overlaycomposition

The overlaycomposition element renders an overlay using an application provided draw function.

Example code

#include <gst/gst.h>
#include <gst/video/video.h>

#include <math.h>

#include <gio/gio.h>
#include <stdlib.h>

#define VIDEO_WIDTH 720
#define VIDEO_HEIGHT 480
#define VIDEO_FPS 50

/* GdkPixbuf RGBA C-Source image dump from gdk-pixbuf-csource --raw,
 * gzipped and then base64 encoded */
const gchar gzipped_pixdata_base64[] =
    "H4sICPX/Z1QAA2xvZ28ucGl4AO2dsZHrNhCG+ewK2II64ClyrhmnTtSBh4kLUOLQAUuwEhSgFtiA"
    "A7agwA2wBT5AXJ5w4P5LgKLEO97ezDf2SCAIAftjFwuQ7/c///ojy/77+8eP7Jcs+/WfLMv+t/zW"
    "dV32pSmK3HK6sXZbFOXV9PZfWipLbWksHdHQZxVpZP+Ee7u62/d7rt0fivIqimJnOX+w/zhauq68"
    "aWjevfdUR1h3vXq/KMqzufueFN1J1FE+stf8KfCzobZ3q/ePojyT3v8gDSyB09GFND7g/N014rpl"
    "41xF+Wz0/i817nwFjepP+Rb0PnDwOUOehePyQq1eurlrSkXZOkVx7OblbGK43upf+zcqyldhOT22"
    "5GvV9ynKXIriQDpKye242Ldcve2KskX6deaRWVeebnpdu32Koryc4t/iaKksmm9Vvg3W3neWk+Vs"
    "qS2tpSOu9NmZtLG4f7R15paS7jXct1q7XxTl2ZDd157dp1A/6q9I+1Wg+QH1g8pmcb7M0szUHseV"
    "/KTTtJg39XyudH/NASmbhfzOUtqTNHmhew1cglhT9ad8O16kv7m4eFT3/pVNQ77IX8shLgW/RnsW"
    "Li7V5y4UJaDo9wnOT9Sjq1fzn4oSQXHft4tZ00Vpr5jI3yiKwmO1sy/63GZKzNpS+dVyLsaYneVk"
    "Ud+rbIqi32M/kC7DtaXzn6vt9Vm95ZbS0lg64rx2nynKdyHQ3oC+A06ZxdtbkztWundpqS1fKo5j"
    "9OfQ8+jKJNbW987eye47QGO5WE6u/BPakJP2rt4927X7JhanNaBBzQUpEMbmU2hJk66O2ftt7lrS"
    "f8vc4yl+0P7llspyWapOl3th9Hdde4yVz4m17eMD2pP8ZBXjI0l3J7oG1Rf1DlH7dyBOpKuB2+dB"
    "2ZzKXS3ugw9+lnKZB49oH2bL1owGH9K4vX5P7Yg+0+O1/Uj/XSRm8ep9Ws6LclrRfe+N1+xYIxjz"
    "49Jrh6D+m68inSypPeQja7pXRZp3/z1P6M7XM+xX+7eznElHc3E63Hv2xWmoo89H4yLEnpDg+orq"
    "DsnJFq7oWqYtLhd7sbTg3i3dL2VO2Xlt5Oo7DzY1Uc8VtOng9eMZtP0ctpnmJa787Tcm/jbUtmHc"
    "xfmG+p0bwz0R9t1hYr33WTgj/ZEfe1R7HfnJ3NNCjIbKoP8f1SBn2w2Nq3htYI9o7uBopnRI9nmO"
    "rM/ZveijhWulee+DFrx2xZSHe0Gmn99ix5sd96A+1E97w88pB8bX1ABubfYK4DxG+msYPbWWksqU"
    "gu5a0u/O68PQ3t99hWF8kW9vC2gQaWTyWtD2sB5UVzOhGeRLJR2y/pB0k9RHgCqxXaP2kP5Qn9TU"
    "n+He7rumwO/j5oSr0FanQZf/jIp33+650qXXjSj2FP2+y58AbYVrPs5PjuyOxsTvq5H+yYb8Mofg"
    "u8rgmKb2vq/C+lPtMLj2KOjBbyPSqTS3N9T2Y/D5SbAtdt1r4uapoZ9ife+VroHzlQn2ZCf0dw7K"
    "7rk2Cn2VMo6z15pP1KPzt5N72LT+4/Q36hv7d+R8INN/oR2zdunZEcyvANuEPj3SNlkNmvHcIY6x"
    "4eeHWbkiSfugvBT3jeLYifKdCdaHggbC+Q7Vi+YOriznW5PG8BENAj3G5FYQTsslWvcxuqqABke6"
    "oXzoqGyEfcC1kunnXRRvcfOm2N9mOo4szX1df/DnB4P9BbsOMmANNXf8F9TgaB1p5LlppBehfr+/"
    "0PiwuhJ+Y+hbpXpbGsNbLtTcc66LPzP31u+rDznPesJPDnnS5Ny2oMGRnSdoEOVERjpE2qTvTmAc"
    "pGuQ7Yg5EyP7QDY3gjQozREzNIhiNXTv1Ni1BeOCyvvxOJqzUJtzUD6MWaX1wKd4P9HbgmfdhFwL"
    "p0FOr9x6EOngmtKHpt8TGNUxcQ2yTXGeNLL/lHz4Qxo09/0tNN8gH4zainIcyK7ZuF7Q4D6iDal1"
    "1kE5ZD+bfD+DsB48BuXy7L7//mEvgulrKWd3iyUi7ZPzS+J6C1wz+XyFkfMWB0D02tHrl2FfMDYX"
    "yfUvitXg2QvBrlHMyM4JEW3oqC+5/orymwbEUWtr5ck65PKidVCGy4leh71AZgwlv9JN6VDQsZSP"
    "QddM+iUw7nM5BHWn7jWKbRf6VsrJcjEFtGug2dr7HvntOYQa5OanTT8jY//2tMcXauxCuVBOo+9n"
    "YYRxnNIhvN7g2AnGI+iamD4w6bnwqN810QctaUM6V8LlDJFPk9a7qfllzmdVEW2Yg18vmkc/xTrw"
    "yTqU9uDD/fgK+b9EHcK1nTDGcF0Hrok6Gyu00c33KBZlifztYY6fPbcG2poUqwl2LeWXuXv4OVEp"
    "95XUX/6Yoj5bWx8v0F8OfN3g72rS3TFWewk6RHuHXOwkjoXhfVnsOcdFc5xUJ/Jto7gKlEX5xUlN"
    "x/T/RNvFvhA0GDXnCfedPY9+ZUhjvu4Wfy5P0CHKoXGaEMci1TYj7sfqJbI+uBfwSNuFelPPXkp+"
    "k823BGXQWuGh3AmYRzf9zpKMOfvyYB8uEiuC8ZXO00zuZ020G83rs8Y/xU8gmwcaRPVKa+uk/LLh"
    "8y1NUEbKfc+aww3eP/xS73xIBez5XbKPzwuW3H4h6Ec3j6E9ba6PkR9MGgvBNmPbLeXa58TfKRqM"
    "brtJPJuTom/vGm4dwJ2lQXmsWe/cM4l7mFtBOCcjPR+B9iMGW4LnGWLHa4bdzNqbj6wj2QYEXYX+"
    "JPWMKlcOvpdEaIcUu0blUA1eX7Bnbx7os02/N4iLRSMY7QuacWwSc24YjhXQgxQ/sT4s0QbQs2kO"
    "dl1o+hiYs09p/8x/7kPaqw/3GZGfkPbmka9C5wiQ30RzJdp3R2cTh3MKozk6ta1bgfYGUzU42sMX"
    "xsP1q4ttuLxfci7Ps18/RwfPI6f2x4QOG087/m8arRlN2vN9yP+G5yiTcpETbUBxCpo7kGZzof3D"
    "OwGG56ca7/NwDkdrwc1qUNiXT4Hrx9hn1WLOj0n7wDF7Vcka9Gw39lyL9Gz51P78ebAv1G9BfWiv"
    "A2kQ+mKhzbP2aEz8s8DsmWGDfbxjc/+OENDfib4b3uNUejmZqGd8g/5EY3k1CWt2cz9nONR380XM"
    "+HPvHlnivU/ce19aA96FA/TsP2984q6jcpeg/f75kTyoxwfFiSW6ZkJLHDHvt8np93Hv3xliCLT2"
    "OIEx3OTeILMf2EztCYKYNcYG2fMQivKdYbQUpY1s/M6ZTcbpivJMMv5Zpdhn7mdpV1GUO1l/NjTU"
    "Usx7Z8Iz3ZuM0xXlFWT8s4CsDkmzJZPD0ThUUWaSye8THZ6RqOj/uf2L1f79T0XZCpn8vJJ0Pkb9"
    "n6IsCOVoBp/HvS+moe83+T4dRVEUZRmyn2F9swl9yAAA";

static GstBuffer *logo_buf;

static GMainLoop *main_loop;
static gint count;

static GstBuffer *
create_overlay_buffer (void)
{
  GZlibDecompressor *decompress;
  GConverterResult decomp_res;
  guchar *gzipped_pixdata, *pixdata;
  gsize gzipped_size, bytes_read, pixdata_size;
  GstBuffer *logo_pixels;
  guint w, h, stride;

  gzipped_pixdata = g_base64_decode (gzipped_pixdata_base64, &gzipped_size);
  g_assert (gzipped_pixdata != NULL);

  pixdata = g_malloc (64 * 1024);

  decompress = g_zlib_decompressor_new (G_ZLIB_COMPRESSOR_FORMAT_GZIP);
  decomp_res = g_converter_convert (G_CONVERTER (decompress),
      gzipped_pixdata, gzipped_size, pixdata, 64 * 1024,
      G_CONVERTER_INPUT_AT_END, &bytes_read, &pixdata_size, NULL);
  g_assert (decomp_res == G_CONVERTER_FINISHED);
  g_assert (bytes_read == gzipped_size);
  g_free (gzipped_pixdata);
  g_object_unref (decompress);

  /* 0: Pixbuf magic (0x47646b50) */
  g_assert (GST_READ_UINT32_BE (pixdata) == 0x47646b50);

  /* 4: length incl. header */
  /* 8: pixdata_type */
  /* 12: rowstride (900) */
  stride = GST_READ_UINT32_BE (pixdata + 12);
  /* 16: width (225) */
  w = GST_READ_UINT32_BE (pixdata + 16);
  /* 20: height (57) */
  h = GST_READ_UINT32_BE (pixdata + 20);
  /* 24: pixel_data */
  GST_LOG ("%dx%d @ %d", w, h, stride);
  /* we assume that the last line also has padding at the end */
  g_assert (pixdata_size - 24 >= h * stride);

  logo_pixels = gst_buffer_new_and_alloc (h * stride);
  gst_buffer_fill (logo_pixels, 0, pixdata + 24, h * stride);
  gst_buffer_add_video_meta (logo_pixels, GST_VIDEO_FRAME_FLAG_NONE,
      GST_VIDEO_OVERLAY_COMPOSITION_FORMAT_RGB, w, h);

  g_free (pixdata);

  return logo_pixels;
}

static gboolean
message_cb (GstBus * bus, GstMessage * message, gpointer user_data)
{
  switch (GST_MESSAGE_TYPE (message)) {
    case GST_MESSAGE_ERROR:{
      GError *err = NULL;
      gchar *name, *debug = NULL;

      name = gst_object_get_path_string (message->src);
      gst_message_parse_error (message, &err, &debug);

      g_printerr ("ERROR: from element %s: %s\n", name, err->message);
      if (debug != NULL)
        g_printerr ("Additional debug info:\n%s\n", debug);

      g_error_free (err);
      g_free (debug);
      g_free (name);

      g_main_loop_quit (main_loop);
      break;
    }
    case GST_MESSAGE_WARNING:{
      GError *err = NULL;
      gchar *name, *debug = NULL;

      name = gst_object_get_path_string (message->src);
      gst_message_parse_warning (message, &err, &debug);

      g_printerr ("ERROR: from element %s: %s\n", name, err->message);
      if (debug != NULL)
        g_printerr ("Additional debug info:\n%s\n", debug);

      g_error_free (err);
      g_free (debug);
      g_free (name);
      break;
    }
    case GST_MESSAGE_EOS:
      g_print ("Got EOS\n");
      g_main_loop_quit (main_loop);
      break;
    default:
      break;
  }

  return TRUE;
}

typedef struct
{
  gboolean valid;
  GstVideoInfo info;
} OverlayState;

static void
prepare_overlay (GstElement * overlay, GstCaps * caps, gint window_width,
    gint window_height, gpointer user_data)
{
  OverlayState *s = (OverlayState *) user_data;

  if (gst_video_info_from_caps (&s->info, caps))
    s->valid = TRUE;
  else
    s->valid = FALSE;
}

#define SPEED_SCALE_FACTOR (VIDEO_FPS * 4)

/* nicked from videotestsrc's ball pattern renderer */
static void
calculate_position (gint * x, gint * y, guint logo_w, guint logo_h, guint n)
{
  guint r_x = logo_w / 2;
  guint r_y = logo_h / 2;
  guint w = VIDEO_WIDTH + logo_w;
  guint h = VIDEO_HEIGHT + logo_h;

  *x = r_x + (0.5 + 0.5 * sin (2 * G_PI * n / SPEED_SCALE_FACTOR))
      * (w - 2 * r_x);
  *y = r_y + (0.5 + 0.5 * sin (2 * G_PI * sqrt (2) * n / SPEED_SCALE_FACTOR))
      * (h - 2 * r_y);

  *x -= logo_w;
  *y -= logo_h;
}

static GstVideoOverlayComposition *
draw_overlay (GstElement * overlay, GstSample * sample, gpointer user_data)
{
  OverlayState *s = (OverlayState *) user_data;
  GstVideoOverlayRectangle *rect;
  GstVideoOverlayComposition *comp;
  GstVideoMeta *vmeta;
  gint x, y;

  if (!s->valid)
    return NULL;

  vmeta = gst_buffer_get_video_meta (logo_buf);
  calculate_position (&x, &y, vmeta->width, vmeta->height, ++count);

  rect = gst_video_overlay_rectangle_new_raw (logo_buf, x, y,
      vmeta->width, vmeta->height, GST_VIDEO_OVERLAY_FORMAT_FLAG_NONE);
  comp = gst_video_overlay_composition_new (rect);
  gst_video_overlay_rectangle_unref (rect);

  return comp;
}

int
main (int argc, char **argv)
{
  GstElement *pipeline;
  GstElement *src, *capsfilter, *overlay, *conv, *sink;
  GstBus *bus;
  GstCaps *filter_caps;
  OverlayState overlay_state = { 0, };
  GOptionContext *option_ctx;
  GError *error = NULL;
  gchar *video_sink = NULL;
  gboolean ret;
  GOptionEntry options[] = {
    {"videosink", 0, 0, G_OPTION_ARG_STRING, &video_sink,
        "Video sink element to use (default is autovideosink)", NULL},
    {NULL}
  };

  option_ctx = g_option_context_new ("- test overlaycomposition");
  g_option_context_add_main_entries (option_ctx, options, NULL);
  g_option_context_add_group (option_ctx, gst_init_get_option_group ());
  ret = g_option_context_parse (option_ctx, &argc, &argv, &error);
  g_option_context_free (option_ctx);

  if (!ret) {
    g_printerr ("option parsing failed: %s\n", error->message);
    g_clear_error (&error);
    exit (1);
  }

  pipeline = gst_pipeline_new (NULL);
  src = gst_element_factory_make ("videotestsrc", NULL);
  capsfilter = gst_element_factory_make ("capsfilter", NULL);
  overlay = gst_element_factory_make ("overlaycomposition", NULL);
  conv = gst_element_factory_make ("videoconvert", NULL);

  if (!video_sink)
    video_sink = g_strdup ("autovideosink");

  sink = gst_element_factory_make (video_sink, NULL);
  g_free (video_sink);

  if (!pipeline || !src || !capsfilter || !overlay || !conv || !sink) {
    g_error ("Failed to create elements");
    return -1;
  }

  gst_bin_add_many (GST_BIN (pipeline), src, capsfilter, overlay, conv, sink,
      NULL);
  if (!gst_element_link_many (src, capsfilter, overlay, conv, sink, NULL)) {
    g_error ("Failed to link elements");
    return -2;
  }

  filter_caps = gst_caps_from_string ("video/x-raw, format = "
      GST_VIDEO_OVERLAY_COMPOSITION_BLEND_FORMATS);
  gst_caps_set_simple (filter_caps,
      "width", G_TYPE_INT, VIDEO_WIDTH,
      "height", G_TYPE_INT, VIDEO_HEIGHT,
      "framerate", GST_TYPE_FRACTION, VIDEO_FPS, 1, NULL);
  g_object_set (capsfilter, "caps", filter_caps, NULL);
  gst_caps_unref (filter_caps);

  g_signal_connect (overlay, "draw", G_CALLBACK (draw_overlay), &overlay_state);
  g_signal_connect (overlay, "caps-changed",
      G_CALLBACK (prepare_overlay), &overlay_state);


Hierarchy

GObject
    ╰──GInitiallyUnowned
        ╰──GstObject
            ╰──GstElement
                ╰──overlaycomposition

Factory details

Authors: – Sebastian Dröge

Classification:Filter/Editor/Video

Rank – none

Plugin – overlaycomposition

Package – GStreamer Base Plug-ins

Pad Templates

sink

video/x-raw:
         format: { AYUV64, ARGB64, GBRA_12LE, GBRA_12BE, Y412_LE, Y412_BE, A444_10LE, GBRA_10LE, A444_10BE, GBRA_10BE, A422_10LE, A422_10BE, A420_10LE, A420_10BE, RGB10A2_LE, BGR10A2_LE, Y410, GBRA, ABGR, VUYA, BGRA, AYUV, ARGB, RGBA, A420, Y444_16LE, Y444_16BE, v216, P016_LE, P016_BE, Y444_12LE, GBR_12LE, Y444_12BE, GBR_12BE, I422_12LE, I422_12BE, Y212_LE, Y212_BE, I420_12LE, I420_12BE, P012_LE, P012_BE, Y444_10LE, GBR_10LE, Y444_10BE, GBR_10BE, r210, I422_10LE, I422_10BE, NV16_10LE32, Y210, v210, UYVP, I420_10LE, I420_10BE, P010_10LE, NV12_10LE32, NV12_10LE40, P010_10BE, Y444, GBR, NV24, xBGR, BGRx, xRGB, RGBx, BGR, IYU2, v308, RGB, Y42B, NV61, NV16, VYUY, UYVY, YVYU, YUY2, I420, YV12, NV21, NV12, NV12_64Z32, NV12_4L4, NV12_32L32, Y41B, IYU1, YVU9, YUV9, RGB16, BGR16, RGB15, BGR15, RGB8P, GRAY16_LE, GRAY16_BE, GRAY10_LE32, GRAY8 }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

video/x-raw(ANY):
         format: { AYUV64, ARGB64, GBRA_12LE, GBRA_12BE, Y412_LE, Y412_BE, A444_10LE, GBRA_10LE, A444_10BE, GBRA_10BE, A422_10LE, A422_10BE, A420_10LE, A420_10BE, RGB10A2_LE, BGR10A2_LE, Y410, GBRA, ABGR, VUYA, BGRA, AYUV, ARGB, RGBA, A420, Y444_16LE, Y444_16BE, v216, P016_LE, P016_BE, Y444_12LE, GBR_12LE, Y444_12BE, GBR_12BE, I422_12LE, I422_12BE, Y212_LE, Y212_BE, I420_12LE, I420_12BE, P012_LE, P012_BE, Y444_10LE, GBR_10LE, Y444_10BE, GBR_10BE, r210, I422_10LE, I422_10BE, NV16_10LE32, Y210, v210, UYVP, I420_10LE, I420_10BE, P010_10LE, NV12_10LE32, NV12_10LE40, P010_10BE, Y444, GBR, NV24, xBGR, BGRx, xRGB, RGBx, BGR, IYU2, v308, RGB, Y42B, NV61, NV16, VYUY, UYVY, YVYU, YUY2, I420, YV12, NV21, NV12, NV12_64Z32, NV12_4L4, NV12_32L32, Y41B, IYU1, YVU9, YUV9, RGB16, BGR16, RGB15, BGR15, RGB8P, GRAY16_LE, GRAY16_BE, GRAY10_LE32, GRAY8 }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

Presencealways

Directionsink

Object typeGstPad


src

video/x-raw:
         format: { AYUV64, ARGB64, GBRA_12LE, GBRA_12BE, Y412_LE, Y412_BE, A444_10LE, GBRA_10LE, A444_10BE, GBRA_10BE, A422_10LE, A422_10BE, A420_10LE, A420_10BE, RGB10A2_LE, BGR10A2_LE, Y410, GBRA, ABGR, VUYA, BGRA, AYUV, ARGB, RGBA, A420, Y444_16LE, Y444_16BE, v216, P016_LE, P016_BE, Y444_12LE, GBR_12LE, Y444_12BE, GBR_12BE, I422_12LE, I422_12BE, Y212_LE, Y212_BE, I420_12LE, I420_12BE, P012_LE, P012_BE, Y444_10LE, GBR_10LE, Y444_10BE, GBR_10BE, r210, I422_10LE, I422_10BE, NV16_10LE32, Y210, v210, UYVP, I420_10LE, I420_10BE, P010_10LE, NV12_10LE32, NV12_10LE40, P010_10BE, Y444, GBR, NV24, xBGR, BGRx, xRGB, RGBx, BGR, IYU2, v308, RGB, Y42B, NV61, NV16, VYUY, UYVY, YVYU, YUY2, I420, YV12, NV21, NV12, NV12_64Z32, NV12_4L4, NV12_32L32, Y41B, IYU1, YVU9, YUV9, RGB16, BGR16, RGB15, BGR15, RGB8P, GRAY16_LE, GRAY16_BE, GRAY10_LE32, GRAY8 }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

video/x-raw(ANY):
         format: { AYUV64, ARGB64, GBRA_12LE, GBRA_12BE, Y412_LE, Y412_BE, A444_10LE, GBRA_10LE, A444_10BE, GBRA_10BE, A422_10LE, A422_10BE, A420_10LE, A420_10BE, RGB10A2_LE, BGR10A2_LE, Y410, GBRA, ABGR, VUYA, BGRA, AYUV, ARGB, RGBA, A420, Y444_16LE, Y444_16BE, v216, P016_LE, P016_BE, Y444_12LE, GBR_12LE, Y444_12BE, GBR_12BE, I422_12LE, I422_12BE, Y212_LE, Y212_BE, I420_12LE, I420_12BE, P012_LE, P012_BE, Y444_10LE, GBR_10LE, Y444_10BE, GBR_10BE, r210, I422_10LE, I422_10BE, NV16_10LE32, Y210, v210, UYVP, I420_10LE, I420_10BE, P010_10LE, NV12_10LE32, NV12_10LE40, P010_10BE, Y444, GBR, NV24, xBGR, BGRx, xRGB, RGBx, BGR, IYU2, v308, RGB, Y42B, NV61, NV16, VYUY, UYVY, YVYU, YUY2, I420, YV12, NV21, NV12, NV12_64Z32, NV12_4L4, NV12_32L32, Y41B, IYU1, YVU9, YUV9, RGB16, BGR16, RGB15, BGR15, RGB8P, GRAY16_LE, GRAY16_BE, GRAY10_LE32, GRAY8 }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

Presencealways

Directionsrc

Object typeGstPad


Signals

caps-changed

caps_changed_callback (GstElement * overlay,
                       GstCaps * caps,
                       guint window_width,
                       guint window_height,
                       gpointer udata)
def caps_changed_callback (overlay, caps, window_width, window_height, udata):
    #python callback for the 'caps-changed' signal
function caps_changed_callback(overlay: GstElement * overlay, caps: GstCaps * caps, window_width: guint window_width, window_height: guint window_height, udata: gpointer udata): {
    // javascript callback for the 'caps-changed' signal
}

This signal is emitted when the caps of the element has changed.

The window width and height define the resolution at which the frame is going to be rendered in the end by e.g. a video sink (i.e. the window size).

Parameters:

overlay

Overlay element emitting the signal.

caps

The GstCaps of the element.

window_width

The window render width of downstream, or 0.

window_height

The window render height of downstream, or 0.

udata
No description available

Flags:


draw

GstVideoOverlayComposition *
draw_callback (GstElement * overlay,
               GstSample * sample,
               gpointer udata)
def draw_callback (overlay, sample, udata):
    #python callback for the 'draw' signal
function draw_callback(overlay: GstElement * overlay, sample: GstSample * sample, udata: gpointer udata): {
    // javascript callback for the 'draw' signal
}

This signal is emitted when the overlay should be drawn.

Parameters:

overlay

Overlay element emitting the signal.

sample

GstSample containing the current buffer, caps and segment.

udata
No description available

Flags:


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