gstreamer/gst/compositor/compositor.c

/* Video compositor plugin
 * Copyright (C) 2004, 2008 Wim Taymans <wim@fluendo.com>
 * Copyright (C) 2010 Sebastian Dröge <sebastian.droege@collabora.co.uk>
 * Copyright (C) 2014 Mathieu Duponchelle <mathieu.duponchelle@opencreed.com>
 * Copyright (C) 2014 Thibault Saunier <tsaunier@gnome.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., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

/**
 * SECTION:element-compositor
 *
 * Compositor can accept AYUV, ARGB and BGRA video streams. For each of the requested
 * sink pads it will compare the incoming geometry and framerate to define the
 * output parameters. Indeed output video frames will have the geometry of the
 * biggest incoming video stream and the framerate of the fastest incoming one.
 *
 * Compositor will do colorspace conversion.
 * 
 * Individual parameters for each input stream can be configured on the
 * #GstCompositorPad.
 *
 * <refsect2>
 * <title>Sample pipelines</title>
 * |[
 * gst-launch-1.0 \
 *   videotestsrc pattern=1 ! \
 *   video/x-raw,format=AYUV,framerate=\(fraction\)10/1,width=100,height=100 ! \
 *   videobox border-alpha=0 top=-70 bottom=-70 right=-220 ! \
 *   compositor name=comp sink_0::alpha=0.7 sink_1::alpha=0.5 ! \
 *   videoconvert ! xvimagesink \
 *   videotestsrc ! \
 *   video/x-raw,format=AYUV,framerate=\(fraction\)5/1,width=320,height=240 ! comp.
 * ]| A pipeline to demonstrate compositor used together with videobox.
 * This should show a 320x240 pixels video test source with some transparency
 * showing the background checker pattern. Another video test source with just
 * the snow pattern of 100x100 pixels is overlayed on top of the first one on
 * the left vertically centered with a small transparency showing the first
 * video test source behind and the checker pattern under it. Note that the
 * framerate of the output video is 10 frames per second.
 * |[
 * gst-launch-1.0 videotestsrc pattern=1 ! \
 *   video/x-raw, framerate=\(fraction\)10/1, width=100, height=100 ! \
 *   compositor name=comp ! videoconvert ! ximagesink \
 *   videotestsrc !  \
 *   video/x-raw, framerate=\(fraction\)5/1, width=320, height=240 ! comp.
 * ]| A pipeline to demostrate bgra comping. (This does not demonstrate alpha blending). 
 * |[
 * gst-launch-1.0 videotestsrc pattern=1 ! \
 *   video/x-raw,format =I420, framerate=\(fraction\)10/1, width=100, height=100 ! \
 *   compositor name=comp ! videoconvert ! ximagesink \
 *   videotestsrc ! \
 *   video/x-raw,format=I420, framerate=\(fraction\)5/1, width=320, height=240 ! comp.
 * ]| A pipeline to test I420
 * |[
 * gst-launch-1.0 compositor name=comp sink_1::alpha=0.5 sink_1::xpos=50 sink_1::ypos=50 ! \
 *   videoconvert ! ximagesink \
 *   videotestsrc pattern=snow timestamp-offset=3000000000 ! \
 *   "video/x-raw,format=AYUV,width=640,height=480,framerate=(fraction)30/1" ! \
 *   timeoverlay ! queue2 ! comp. \
 *   videotestsrc pattern=smpte ! \
 *   "video/x-raw,format=AYUV,width=800,height=600,framerate=(fraction)10/1" ! \
 *   timeoverlay ! queue2 ! comp.
 * ]| A pipeline to demonstrate synchronized compositing (the second stream starts after 3 seconds)
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

#include "compositor.h"
#include "compositorpad.h"

#ifdef DISABLE_ORC
#define orc_memset memset
#else
#include <orc/orcfunctions.h>
#endif

GST_DEBUG_CATEGORY_STATIC (gst_compositor_debug);
#define GST_CAT_DEFAULT gst_compositor_debug

#define FORMATS " { AYUV, BGRA, ARGB, RGBA, ABGR, Y444, Y42B, YUY2, UYVY, "\
                "   YVYU, I420, YV12, NV12, NV21, Y41B, RGB, BGR, xRGB, xBGR, "\
                "   RGBx, BGRx } "

static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE (FORMATS))
    );

static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink_%u",
    GST_PAD_SINK,
    GST_PAD_REQUEST,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE (FORMATS))
    );

#define DEFAULT_PAD_XPOS   0
#define DEFAULT_PAD_YPOS   0
#define DEFAULT_PAD_WIDTH  0
#define DEFAULT_PAD_HEIGHT 0
#define DEFAULT_PAD_ALPHA  1.0
enum
{
  PROP_PAD_0,
  PROP_PAD_XPOS,
  PROP_PAD_YPOS,
  PROP_PAD_WIDTH,
  PROP_PAD_HEIGHT,
  PROP_PAD_ALPHA
};

G_DEFINE_TYPE (GstCompositorPad, gst_compositor_pad,
    GST_TYPE_VIDEO_AGGREGATOR_PAD);

static void
gst_compositor_pad_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstCompositorPad *pad = GST_COMPOSITOR_PAD (object);

  switch (prop_id) {
    case PROP_PAD_XPOS:
      g_value_set_int (value, pad->xpos);
      break;
    case PROP_PAD_YPOS:
      g_value_set_int (value, pad->ypos);
      break;
    case PROP_PAD_WIDTH:
      g_value_set_int (value, pad->width);
      break;
    case PROP_PAD_HEIGHT:
      g_value_set_int (value, pad->height);
      break;
    case PROP_PAD_ALPHA:
      g_value_set_double (value, pad->alpha);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_compositor_pad_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstCompositorPad *pad = GST_COMPOSITOR_PAD (object);

  switch (prop_id) {
    case PROP_PAD_XPOS:
      pad->xpos = g_value_get_int (value);
      break;
    case PROP_PAD_YPOS:
      pad->ypos = g_value_get_int (value);
      break;
    case PROP_PAD_WIDTH:
      pad->width = g_value_get_int (value);
      break;
    case PROP_PAD_HEIGHT:
      pad->height = g_value_get_int (value);
      break;
    case PROP_PAD_ALPHA:
      pad->alpha = g_value_get_double (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static gboolean
gst_compositor_pad_set_info (GstVideoAggregatorPad * pad,
    GstVideoAggregator * vagg G_GNUC_UNUSED,
    GstVideoInfo * current_info, GstVideoInfo * wanted_info)
{
  GstCompositorPad *cpad = GST_COMPOSITOR_PAD (pad);
  gchar *colorimetry, *best_colorimetry;
  const gchar *chroma, *best_chroma;
  gint width, height;

  if (!current_info->finfo)
    return TRUE;

  if (GST_VIDEO_INFO_FORMAT (current_info) == GST_VIDEO_FORMAT_UNKNOWN)
    return TRUE;

  if (cpad->convert)
    gst_video_converter_free (cpad->convert);

  cpad->convert = NULL;

  colorimetry = gst_video_colorimetry_to_string (&(current_info->colorimetry));
  chroma = gst_video_chroma_to_string (current_info->chroma_site);

  best_colorimetry =
      gst_video_colorimetry_to_string (&(wanted_info->colorimetry));
  best_chroma = gst_video_chroma_to_string (wanted_info->chroma_site);

  if (cpad->width > 0)
    width = cpad->width;
  else
    width = current_info->width;

  if (cpad->height > 0)
    height = cpad->height;
  else
    height = current_info->height;

  if (GST_VIDEO_INFO_FORMAT (wanted_info) !=
      GST_VIDEO_INFO_FORMAT (current_info)
      || g_strcmp0 (colorimetry, best_colorimetry)
      || g_strcmp0 (chroma, best_chroma)
      || width != current_info->width || height != current_info->height) {
    GstVideoInfo tmp_info;

    /* Initialize with the wanted video format and our original width and
     * height as we don't want to rescale. Then copy over the wanted
     * colorimetry, and chroma-site and our current pixel-aspect-ratio
     * and other relevant fields.
     */
    gst_video_info_set_format (&tmp_info, GST_VIDEO_INFO_FORMAT (wanted_info),
        width, height);
    tmp_info.chroma_site = wanted_info->chroma_site;
    tmp_info.colorimetry = wanted_info->colorimetry;
    tmp_info.par_n = current_info->par_n;
    tmp_info.par_d = current_info->par_d;
    tmp_info.fps_n = current_info->fps_n;
    tmp_info.fps_d = current_info->fps_d;
    tmp_info.flags = current_info->flags;
    tmp_info.interlace_mode = current_info->interlace_mode;

    GST_DEBUG_OBJECT (pad, "This pad will be converted from %d to %d",
        GST_VIDEO_INFO_FORMAT (current_info),
        GST_VIDEO_INFO_FORMAT (&tmp_info));
    cpad->convert = gst_video_converter_new (current_info, &tmp_info, NULL);
    cpad->conversion_info = tmp_info;
    if (!cpad->convert) {
      g_free (colorimetry);
      g_free (best_colorimetry);
      GST_WARNING_OBJECT (pad, "No path found for conversion");
      return FALSE;
    }
  } else {
    cpad->conversion_info = *current_info;
    GST_DEBUG_OBJECT (pad, "This pad will not need conversion");
  }
  g_free (colorimetry);
  g_free (best_colorimetry);

  return TRUE;
}

static gboolean
gst_compositor_pad_prepare_frame (GstVideoAggregatorPad * pad,
    GstVideoAggregator * vagg)
{
  GstCompositorPad *cpad = GST_COMPOSITOR_PAD (pad);
  guint outsize;
  GstVideoFrame *converted_frame;
  GstBuffer *converted_buf = NULL;
  GstVideoFrame *frame = g_slice_new0 (GstVideoFrame);
  static GstAllocationParams params = { 0, 15, 0, 0, };
  gint width, height;

  if (!gst_video_frame_map (frame, &pad->buffer_vinfo, pad->buffer,
          GST_MAP_READ)) {
    GST_WARNING_OBJECT (vagg, "Could not map input buffer");
    return FALSE;
  }

  if (cpad->width > 0)
    width = cpad->width;
  else
    width = GST_VIDEO_FRAME_WIDTH (frame);

  if (cpad->height > 0)
    height = cpad->height;
  else
    height = GST_VIDEO_FRAME_HEIGHT (frame);

  /* The only thing that can change here is the width
   * and height, otherwise set_info would've been called */
  if (cpad->conversion_info.width != width ||
      cpad->conversion_info.height != height) {
    gchar *colorimetry, *wanted_colorimetry;
    const gchar *chroma, *wanted_chroma;

    /* We might end up with no converter afterwards if
     * the only reason for conversion was a different
     * width or height
     */
    if (cpad->convert)
      gst_video_converter_free (cpad->convert);
    cpad->convert = NULL;

    colorimetry = gst_video_colorimetry_to_string (&frame->info.colorimetry);
    chroma = gst_video_chroma_to_string (frame->info.chroma_site);

    wanted_colorimetry =
        gst_video_colorimetry_to_string (&cpad->conversion_info.colorimetry);
    wanted_chroma =
        gst_video_chroma_to_string (cpad->conversion_info.chroma_site);

    if (GST_VIDEO_INFO_FORMAT (&frame->info) !=
        GST_VIDEO_INFO_FORMAT (&cpad->conversion_info)
        || g_strcmp0 (colorimetry, wanted_colorimetry)
        || g_strcmp0 (chroma, wanted_chroma)
        || width != GST_VIDEO_FRAME_WIDTH (frame)
        || height != GST_VIDEO_FRAME_HEIGHT (frame)) {
      GstVideoInfo tmp_info;

      gst_video_info_set_format (&tmp_info, cpad->conversion_info.finfo->format,
          width, height);
      tmp_info.chroma_site = cpad->conversion_info.chroma_site;
      tmp_info.colorimetry = cpad->conversion_info.colorimetry;
      tmp_info.par_n = cpad->conversion_info.par_n;
      tmp_info.par_d = cpad->conversion_info.par_d;
      tmp_info.fps_n = cpad->conversion_info.fps_n;
      tmp_info.fps_d = cpad->conversion_info.fps_d;
      tmp_info.flags = cpad->conversion_info.flags;
      tmp_info.interlace_mode = cpad->conversion_info.interlace_mode;

      GST_DEBUG_OBJECT (pad, "This pad will be converted from %d to %d",
          GST_VIDEO_INFO_FORMAT (&frame->info),
          GST_VIDEO_INFO_FORMAT (&tmp_info));
      cpad->convert = gst_video_converter_new (&frame->info, &tmp_info, NULL);
      cpad->conversion_info = tmp_info;

      if (!cpad->convert) {
        GST_WARNING_OBJECT (pad, "No path found for conversion");
        g_free (colorimetry);
        g_free (wanted_colorimetry);
        gst_video_frame_unmap (frame);
        g_slice_free (GstVideoFrame, frame);
        return FALSE;
      }
    } else {
      cpad->conversion_info.width = width;
      cpad->conversion_info.height = height;
    }

    g_free (colorimetry);
    g_free (wanted_colorimetry);
  }

  if (cpad->convert) {
    gint converted_size;

    converted_frame = g_slice_new0 (GstVideoFrame);

    /* We wait until here to set the conversion infos, in case vagg->info changed */
    converted_size = cpad->conversion_info.size;
    outsize = GST_VIDEO_INFO_SIZE (&vagg->info);
    converted_size = converted_size > outsize ? converted_size : outsize;
    converted_buf = gst_buffer_new_allocate (NULL, converted_size, &params);

    if (!gst_video_frame_map (converted_frame, &(cpad->conversion_info),
            converted_buf, GST_MAP_READWRITE)) {
      GST_WARNING_OBJECT (vagg, "Could not map converted frame");

      g_slice_free (GstVideoFrame, converted_frame);
      gst_video_frame_unmap (frame);
      g_slice_free (GstVideoFrame, frame);
      return FALSE;
    }

    gst_video_converter_frame (cpad->convert, frame, converted_frame);
    cpad->converted_buffer = converted_buf;
    gst_video_frame_unmap (frame);
    g_slice_free (GstVideoFrame, frame);
  } else {
    converted_frame = frame;
  }

  pad->aggregated_frame = converted_frame;

  return TRUE;
}

static void
gst_compositor_pad_clean_frame (GstVideoAggregatorPad * pad,
    GstVideoAggregator * vagg)
{
  GstCompositorPad *cpad = GST_COMPOSITOR_PAD (pad);

  if (pad->aggregated_frame) {
    gst_video_frame_unmap (pad->aggregated_frame);
    g_slice_free (GstVideoFrame, pad->aggregated_frame);
    pad->aggregated_frame = NULL;
  }

  if (cpad->converted_buffer) {
    gst_buffer_unref (cpad->converted_buffer);
    cpad->converted_buffer = NULL;
  }
}

static void
gst_compositor_pad_finalize (GObject * object)
{
  GstCompositorPad *pad = GST_COMPOSITOR_PAD (object);

  if (pad->convert)
    gst_video_converter_free (pad->convert);
  pad->convert = NULL;

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

static void
gst_compositor_pad_class_init (GstCompositorPadClass * klass)
{
  GObjectClass *gobject_class = (GObjectClass *) klass;
  GstVideoAggregatorPadClass *vaggpadclass =
      (GstVideoAggregatorPadClass *) klass;

  gobject_class->set_property = gst_compositor_pad_set_property;
  gobject_class->get_property = gst_compositor_pad_get_property;
  gobject_class->finalize = gst_compositor_pad_finalize;

  g_object_class_install_property (gobject_class, PROP_PAD_XPOS,
      g_param_spec_int ("xpos", "X Position", "X Position of the picture",
          G_MININT, G_MAXINT, DEFAULT_PAD_XPOS,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_PAD_YPOS,
      g_param_spec_int ("ypos", "Y Position", "Y Position of the picture",
          G_MININT, G_MAXINT, DEFAULT_PAD_YPOS,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_PAD_WIDTH,
      g_param_spec_int ("width", "Width", "Width of the picture",
          G_MININT, G_MAXINT, DEFAULT_PAD_WIDTH,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_PAD_HEIGHT,
      g_param_spec_int ("height", "Height", "Height of the picture",
          G_MININT, G_MAXINT, DEFAULT_PAD_HEIGHT,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_PAD_ALPHA,
      g_param_spec_double ("alpha", "Alpha", "Alpha of the picture", 0.0, 1.0,
          DEFAULT_PAD_ALPHA,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  vaggpadclass->set_info = GST_DEBUG_FUNCPTR (gst_compositor_pad_set_info);
  vaggpadclass->prepare_frame =
      GST_DEBUG_FUNCPTR (gst_compositor_pad_prepare_frame);
  vaggpadclass->clean_frame =
      GST_DEBUG_FUNCPTR (gst_compositor_pad_clean_frame);
}

static void
gst_compositor_pad_init (GstCompositorPad * compo_pad)
{
  compo_pad->xpos = DEFAULT_PAD_XPOS;
  compo_pad->ypos = DEFAULT_PAD_YPOS;
  compo_pad->alpha = DEFAULT_PAD_ALPHA;
}


/* GstCompositor */
#define DEFAULT_BACKGROUND COMPOSITOR_BACKGROUND_CHECKER
enum
{
  PROP_0,
  PROP_BACKGROUND
};

#define GST_TYPE_COMPOSITOR_BACKGROUND (gst_compositor_background_get_type())
static GType
gst_compositor_background_get_type (void)
{
  static GType compositor_background_type = 0;

  static const GEnumValue compositor_background[] = {
    {COMPOSITOR_BACKGROUND_CHECKER, "Checker pattern", "checker"},
    {COMPOSITOR_BACKGROUND_BLACK, "Black", "black"},
    {COMPOSITOR_BACKGROUND_WHITE, "White", "white"},
    {COMPOSITOR_BACKGROUND_TRANSPARENT,
        "Transparent Background to enable further compositing", "transparent"},
    {0, NULL, NULL},
  };

  if (!compositor_background_type) {
    compositor_background_type =
        g_enum_register_static ("GstCompositorBackground",
        compositor_background);
  }
  return compositor_background_type;
}

static void
gst_compositor_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec)
{
  GstCompositor *self = GST_COMPOSITOR (object);

  switch (prop_id) {
    case PROP_BACKGROUND:
      g_value_set_enum (value, self->background);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_compositor_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec)
{
  GstCompositor *self = GST_COMPOSITOR (object);

  switch (prop_id) {
    case PROP_BACKGROUND:
      self->background = g_value_get_enum (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

#define gst_compositor_parent_class parent_class
G_DEFINE_TYPE (GstCompositor, gst_compositor, GST_TYPE_VIDEO_AGGREGATOR);

static gboolean
set_functions (GstCompositor * self, GstVideoInfo * info)
{
  gboolean ret = FALSE;

  self->blend = NULL;
  self->overlay = NULL;
  self->fill_checker = NULL;
  self->fill_color = NULL;

  switch (GST_VIDEO_INFO_FORMAT (info)) {
    case GST_VIDEO_FORMAT_AYUV:
      self->blend = gst_compositor_blend_ayuv;
      self->overlay = gst_compositor_overlay_ayuv;
      self->fill_checker = gst_compositor_fill_checker_ayuv;
      self->fill_color = gst_compositor_fill_color_ayuv;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_ARGB:
      self->blend = gst_compositor_blend_argb;
      self->overlay = gst_compositor_overlay_argb;
      self->fill_checker = gst_compositor_fill_checker_argb;
      self->fill_color = gst_compositor_fill_color_argb;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_BGRA:
      self->blend = gst_compositor_blend_bgra;
      self->overlay = gst_compositor_overlay_bgra;
      self->fill_checker = gst_compositor_fill_checker_bgra;
      self->fill_color = gst_compositor_fill_color_bgra;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_ABGR:
      self->blend = gst_compositor_blend_abgr;
      self->overlay = gst_compositor_overlay_abgr;
      self->fill_checker = gst_compositor_fill_checker_abgr;
      self->fill_color = gst_compositor_fill_color_abgr;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_RGBA:
      self->blend = gst_compositor_blend_rgba;
      self->overlay = gst_compositor_overlay_rgba;
      self->fill_checker = gst_compositor_fill_checker_rgba;
      self->fill_color = gst_compositor_fill_color_rgba;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_Y444:
      self->blend = gst_compositor_blend_y444;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_y444;
      self->fill_color = gst_compositor_fill_color_y444;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_Y42B:
      self->blend = gst_compositor_blend_y42b;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_y42b;
      self->fill_color = gst_compositor_fill_color_y42b;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_YUY2:
      self->blend = gst_compositor_blend_yuy2;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_yuy2;
      self->fill_color = gst_compositor_fill_color_yuy2;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_UYVY:
      self->blend = gst_compositor_blend_uyvy;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_uyvy;
      self->fill_color = gst_compositor_fill_color_uyvy;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_YVYU:
      self->blend = gst_compositor_blend_yvyu;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_yvyu;
      self->fill_color = gst_compositor_fill_color_yvyu;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_I420:
      self->blend = gst_compositor_blend_i420;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_i420;
      self->fill_color = gst_compositor_fill_color_i420;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_YV12:
      self->blend = gst_compositor_blend_yv12;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_yv12;
      self->fill_color = gst_compositor_fill_color_yv12;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_NV12:
      self->blend = gst_compositor_blend_nv12;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_nv12;
      self->fill_color = gst_compositor_fill_color_nv12;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_NV21:
      self->blend = gst_compositor_blend_nv21;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_nv21;
      self->fill_color = gst_compositor_fill_color_nv21;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_Y41B:
      self->blend = gst_compositor_blend_y41b;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_y41b;
      self->fill_color = gst_compositor_fill_color_y41b;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_RGB:
      self->blend = gst_compositor_blend_rgb;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_rgb;
      self->fill_color = gst_compositor_fill_color_rgb;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_BGR:
      self->blend = gst_compositor_blend_bgr;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_bgr;
      self->fill_color = gst_compositor_fill_color_bgr;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_xRGB:
      self->blend = gst_compositor_blend_xrgb;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_xrgb;
      self->fill_color = gst_compositor_fill_color_xrgb;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_xBGR:
      self->blend = gst_compositor_blend_xbgr;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_xbgr;
      self->fill_color = gst_compositor_fill_color_xbgr;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_RGBx:
      self->blend = gst_compositor_blend_rgbx;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_rgbx;
      self->fill_color = gst_compositor_fill_color_rgbx;
      ret = TRUE;
      break;
    case GST_VIDEO_FORMAT_BGRx:
      self->blend = gst_compositor_blend_bgrx;
      self->overlay = self->blend;
      self->fill_checker = gst_compositor_fill_checker_bgrx;
      self->fill_color = gst_compositor_fill_color_bgrx;
      ret = TRUE;
      break;
    default:
      break;
  }

  return ret;
}

static GstCaps *
_update_caps (GstVideoAggregator * vagg, GstCaps * caps)
{
  GList *l;
  gint best_width = -1, best_height = -1;
  GstVideoInfo info;
  GstCaps *ret = NULL;

  gst_video_info_from_caps (&info, caps);

  GST_OBJECT_LOCK (vagg);
  for (l = GST_ELEMENT (vagg)->sinkpads; l; l = l->next) {
    GstVideoAggregatorPad *vaggpad = l->data;
    GstCompositorPad *compositor_pad = GST_COMPOSITOR_PAD (vaggpad);
    gint this_width, this_height;
    gint width, height;

    if (compositor_pad->width > 0)
      width = compositor_pad->width;
    else
      width = GST_VIDEO_INFO_WIDTH (&vaggpad->info);

    if (compositor_pad->height > 0)
      height = compositor_pad->height;
    else
      height = GST_VIDEO_INFO_HEIGHT (&vaggpad->info);

    if (width == 0 || height == 0)
      continue;

    this_width = width + MAX (compositor_pad->xpos, 0);
    this_height = height + MAX (compositor_pad->ypos, 0);

    if (best_width < this_width)
      best_width = this_width;
    if (best_height < this_height)
      best_height = this_height;
  }
  GST_OBJECT_UNLOCK (vagg);

  if (best_width > 0 && best_height > 0) {
    info.width = best_width;
    info.height = best_height;
    if (set_functions (GST_COMPOSITOR (vagg), &info))
      ret = gst_video_info_to_caps (&info);
  }

  return ret;
}

static GstFlowReturn
gst_compositor_aggregate_frames (GstVideoAggregator * vagg, GstBuffer * outbuf)
{
  GList *l;
  GstCompositor *self = GST_COMPOSITOR (vagg);
  BlendFunction composite;
  GstVideoFrame out_frame, *outframe;

  if (!gst_video_frame_map (&out_frame, &vagg->info, outbuf, GST_MAP_WRITE)) {
    GST_WARNING_OBJECT (vagg, "Could not map output buffer");
    return GST_FLOW_ERROR;
  }

  outframe = &out_frame;
  /* default to blending */
  composite = self->blend;
  switch (self->background) {
    case COMPOSITOR_BACKGROUND_CHECKER:
      self->fill_checker (outframe);
      break;
    case COMPOSITOR_BACKGROUND_BLACK:
      self->fill_color (outframe, 16, 128, 128);
      break;
    case COMPOSITOR_BACKGROUND_WHITE:
      self->fill_color (outframe, 240, 128, 128);
      break;
    case COMPOSITOR_BACKGROUND_TRANSPARENT:
    {
      guint i, plane, num_planes, height;

      num_planes = GST_VIDEO_FRAME_N_PLANES (outframe);
      for (plane = 0; plane < num_planes; ++plane) {
        guint8 *pdata;
        gsize rowsize, plane_stride;

        pdata = GST_VIDEO_FRAME_PLANE_DATA (outframe, plane);
        plane_stride = GST_VIDEO_FRAME_PLANE_STRIDE (outframe, plane);
        rowsize = GST_VIDEO_FRAME_COMP_WIDTH (outframe, plane)
            * GST_VIDEO_FRAME_COMP_PSTRIDE (outframe, plane);
        height = GST_VIDEO_FRAME_COMP_HEIGHT (outframe, plane);
        for (i = 0; i < height; ++i) {
          memset (pdata, 0, rowsize);
          pdata += plane_stride;
        }
      }

      /* use overlay to keep background transparent */
      composite = self->overlay;
      break;
    }
  }

  GST_OBJECT_LOCK (vagg);
  for (l = GST_ELEMENT (vagg)->sinkpads; l; l = l->next) {
    GstVideoAggregatorPad *pad = l->data;
    GstCompositorPad *compo_pad = GST_COMPOSITOR_PAD (pad);

    if (pad->aggregated_frame != NULL) {
      composite (pad->aggregated_frame, compo_pad->xpos, compo_pad->ypos,
          compo_pad->alpha, outframe);
    }
  }
  GST_OBJECT_UNLOCK (vagg);

  gst_video_frame_unmap (outframe);

  return GST_FLOW_OK;
}

static gboolean
_sink_query (GstAggregator * agg, GstAggregatorPad * bpad, GstQuery * query)
{
  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_ALLOCATION:{
      GstCaps *caps;
      GstVideoInfo info;
      GstBufferPool *pool;
      guint size;
      GstStructure *structure;

      gst_query_parse_allocation (query, &caps, NULL);

      if (caps == NULL)
        return FALSE;

      if (!gst_video_info_from_caps (&info, caps))
        return FALSE;

      size = GST_VIDEO_INFO_SIZE (&info);

      pool = gst_video_buffer_pool_new ();

      structure = gst_buffer_pool_get_config (pool);
      gst_buffer_pool_config_set_params (structure, caps, size, 0, 0);

      if (!gst_buffer_pool_set_config (pool, structure)) {
        gst_object_unref (pool);
        return FALSE;
      }

      gst_query_add_allocation_pool (query, pool, size, 0, 0);
      gst_object_unref (pool);
      gst_query_add_allocation_meta (query, GST_VIDEO_META_API_TYPE, NULL);

      return TRUE;
    }
    default:
      return GST_AGGREGATOR_CLASS (parent_class)->sink_query (agg, bpad, query);
  }
}

/* GObject boilerplate */
static void
gst_compositor_class_init (GstCompositorClass * klass)
{
  GObjectClass *gobject_class = (GObjectClass *) klass;
  GstElementClass *gstelement_class = (GstElementClass *) klass;
  GstVideoAggregatorClass *videoaggregator_class =
      (GstVideoAggregatorClass *) klass;
  GstAggregatorClass *agg_class = (GstAggregatorClass *) klass;

  gobject_class->get_property = gst_compositor_get_property;
  gobject_class->set_property = gst_compositor_set_property;

  agg_class->sinkpads_type = GST_TYPE_COMPOSITOR_PAD;
  agg_class->sink_query = _sink_query;
  videoaggregator_class->update_caps = _update_caps;
  videoaggregator_class->aggregate_frames = gst_compositor_aggregate_frames;

  g_object_class_install_property (gobject_class, PROP_BACKGROUND,
      g_param_spec_enum ("background", "Background", "Background type",
          GST_TYPE_COMPOSITOR_BACKGROUND,
          DEFAULT_BACKGROUND, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&src_factory));
  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&sink_factory));

  gst_element_class_set_static_metadata (gstelement_class, "Compositor",
      "Filter/Editor/Video/Compositor",
      "Composite multiple video streams", "Wim Taymans <wim@fluendo.com>, "
      "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
}

static void
gst_compositor_init (GstCompositor * self)
{
  self->background = DEFAULT_BACKGROUND;
  /* initialize variables */
}

/* Element registration */
static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (gst_compositor_debug, "compositor", 0, "compositor");

  gst_compositor_init_blend ();

  return gst_element_register (plugin, "compositor", GST_RANK_PRIMARY + 1,
      GST_TYPE_COMPOSITOR);
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    compositor,
    "Compositor", plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME,
    GST_PACKAGE_ORIGIN)