a static text in the top left
 * corner of the video picture:
 * <programlisting>
 * gst-launch -v videotestsrc ! textoverlay text="Room A" valign=top halign=left ! xvimagesink
 * </programlisting>
 * </para>
 * <para>
 * Here is another pipeline that displays subtitles from an .srt subtitle 
 * file, centered at the bottom of the picture and with a rectangular shading
 * around the text in the background:
 * <programlisting>
 * gst-launch -v filesrc location=subtitles.srt ! subparse ! txt.   videotestsrc ! timeoverlay ! textoverlay name=txt shaded-background=yes ! xvimagesink
 * </programlisting>
 * If you do not have such a subtitle file, create one looking like this
 * in a text editor:
 * <programlisting>
 * 1
 * 00:00:03,000 --> 00:00:05,000
 * Hello? (3-5s)
 * 
 * 2
 * 00:00:08,000 --> 00:00:13,000
 * Yes, this is a subtitle. Don&apos;t
 * you like it? (8-13s)
 * 
 * 3
 * 00:00:18,826 --> 00:01:02,886
 * Uh? What are you talking about?
 * I don&apos;t understand  (18-62s)
 * </programlisting>
 * </para>
 * </refsect2>
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <gst/video/video.h>

#include "gsttextoverlay.h"
#include "gsttimeoverlay.h"
#include "gstclockoverlay.h"
#include "gsttextrender.h"

/* FIXME:
 *  - use proper strides and offset for I420
 *  - if text is wider than the video picture, it does not get
 *    clipped properly during blitting (if wrapping is disabled)
 *  - make 'shading_value' a property (or enum:  light/normal/dark/verydark)?
 */

GST_DEBUG_CATEGORY (pango_debug);
#define GST_CAT_DEFAULT pango_debug

static GstElementDetails text_overlay_details = {
  "Text Overlay",
  "Filter/Editor/Video",
  "Adds text strings on top of a video buffer",
  "David Schleef <ds@schleef.org>"
};

enum
{
  ARG_0,
  ARG_TEXT,
  ARG_SHADING,
  ARG_VALIGN,
  ARG_HALIGN,
  ARG_XPAD,
  ARG_YPAD,
  ARG_DELTAX,
  ARG_DELTAY,
  ARG_WRAP_MODE,
  ARG_FONT_DESC
};


static GstStaticPadTemplate src_template_factory =
GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_YUV ("I420"))
    );

static GstStaticPadTemplate video_sink_template_factory =
GST_STATIC_PAD_TEMPLATE ("video_sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_YUV ("I420"))
    );

static GstStaticPadTemplate text_sink_template_factory =
    GST_STATIC_PAD_TEMPLATE ("text_sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("text/x-pango-markup; text/plain")
    );

/* These macros are adapted from videotestsrc.c */
#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 GST_TEXT_OVERLAY_GET_COND(ov) (((GstTextOverlay *)ov)->cond)
#define GST_TEXT_OVERLAY_WAIT(ov)     (g_cond_wait (GST_TEXT_OVERLAY_GET_COND (ov), GST_OBJECT_GET_LOCK (ov)))
#define GST_TEXT_OVERLAY_SIGNAL(ov)   (g_cond_signal (GST_TEXT_OVERLAY_GET_COND (ov)))
#define GST_TEXT_OVERLAY_BROADCAST(ov)(g_cond_broadcast (GST_TEXT_OVERLAY_GET_COND (ov)))

static GstStateChangeReturn gst_text_overlay_change_state (GstElement * element,
    GstStateChange transition);

static GstCaps *gst_text_overlay_getcaps (GstPad * pad);
static gboolean gst_text_overlay_setcaps (GstPad * pad, GstCaps * caps);
static gboolean gst_text_overlay_src_event (GstPad * pad, GstEvent * event);

static gboolean gst_text_overlay_video_event (GstPad * pad, GstEvent * event);
static GstFlowReturn gst_text_overlay_video_chain (GstPad * pad,
    GstBuffer * buffer);

static gboolean gst_text_overlay_text_event (GstPad * pad, GstEvent * event);
static GstFlowReturn gst_text_overlay_text_chain (GstPad * pad,
    GstBuffer * buffer);
static GstPadLinkReturn gst_text_overlay_text_pad_link (GstPad * pad,
    GstPad * peer);
static void gst_text_overlay_text_pad_unlink (GstPad * pad);
static void gst_text_overlay_pop_text (GstTextOverlay * overlay);

static void gst_text_overlay_finalize (GObject * object);
static void gst_text_overlay_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);


GST_BOILERPLATE (GstTextOverlay, gst_text_overlay, GstElement, GST_TYPE_ELEMENT)
#define DEFAULT_YPAD    25
#define DEFAULT_XPAD    25
#define DEFAULT_DELTAX   0
#define DEFAULT_DELTAY   0
/* keep wrap enum in sync with string in class_init */
#define DEFAULT_WRAP_MODE        GST_TEXT_OVERLAY_WRAP_MODE_WORD_CHAR
#define DEFAULT_SHADING_VALUE    -80
     static void gst_text_overlay_base_init (gpointer g_class)
{
  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&src_template_factory));
  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&video_sink_template_factory));

  /* ugh */
  if (!GST_IS_TIME_OVERLAY_CLASS (g_class) &&
      !GST_IS_CLOCK_OVERLAY_CLASS (g_class)) {
    gst_element_class_add_pad_template (element_class,
        gst_static_pad_template_get (&text_sink_template_factory));
  }

  gst_element_class_set_details (element_class, &text_overlay_details);
}

static gchar *
gst_text_overlay_get_text (GstTextOverlay * overlay, GstBuffer * video_frame)
{
  return g_strdup (overlay->default_text);
}

static void
gst_text_overlay_class_init (GstTextOverlayClass * klass)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;

  gobject_class = (GObjectClass *) klass;
  gstelement_class = (GstElementClass *) klass;

  gobject_class->finalize = gst_text_overlay_finalize;
  gobject_class->set_property = gst_text_overlay_set_property;

  gstelement_class->change_state =
      GST_DEBUG_FUNCPTR (gst_text_overlay_change_state);

  klass->get_text = gst_text_overlay_get_text;
  klass->pango_context = pango_ft2_get_context (72, 72);

  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_TEXT,
      g_param_spec_string ("text", "text",
          "Text to be display.", "", G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_SHADING,
      g_param_spec_boolean ("shaded-background", "shaded background",
          "Whether to shade the background under the text area", FALSE,
          G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_VALIGN,
      g_param_spec_string ("valign", "vertical alignment",
          "Vertical alignment of the text. "
          "Can be either 'baseline', 'bottom', or 'top'",
          "baseline", G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_HALIGN,
      g_param_spec_string ("halign", "horizontal alignment",
          "Horizontal alignment of the text. "
          "Can be either 'left', 'right', or 'center'",
          "center", G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_XPAD,
      g_param_spec_int ("xpad", "horizontal paddding",
          "Horizontal paddding when using left/right alignment",
          0, G_MAXINT, DEFAULT_XPAD, G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_YPAD,
      g_param_spec_int ("ypad", "vertical padding",
          "Vertical padding when using top/bottom alignment",
          0, G_MAXINT, DEFAULT_YPAD, G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_DELTAX,
      g_param_spec_int ("deltax", "X position modifier",
          "Shift X position to the left or to the right. Unit is pixels.",
          G_MININT, G_MAXINT, 0, G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_DELTAY,
      g_param_spec_int ("deltay", "Y position modifier",
          "Shift Y position up or down. Unit is pixels.",
          G_MININT, G_MAXINT, 0, G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_WRAP_MODE,
      g_param_spec_string ("wrap-mode", "wrap mode",
          "Whether to wrap the text and if so how."
          "Can be either 'none', 'word', 'char' or 'wordchar'",
          "wordchar", G_PARAM_WRITABLE));
  g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_FONT_DESC,
      g_param_spec_string ("font-desc", "font description",
          "Pango font description of font "
          "to be used for rendering. "
          "See documentation of "
          "pango_font_description_from_string"
          " for syntax.", "", G_PARAM_WRITABLE));
}

static void
gst_text_overlay_finalize (GObject * object)
{
  GstTextOverlay *overlay = GST_TEXT_OVERLAY (object);

  g_free (overlay->default_text);
  g_free (overlay->bitmap.buffer);

  if (overlay->layout)
    g_object_unref (overlay->layout);

  if (overlay->segment) {
    gst_segment_free (overlay->segment);
    overlay->segment = NULL;
  }

  if (overlay->text_buffer) {
    gst_buffer_unref (overlay->text_buffer);
    overlay->text_buffer = NULL;
  }

  if (overlay->cond) {
    g_cond_free (overlay->cond);
    overlay->cond = NULL;
  }

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
gst_text_overlay_init (GstTextOverlay * overlay, GstTextOverlayClass * klass)
{
  /* video sink */
  overlay->video_sinkpad =
      gst_pad_new_from_template (gst_static_pad_template_get
      (&video_sink_template_factory), "video_sink");
  gst_pad_set_getcaps_function (overlay->video_sinkpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_getcaps));
  gst_pad_set_setcaps_function (overlay->video_sinkpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_setcaps));
  gst_pad_set_event_function (overlay->video_sinkpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_video_event));
  gst_pad_set_chain_function (overlay->video_sinkpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_video_chain));
  gst_element_add_pad (GST_ELEMENT (overlay), overlay->video_sinkpad);

  if (!GST_IS_TIME_OVERLAY_CLASS (klass) && !GST_IS_CLOCK_OVERLAY_CLASS (klass)) {
    /* text sink */
    overlay->text_sinkpad =
        gst_pad_new_from_template (gst_static_pad_template_get
        (&text_sink_template_factory), "text_sink");
    gst_pad_set_event_function (overlay->text_sinkpad,
        GST_DEBUG_FUNCPTR (gst_text_overlay_text_event));
    gst_pad_set_chain_function (overlay->text_sinkpad,
        GST_DEBUG_FUNCPTR (gst_text_overlay_text_chain));
    gst_pad_set_link_function (overlay->text_sinkpad,
        GST_DEBUG_FUNCPTR (gst_text_overlay_text_pad_link));
    gst_pad_set_unlink_function (overlay->text_sinkpad,
        GST_DEBUG_FUNCPTR (gst_text_overlay_text_pad_unlink));
    gst_element_add_pad (GST_ELEMENT (overlay), overlay->text_sinkpad);
  }

  /* (video) source */
  overlay->srcpad =
      gst_pad_new_from_template (gst_static_pad_template_get
      (&src_template_factory), "src");
  gst_pad_set_getcaps_function (overlay->srcpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_getcaps));
  gst_pad_set_event_function (overlay->srcpad,
      GST_DEBUG_FUNCPTR (gst_text_overlay_src_event));
  gst_element_add_pad (GST_ELEMENT (overlay), overlay->srcpad);

  overlay->layout =
      pango_layout_new (GST_TEXT_OVERLAY_GET_CLASS (overlay)->pango_context);
  memset (&overlay->bitmap, 0, sizeof (overlay->bitmap));

  overlay->halign = GST_TEXT_OVERLAY_HALIGN_CENTER;
  overlay->valign = GST_TEXT_OVERLAY_VALIGN_BASELINE;
  overlay->xpad = DEFAULT_XPAD;
  overlay->ypad = DEFAULT_YPAD;
  overlay->deltax = 0;
  overlay->deltay = 0;

  overlay->wrap_mode = DEFAULT_WRAP_MODE;

  overlay->want_shading = FALSE;
  overlay->shading_value = DEFAULT_SHADING_VALUE;

  overlay->default_text = g_strdup ("");
  overlay->need_render = TRUE;

  overlay->fps_n = 0;
  overlay->fps_d = 1;

  overlay->text_buffer = NULL;
  overlay->text_linked = FALSE;
  overlay->video_flushing = FALSE;
  overlay->text_flushing = FALSE;
  overlay->cond = g_cond_new ();
  overlay->segment = gst_segment_new ();
  if (overlay->segment) {
    gst_segment_init (overlay->segment, GST_FORMAT_TIME);
  } else {
    GST_WARNING_OBJECT (overlay, "segment creation failed");
    g_assert_not_reached ();
  }
}

static void
gst_text_overlay_update_wrap_mode (GstTextOverlay * overlay)
{
  if (overlay->wrap_mode == GST_TEXT_OVERLAY_WRAP_MODE_NONE) {
    GST_DEBUG_OBJECT (overlay, "Set wrap mode NONE");
    pango_layout_set_width (overlay->layout, -1);
  } else {
    GST_DEBUG_OBJECT (overlay, "Set layout width %d", overlay->width);
    GST_DEBUG_OBJECT (overlay, "Set wrap mode    %d", overlay->wrap_mode);
    pango_layout_set_width (overlay->layout, overlay->width * PANGO_SCALE);
    pango_layout_set_wrap (overlay->layout, (PangoWrapMode) overlay->wrap_mode);
  }
}


/* FIXME: upstream nego (e.g. when the video window is resized) */

static gboolean
gst_text_overlay_setcaps (GstPad * pad, GstCaps * caps)
{
  GstTextOverlay *overlay;
  GstStructure *structure;
  gboolean ret = FALSE;
  const GValue *fps;

  if (!GST_PAD_IS_SINK (pad))
    return TRUE;

  g_return_val_if_fail (gst_caps_is_fixed (caps), FALSE);

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  overlay->width = 0;
  overlay->height = 0;
  structure = gst_caps_get_structure (caps, 0);
  fps = gst_structure_get_value (structure, "framerate");

  if (gst_structure_get_int (structure, "width", &overlay->width) &&
      gst_structure_get_int (structure, "height", &overlay->height) &&
      fps != NULL) {
    ret = gst_pad_set_caps (overlay->srcpad, caps);
  }

  overlay->fps_n = gst_value_get_fraction_numerator (fps);
  overlay->fps_d = gst_value_get_fraction_denominator (fps);

  if (ret) {
    GST_OBJECT_LOCK (overlay);
    gst_text_overlay_update_wrap_mode (overlay);
    GST_OBJECT_UNLOCK (overlay);
  }

  gst_object_unref (overlay);

  return ret;
}

static void
gst_text_overlay_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstTextOverlay *overlay = GST_TEXT_OVERLAY (object);

  GST_OBJECT_LOCK (overlay);

  switch (prop_id) {
    case ARG_TEXT:
      g_free (overlay->default_text);
      overlay->default_text = g_value_dup_string (value);
      overlay->need_render = TRUE;
      break;

    case ARG_SHADING:{
      overlay->want_shading = g_value_get_boolean (value);
      break;
    }
    case ARG_XPAD:{
      overlay->xpad = g_value_get_int (value);
      break;
    }
    case ARG_YPAD:{
      overlay->ypad = g_value_get_int (value);
      break;
    }
    case ARG_DELTAX:{
      overlay->deltax = g_value_get_int (value);
      break;
    }
    case ARG_DELTAY:{
      overlay->deltay = g_value_get_int (value);
      break;
    }

    case ARG_VALIGN:{
      const gchar *s = g_value_get_string (value);

      if (g_ascii_strcasecmp (s, "baseline") == 0)
        overlay->valign = GST_TEXT_OVERLAY_VALIGN_BASELINE;
      else if (g_ascii_strcasecmp (s, "bottom") == 0)
        overlay->valign = GST_TEXT_OVERLAY_VALIGN_BOTTOM;
      else if (g_ascii_strcasecmp (s, "top") == 0)
        overlay->valign = GST_TEXT_OVERLAY_VALIGN_TOP;
      else
        g_warning ("Invalid 'valign' property value: %s", s);
      break;
    }

    case ARG_HALIGN:{
      const gchar *s = g_value_get_string (value);

      if (g_ascii_strcasecmp (s, "left") == 0)
        overlay->halign = GST_TEXT_OVERLAY_HALIGN_LEFT;
      else if (g_ascii_strcasecmp (s, "right") == 0)
        overlay->halign = GST_TEXT_OVERLAY_HALIGN_RIGHT;
      else if (g_ascii_strcasecmp (s, "center") == 0)
        overlay->halign = GST_TEXT_OVERLAY_HALIGN_CENTER;
      else
        g_warning ("Invalid 'halign' property value: %s", s);
      break;
    }

    case ARG_WRAP_MODE:{
      const gchar *s = g_value_get_string (value);

      if (g_ascii_strcasecmp (s, "none") == 0)
        overlay->wrap_mode = GST_TEXT_OVERLAY_WRAP_MODE_NONE;
      else if (g_ascii_strcasecmp (s, "char") == 0)
        overlay->wrap_mode = GST_TEXT_OVERLAY_WRAP_MODE_CHAR;
      else if (g_ascii_strcasecmp (s, "word") == 0)
        overlay->wrap_mode = GST_TEXT_OVERLAY_WRAP_MODE_WORD;
      else if (g_ascii_strcasecmp (s, "wordchar") == 0)
        overlay->wrap_mode = GST_TEXT_OVERLAY_WRAP_MODE_WORD_CHAR;
      else
        g_warning ("Invalid 'wrap-mode' property value: %s", s);

      gst_text_overlay_update_wrap_mode (overlay);
      break;
    }

    case ARG_FONT_DESC:
    {
      PangoFontDescription *desc;
      const gchar *fontdesc_str;

      fontdesc_str = g_value_get_string (value);
      desc = pango_font_description_from_string (fontdesc_str);
      if (desc) {
        GST_LOG ("font description set: %s", fontdesc_str);
        pango_layout_set_font_description (overlay->layout, desc);
        pango_font_description_free (desc);
      } else {
        GST_WARNING ("font description parse failed: %s", fontdesc_str);
      }
      break;
    }

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }

  overlay->need_render = TRUE;

  GST_OBJECT_UNLOCK (overlay);
}

static gboolean
gst_text_overlay_src_event (GstPad * pad, GstEvent * event)
{
  gboolean ret = FALSE;
  GstTextOverlay *overlay = NULL;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_SEEK:
      /* We don't handle seek if we have not text pad */
      if (!overlay->text_linked) {
        ret = gst_pad_push_event (overlay->video_sinkpad, event);
        goto beach;
      }

      GST_DEBUG_OBJECT (overlay, "seek received, driving from here");

      /* Flush downstream */
      gst_pad_push_event (overlay->srcpad, gst_event_new_flush_start ());

      /* Mark ourself as flushing, unblock chains */
      GST_OBJECT_LOCK (overlay);
      overlay->video_flushing = TRUE;
      overlay->text_flushing = TRUE;
      gst_text_overlay_pop_text (overlay);
      GST_OBJECT_UNLOCK (overlay);

      /* Seek on each sink pad */
      gst_event_ref (event);
      ret = gst_pad_push_event (overlay->video_sinkpad, event);
      if (ret) {
        ret = gst_pad_push_event (overlay->text_sinkpad, event);
      } else {
        gst_event_unref (event);
      }
      break;
    default:
      gst_event_ref (event);
      ret = gst_pad_push_event (overlay->video_sinkpad, event);
      if (overlay->text_linked) {
        ret = gst_pad_push_event (overlay->text_sinkpad, event);
      }
  }

beach:
  gst_object_unref (overlay);

  return ret;
}

static GstCaps *
gst_text_overlay_getcaps (GstPad * pad)
{
  GstTextOverlay *overlay;
  GstPad *otherpad;
  GstCaps *caps;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  if (pad == overlay->srcpad)
    otherpad = overlay->video_sinkpad;
  else
    otherpad = overlay->srcpad;

  /* we can do what the peer can */
  caps = gst_pad_peer_get_caps (otherpad);
  if (caps) {
    GstCaps *temp;
    const GstCaps *templ;

    GST_DEBUG_OBJECT (pad, "peer caps  %" GST_PTR_FORMAT, caps);

    /* filtered against our padtemplate */
    templ = gst_pad_get_pad_template_caps (otherpad);
    GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);
    temp = gst_caps_intersect (caps, templ);
    GST_DEBUG_OBJECT (pad, "intersected %" GST_PTR_FORMAT, temp);
    gst_caps_unref (caps);
    /* this is what we can do */
    caps = temp;
  } else {
    /* no peer, our padtemplate is enough then */
    caps = gst_caps_copy (gst_pad_get_pad_template_caps (pad));
  }

  GST_DEBUG_OBJECT (overlay, "returning  %" GST_PTR_FORMAT, caps);

  gst_object_unref (overlay);

  return caps;
}

#define BOX_XPAD         6
#define BOX_YPAD         6

static inline void
gst_text_overlay_shade_y (GstTextOverlay * overlay, guchar * dest,
    guint dest_stride, gint x0, gint x1, gint y0, gint y1)
{
  gint i, j;

  x0 = CLAMP (x0 - BOX_XPAD, 0, overlay->width);
  x1 = CLAMP (x1 + BOX_XPAD, 0, overlay->width);

  y0 = CLAMP (y0 - BOX_YPAD, 0, overlay->height);
  y1 = CLAMP (y1 + BOX_YPAD, 0, overlay->height);

  for (i = y0; i < y1; ++i) {
    for (j = x0; j < x1; ++j) {
      gint y = dest[(i * dest_stride) + j] + overlay->shading_value;

      dest[(i * dest_stride) + j] = CLAMP (y, 0, 255);
    }
  }
}

/* FIXME:
 *  - use proper strides and offset for I420
 *  - don't draw over the edge of the picture (try a longer
 *    text with a huge font size)
 */

static inline void
gst_text_overlay_blit_yuv420 (GstTextOverlay * overlay, FT_Bitmap * bitmap,
    guint8 * yuv_pixels, gint x0, gint y0)
{
  int y;                        /* text bitmap coordinates */
  int x1, y1;                   /* video buffer coordinates */
  int bit_rowinc, uv_rowinc;
  guint8 *p, *bitp, *u_p;
  int video_width, video_height;
  int bitmap_x0 = 0;            //x0 < 1 ? -(x0 - 1) : 1;       /* 1 pixel border */
  int bitmap_y0 = y0 < 1 ? -(y0 - 1) : 1;       /* 1 pixel border */
  int bitmap_width = bitmap->width - bitmap_x0;
  int bitmap_height = bitmap->rows - bitmap_y0;
  int u_plane_size;
  int skip_y, skip_x;
  guint8 v;

  video_width = I420_Y_ROWSTRIDE (overlay->width);
  video_height = overlay->height;

/*
  if (x0 < 0 && abs (x0) < bitmap_width) {
    bitmap_x0 = abs (x0);
    x0 = 0;
  }
*/

  if (x0 + bitmap_x0 + bitmap_width > overlay->width - 1)       /* 1 pixel border */
    bitmap_width -= x0 + bitmap_x0 + bitmap_width - overlay->width + 1;
  if (y0 + bitmap_y0 + bitmap_height > video_height - 1)        /* 1 pixel border */
    bitmap_height -= y0 + bitmap_y0 + bitmap_height - video_height + 1;

  uv_rowinc = video_width / 2 - bitmap_width / 2;
  bit_rowinc = bitmap->pitch - bitmap_width;
  u_plane_size = (video_width / 2) * (video_height / 2);

  y1 = y0 + bitmap_y0;
  x1 = x0 + bitmap_x0;
  bitp = bitmap->buffer + bitmap->pitch * bitmap_y0 + bitmap_x0;
  for (y = bitmap_y0; y < bitmap_y0 + bitmap_height; y++) {
    int n;

    p = yuv_pixels + (y + y0) * I420_Y_ROWSTRIDE (overlay->width) + x1;
    for (n = bitmap_width; n > 0; --n) {
      v = *bitp;
      if (v) {
        p[-1] = CLAMP (p[-1] - v, 0, 255);
        p[1] = CLAMP (p[1] - v, 0, 255);
        p[-video_width] = CLAMP (p[-video_width] - v, 0, 255);
        p[video_width] = CLAMP (p[video_width] - v, 0, 255);
      }
      p++;
      bitp++;
    }
    bitp += bit_rowinc;
  }

  y = bitmap_y0;
  y1 = y0 + bitmap_y0;
  x1 = x0 + bitmap_x0;
  bitp = bitmap->buffer + bitmap->pitch * bitmap_y0 + bitmap_x0;
  p = yuv_pixels + video_width * y1 + x1;
  u_p =
      yuv_pixels + video_width * video_height + (video_width >> 1) * (y1 >> 1) +
      (x1 >> 1);
  skip_y = 0;
  skip_x = 0;

  for (; y < bitmap_y0 + bitmap_height; y++) {
    int n;

    x1 = x0 + bitmap_x0;
    skip_x = 0;
    for (n = bitmap_width; n > 0; --n) {
      v = *bitp;
      if (v) {
        *p = v;
        if (!skip_y) {
          u_p[0] = u_p[u_plane_size] = 0x80;
        }
      }
      if (!skip_y) {
        skip_x = !skip_x;
        if (!skip_x)
          u_p++;
      }
      p++;
      bitp++;
    }
    /*if (!skip_x && !skip_y) u_p--; */
    p += I420_Y_ROWSTRIDE (overlay->width) - bitmap_width;
    bitp += bit_rowinc;
    skip_y = !skip_y;
    u_p += skip_y ? uv_rowinc : 0;
  }
}

static void
gst_text_overlay_resize_bitmap (GstTextOverlay * overlay, gint width,
    gint height)
{
  FT_Bitmap *bitmap = &overlay->bitmap;
  int pitch = (width | 3) + 1;
  int size = pitch * height;

  /* no need to keep reallocating; just keep the maximum size so far */
  if (size <= overlay->bitmap_buffer_size) {
    bitmap->rows = height;
    bitmap->width = width;
    bitmap->pitch = pitch;
    memset (bitmap->buffer, 0, overlay->bitmap_buffer_size);
    return;
  }
  if (!bitmap->buffer) {
    /* initialize */
    bitmap->pixel_mode = ft_pixel_mode_grays;
    bitmap->num_grays = 256;
  }
  overlay->bitmap_buffer_size = size;
  bitmap->buffer = g_realloc (bitmap->buffer, size);
  memset (bitmap->buffer, 0, size);
  bitmap->rows = height;
  bitmap->width = width;
  bitmap->pitch = pitch;
}

static void
gst_text_overlay_render_text (GstTextOverlay * overlay,
    const gchar * text, gint textlen)
{
  PangoRectangle ink_rect, logical_rect;
  gchar *string;

  /* -1 is the whole string */
  if (text != NULL && textlen < 0) {
    textlen = strlen (text);
  }

  if (text != NULL) {
    string = g_strndup (text, textlen);
  } else {                      /* empty string */
    string = g_strdup (" ");
  }
  g_strdelimit (string, "\n\r\t", ' ');
  textlen = strlen (string);

  /* FIXME: should we check for UTF-8 here? */

  if (!overlay->need_render) {
    GST_DEBUG ("Using previously rendered text.");
    return;
  }

  GST_DEBUG ("Rendering '%s'", string);
  pango_layout_set_markup (overlay->layout, string, textlen);

  pango_layout_get_pixel_extents (overlay->layout, &ink_rect, &logical_rect);
  gst_text_overlay_resize_bitmap (overlay, ink_rect.width,
      ink_rect.height + ink_rect.y);
  pango_ft2_render_layout (&overlay->bitmap, overlay->layout, -ink_rect.x, 0);
  overlay->baseline_y = ink_rect.y;

  g_free (string);

  overlay->need_render = FALSE;
}

static GstFlowReturn
gst_text_overlay_push_frame (GstTextOverlay * overlay, GstBuffer * video_frame)
{
  gint xpos, ypos;

  video_frame = gst_buffer_make_writable (video_frame);

  switch (overlay->halign) {
    case GST_TEXT_OVERLAY_HALIGN_LEFT:
      xpos = overlay->xpad;
      break;
    case GST_TEXT_OVERLAY_HALIGN_CENTER:
      xpos = (overlay->width - overlay->bitmap.width) / 2;
      break;
    case GST_TEXT_OVERLAY_HALIGN_RIGHT:
      xpos = overlay->width - overlay->bitmap.width - overlay->xpad;
      break;
    default:
      xpos = 0;
  }
  xpos += overlay->deltax;


  switch (overlay->valign) {
    case GST_TEXT_OVERLAY_VALIGN_BOTTOM:
      ypos = overlay->height - overlay->bitmap.rows - overlay->ypad;
      break;
    case GST_TEXT_OVERLAY_VALIGN_BASELINE:
      ypos = overlay->height - (overlay->bitmap.rows + overlay->ypad);
      break;
    case GST_TEXT_OVERLAY_VALIGN_TOP:
      ypos = overlay->ypad;
      break;
    default:
      ypos = overlay->ypad;
      break;
  }
  ypos += overlay->deltay;

  /* shaded background box */
  if (overlay->want_shading) {
    gst_text_overlay_shade_y (overlay,
        GST_BUFFER_DATA (video_frame),
        I420_Y_ROWSTRIDE (overlay->width),
        xpos, xpos + overlay->bitmap.width, ypos, ypos + overlay->bitmap.rows);
  }


  if (overlay->bitmap.buffer) {
    gst_text_overlay_blit_yuv420 (overlay, &overlay->bitmap,
        GST_BUFFER_DATA (video_frame), xpos, ypos);
  }

  return gst_pad_push (overlay->srcpad, video_frame);
}

static GstPadLinkReturn
gst_text_overlay_text_pad_link (GstPad * pad, GstPad * peer)
{
  GstTextOverlay *overlay;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  GST_DEBUG_OBJECT (overlay, "Text pad linked");

  overlay->text_linked = TRUE;

  gst_object_unref (overlay);

  return GST_PAD_LINK_OK;
}

static void
gst_text_overlay_text_pad_unlink (GstPad * pad)
{
  GstTextOverlay *overlay;

  /* don't use gst_pad_get_parent() here, will deadlock */
  overlay = GST_TEXT_OVERLAY (GST_PAD_PARENT (pad));

  GST_DEBUG_OBJECT (overlay, "Text pad unlinked");

  overlay->text_linked = FALSE;
}

static gboolean
gst_text_overlay_text_event (GstPad * pad, GstEvent * event)
{
  gboolean ret = FALSE;
  GstTextOverlay *overlay = NULL;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_NEWSEGMENT:
      /* We just ignore those events from the text pad */
      gst_event_unref (event);
      ret = TRUE;
      break;
    case GST_EVENT_FLUSH_STOP:
      GST_OBJECT_LOCK (overlay);
      overlay->text_flushing = FALSE;
      gst_text_overlay_pop_text (overlay);
      GST_OBJECT_UNLOCK (overlay);
      gst_event_unref (event);
      ret = TRUE;
      break;
    case GST_EVENT_FLUSH_START:
      GST_OBJECT_LOCK (overlay);
      overlay->text_flushing = TRUE;
      GST_TEXT_OVERLAY_BROADCAST (overlay);
      GST_OBJECT_UNLOCK (overlay);
      gst_event_unref (event);
      ret = TRUE;
      break;
    case GST_EVENT_EOS:
      GST_OBJECT_LOCK (overlay);
      /* We use flushing to make sure we return WRONG_STATE */
      overlay->text_flushing = TRUE;
      gst_text_overlay_pop_text (overlay);
      GST_OBJECT_UNLOCK (overlay);
      gst_event_unref (event);
      ret = TRUE;
      break;
    default:
      ret = gst_pad_event_default (pad, event);
      goto beach;
  }

beach:
  gst_object_unref (overlay);

  return ret;
}

static gboolean
gst_text_overlay_video_event (GstPad * pad, GstEvent * event)
{
  gboolean ret = FALSE;
  GstTextOverlay *overlay = NULL;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_NEWSEGMENT:
    {
      GstFormat format;
      gdouble rate;
      gint64 start, stop, time;
      gboolean update;

      GST_DEBUG_OBJECT (overlay, "received new segment");

      gst_event_parse_new_segment (event, &update, &rate, &format, &start,
          &stop, &time);

      /* now copy over the values */
      gst_segment_set_newsegment (overlay->segment, update, rate, format,
          start, stop, time);

      ret = gst_pad_event_default (pad, event);
      break;
    }
    case GST_EVENT_EOS:
      GST_OBJECT_LOCK (overlay);
      overlay->video_flushing = TRUE;
      overlay->text_flushing = TRUE;
      gst_text_overlay_pop_text (overlay);
      GST_OBJECT_UNLOCK (overlay);
      ret = gst_pad_event_default (pad, event);
      break;
    case GST_EVENT_FLUSH_START:
      GST_OBJECT_LOCK (overlay);
      overlay->video_flushing = TRUE;
      GST_OBJECT_UNLOCK (overlay);
      ret = gst_pad_event_default (pad, event);
      break;
    case GST_EVENT_FLUSH_STOP:
      GST_OBJECT_LOCK (overlay);
      overlay->video_flushing = FALSE;
      GST_OBJECT_UNLOCK (overlay);
      ret = gst_pad_event_default (pad, event);
      break;
    default:
      ret = gst_pad_event_default (pad, event);
  }

  gst_object_unref (overlay);

  return ret;
}

/* Called with lock held */
static void
gst_text_overlay_pop_text (GstTextOverlay * overlay)
{
  g_return_if_fail (GST_IS_TEXT_OVERLAY (overlay));

  if (overlay->text_buffer) {
    GST_DEBUG_OBJECT (overlay, "releasing text buffer %p",
        overlay->text_buffer);
    gst_buffer_unref (overlay->text_buffer);
    overlay->text_buffer = NULL;
  }

  /* Let the text task know we used that buffer */
  GST_TEXT_OVERLAY_BROADCAST (overlay);
}

/* We receive text buffers here. If they are out of segment we just ignore them.
   If the buffer is in our segment we keep it internally except if another one
   is already waiting here, in that case we wait that it gets kicked out */
static GstFlowReturn
gst_text_overlay_text_chain (GstPad * pad, GstBuffer * buffer)
{
  GstFlowReturn ret = GST_FLOW_OK;
  GstTextOverlay *overlay = NULL;
  gboolean in_seg = FALSE;
  gint64 clip_start = 0, clip_stop = 0;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));

  GST_OBJECT_LOCK (overlay);

  if (overlay->text_flushing) {
    GST_OBJECT_UNLOCK (overlay);
    ret = GST_FLOW_WRONG_STATE;
    goto beach;
  }

  in_seg = gst_segment_clip (overlay->segment, GST_FORMAT_TIME,
      GST_BUFFER_TIMESTAMP (buffer),
      GST_BUFFER_TIMESTAMP (buffer) + GST_BUFFER_DURATION (buffer),
      &clip_start, &clip_stop);

  if (in_seg) {
    GST_BUFFER_TIMESTAMP (buffer) = clip_start;
    GST_BUFFER_DURATION (buffer) = clip_stop - clip_start;

    /* Wait for the previous buffer to go away */
    while (overlay->text_buffer != NULL) {
      GST_DEBUG ("Pad %s:%s has a buffer queued, waiting",
          GST_DEBUG_PAD_NAME (pad));
      GST_TEXT_OVERLAY_WAIT (overlay);
      GST_DEBUG ("Pad %s:%s resuming", GST_DEBUG_PAD_NAME (pad));
      if (overlay->text_flushing) {
        GST_OBJECT_UNLOCK (overlay);
        ret = GST_FLOW_WRONG_STATE;
        goto beach;
      }
    }

    overlay->text_buffer = buffer;
    /* That's a new text buffer we need to render */
    overlay->need_render = TRUE;
  }

  GST_OBJECT_UNLOCK (overlay);

beach:
  gst_object_unref (overlay);

  return ret;
}

static GstFlowReturn
gst_text_overlay_video_chain (GstPad * pad, GstBuffer * buffer)
{
  GstFlowReturn ret = GST_FLOW_OK;
  GstTextOverlay *overlay = NULL;
  gboolean in_seg = FALSE;
  gint64 clip_start = 0, clip_stop = 0;
  GstTextOverlayClass *klass = NULL;

  overlay = GST_TEXT_OVERLAY (gst_pad_get_parent (pad));
  klass = GST_TEXT_OVERLAY_GET_CLASS (overlay);

  GST_OBJECT_LOCK (overlay);

  if (overlay->video_flushing) {
    GST_OBJECT_UNLOCK (overlay);
    ret = GST_FLOW_WRONG_STATE;
    goto beach;
  }

  in_seg = gst_segment_clip (overlay->segment, GST_FORMAT_TIME,
      GST_BUFFER_TIMESTAMP (buffer),
      GST_BUFFER_TIMESTAMP (buffer) + GST_BUFFER_DURATION (buffer),
      &clip_start, &clip_stop);

  if (in_seg) {
    gchar *text = NULL;

    GST_BUFFER_TIMESTAMP (buffer) = clip_start;
    GST_BUFFER_DURATION (buffer) = clip_stop - clip_start;

    /* Text pad not linked, rendering internal text */
    if (!overlay->text_linked) {
      if (klass->get_text) {
        text = klass->get_text (overlay, buffer);
      } else {
        text = g_strdup (overlay->default_text);
      }

      GST_DEBUG_OBJECT (overlay, "Text pad not linked, rendering default "
          "text: '%s'", GST_STR_NULL (text));

      GST_OBJECT_UNLOCK (overlay);

      if (text != NULL && *text != '\0') {
        /* Render and push */
        gst_text_overlay_render_text (overlay, text, -1);
        ret = gst_text_overlay_push_frame (overlay, buffer);
      } else {
        /* Invalid or empty string */
        ret = gst_pad_push (overlay->srcpad, buffer);
      }
    } else {
      if (overlay->text_buffer) {
        gboolean pop_text = FALSE;
        gint64 text_end = 0;

        /* if the text buffer isn't stamped right, pop it off the
         * queue and display it for the current video frame only */
        if (GST_BUFFER_TIMESTAMP (overlay->text_buffer) == GST_CLOCK_TIME_NONE
            || GST_BUFFER_DURATION (overlay->text_buffer) ==
            GST_CLOCK_TIME_NONE) {
          GST_WARNING_OBJECT (overlay,
              "Got text buffer with invalid time " "stamp or duration");
          gst_buffer_stamp (overlay->text_buffer, buffer);
          pop_text = TRUE;
        }

        text_end = GST_BUFFER_TIMESTAMP (overlay->text_buffer) +
            GST_BUFFER_DURATION (overlay->text_buffer);

        /* Text too old or in the future */
        if ((text_end < clip_start) ||
            (clip_stop < GST_BUFFER_TIMESTAMP (overlay->text_buffer))) {
          if (text_end < clip_start) {
            /* Get rid of it, if it's too old only */
            pop_text = FALSE;
            gst_text_overlay_pop_text (overlay);
          }
          GST_OBJECT_UNLOCK (overlay);
          /* Push the video frame */
          ret = gst_pad_push (overlay->srcpad, buffer);
        } else {
          /* Get the string */
          text = g_strndup ((gchar *) GST_BUFFER_DATA (overlay->text_buffer),
              GST_BUFFER_SIZE (overlay->text_buffer));

          if (text != NULL && *text != '\0') {
            gint text_len = strlen (text);

            while (text_len > 0 && (text[text_len - 1] == '\n' ||
                    text[text_len - 1] == '\r')) {
              --text_len;
            }
            GST_DEBUG_OBJECT (overlay, "Rendering text '%*s'", text_len, text);
            gst_text_overlay_render_text (overlay, text, text_len);
          } else {
            GST_DEBUG_OBJECT (overlay, "No text to render (empty buffer)");
            gst_text_overlay_render_text (overlay, " ", 1);
          }

          GST_OBJECT_UNLOCK (overlay);
          ret = gst_text_overlay_push_frame (overlay, buffer);
        }
      } else {
        /* No text to overlay, push the frame as is */
        GST_OBJECT_UNLOCK (overlay);
        ret = gst_pad_push (overlay->srcpad, buffer);
      }
    }

    g_free (text);

    /* Update last_stop */
    gst_segment_set_last_stop (overlay->segment, GST_FORMAT_TIME,
        GST_BUFFER_TIMESTAMP (buffer));
  } else {                      /* Out of segment */
    GST_OBJECT_UNLOCK (overlay);
    GST_DEBUG_OBJECT (overlay, "buffer out of segment discarding");
    gst_buffer_unref (buffer);
  }

beach:
  gst_object_unref (overlay);

  return ret;
}

static GstStateChangeReturn
gst_text_overlay_change_state (GstElement * element, GstStateChange transition)
{
  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
  GstTextOverlay *overlay = GST_TEXT_OVERLAY (element);

  switch (transition) {
    case GST_STATE_CHANGE_READY_TO_PAUSED:
      break;
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      GST_OBJECT_LOCK (overlay);
      overlay->text_flushing = TRUE;
      gst_text_overlay_pop_text (overlay);
      GST_OBJECT_UNLOCK (overlay);
      break;
    default:
      break;
  }

  ret = parent_class->change_state (element, transition);
  if (ret == GST_STATE_CHANGE_FAILURE)
    return ret;

  switch (transition) {
    default:
      break;
  }

  return ret;
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  if (!gst_element_register (plugin, "textoverlay", GST_RANK_NONE,
          GST_TYPE_TEXT_OVERLAY) ||
      !gst_element_register (plugin, "timeoverlay", GST_RANK_NONE,
          GST_TYPE_TIME_OVERLAY) ||
      !gst_element_register (plugin, "clockoverlay", GST_RANK_NONE,
          GST_TYPE_CLOCK_OVERLAY) ||
      !gst_element_register (plugin, "textrender", GST_RANK_NONE,
          GST_TYPE_TEXT_RENDER)) {
    return FALSE;
  }

  /*texttestsrc_plugin_init(module, plugin); */

  GST_DEBUG_CATEGORY_INIT (pango_debug, "pango", 0, "Pango elements");

  return TRUE;
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR, GST_VERSION_MINOR,
    "pango", "Pango-based text rendering and overlay", plugin_init,
    VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)