/* GStreamer snapshot example

 * Copyright (C) <2007> Wim Taymans <wim.taymans@gmail.com>

 *

 * 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.

 */

#include <gst/gst.h>

#include <gdk-pixbuf/gdk-pixbuf.h>

#include <stdlib.h>

#define CAPS "video/x-raw,format=RGB,width=160,pixel-aspect-ratio=1/1"

int

main (int argc, char *argv[])

{

  GstElement *pipeline, *sink;

  gint width, height;

  GstSample *sample;

  gchar *descr;

  GError *error = NULL;

  GdkPixbuf *pixbuf;

  gint64 duration, position;

  GstStateChangeReturn ret;

  gboolean res;

  GstMapInfo map;

  gst_init (&argc, &argv);

  if (argc != 2) {

    g_print ("usage: %s <uri>\n Writes snapshot.png in the current directory\n",

        argv[0]);

    exit (-1);

  }

  /* create a new pipeline */

  descr =

      g_strdup_printf ("uridecodebin uri=%s ! videoconvert ! videoscale ! "

      " appsink name=sink caps=\"" CAPS "\"", argv[1]);

  pipeline = gst_parse_launch (descr, &error);

  if (error != NULL) {

    g_print ("could not construct pipeline: %s\n", error->message);

    g_error_free (error);

    exit (-1);

  }

  /* get sink */

  sink = gst_bin_get_by_name (GST_BIN (pipeline), "sink");

  /* set to PAUSED to make the first frame arrive in the sink */

  ret = gst_element_set_state (pipeline, GST_STATE_PAUSED);

  switch (ret) {

    case GST_STATE_CHANGE_FAILURE:

      g_print ("failed to play the file\n");

      exit (-1);

    case GST_STATE_CHANGE_NO_PREROLL:

      /* for live sources, we need to set the pipeline to PLAYING before we can

       * receive a buffer. We don't do that yet */

      g_print ("live sources not supported yet\n");

      exit (-1);

    default:

      break;

  }

  /* This can block for up to 5 seconds. If your machine is really overloaded,

   * it might time out before the pipeline prerolled and we generate an error. A

   * better way is to run a mainloop and catch errors there. */

  ret = gst_element_get_state (pipeline, NULL, NULL, 5 * GST_SECOND);

  if (ret == GST_STATE_CHANGE_FAILURE) {

    g_print ("failed to play the file\n");

    exit (-1);

  }

  /* get the duration */

  gst_element_query_duration (pipeline, GST_FORMAT_TIME, &duration);

  if (duration != -1)

    /* we have a duration, seek to 5% */

    position = duration * 5 / 100;

  else

    /* no duration, seek to 1 second, this could EOS */

    position = 1 * GST_SECOND;

  /* seek to the a position in the file. Most files have a black first frame so

   * by seeking to somewhere else we have a bigger chance of getting something

   * more interesting. An optimisation would be to detect black images and then

   * seek a little more */

  gst_element_seek_simple (pipeline, GST_FORMAT_TIME,

      GST_SEEK_FLAG_KEY_UNIT | GST_SEEK_FLAG_FLUSH, position);

  /* get the preroll buffer from appsink, this block untils appsink really

   * prerolls */

  g_signal_emit_by_name (sink, "pull-preroll", &sample, NULL);

  gst_object_unref (sink);

  /* if we have a buffer now, convert it to a pixbuf. It's possible that we

   * don't have a buffer because we went EOS right away or had an error. */

  if (sample) {

    GstBuffer *buffer;

    GstCaps *caps;

    GstStructure *s;

    /* get the snapshot buffer format now. We set the caps on the appsink so

     * that it can only be an rgb buffer. The only thing we have not specified

     * on the caps is the height, which is dependant on the pixel-aspect-ratio

     * of the source material */

    caps = gst_sample_get_caps (sample);

    if (!caps) {

      g_print ("could not get snapshot format\n");

      exit (-1);

    }

    s = gst_caps_get_structure (caps, 0);

    /* we need to get the final caps on the buffer to get the size */

    res = gst_structure_get_int (s, "width", &width);

    res |= gst_structure_get_int (s, "height", &height);

    if (!res) {

      g_print ("could not get snapshot dimension\n");

      exit (-1);

    }

    /* create pixmap from buffer and save, gstreamer video buffers have a stride

     * that is rounded up to the nearest multiple of 4 */

    buffer = gst_sample_get_buffer (sample);

    gst_buffer_map (buffer, &map, GST_MAP_READ);

    pixbuf = gdk_pixbuf_new_from_data (map.data,

        GDK_COLORSPACE_RGB, FALSE, 8, width, height,

        GST_ROUND_UP_4 (width * 3), NULL, NULL);

    /* save the pixbuf */

    gdk_pixbuf_save (pixbuf, "snapshot.png", "png", &error, NULL);

    gst_buffer_unmap (buffer, &map);

  } else {

    g_print ("could not make snapshot\n");

  }

  /* cleanup and exit */

  gst_element_set_state (pipeline, GST_STATE_NULL);

  gst_object_unref (pipeline);

  exit (0);

}