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155 lines
5.1 KiB
C
155 lines
5.1 KiB
C
/* GStreamer snapshot example
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* Copyright (C) <2007> Wim Taymans <wim.taymans@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#include <gst/gst.h>
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#include <gdk-pixbuf/gdk-pixbuf.h>
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#include <stdlib.h>
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#define CAPS "video/x-raw,format=RGB,width=160,pixel-aspect-ratio=1/1"
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int
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main (int argc, char *argv[])
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{
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GstElement *pipeline, *sink;
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gint width, height;
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GstSample *sample;
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gchar *descr;
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GError *error = NULL;
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GdkPixbuf *pixbuf;
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gint64 duration, position;
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GstStateChangeReturn ret;
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gboolean res;
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GstMapInfo map;
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gst_init (&argc, &argv);
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if (argc != 2) {
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g_print ("usage: %s <uri>\n Writes snapshot.png in the current directory\n",
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argv[0]);
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exit (-1);
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}
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/* create a new pipeline */
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descr =
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g_strdup_printf ("uridecodebin uri=%s ! videoconvert ! videoscale ! "
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" appsink name=sink caps=\"" CAPS "\"", argv[1]);
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pipeline = gst_parse_launch (descr, &error);
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if (error != NULL) {
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g_print ("could not construct pipeline: %s\n", error->message);
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g_error_free (error);
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exit (-1);
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}
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/* get sink */
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sink = gst_bin_get_by_name (GST_BIN (pipeline), "sink");
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/* set to PAUSED to make the first frame arrive in the sink */
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ret = gst_element_set_state (pipeline, GST_STATE_PAUSED);
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switch (ret) {
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case GST_STATE_CHANGE_FAILURE:
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g_print ("failed to play the file\n");
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exit (-1);
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case GST_STATE_CHANGE_NO_PREROLL:
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/* for live sources, we need to set the pipeline to PLAYING before we can
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* receive a buffer. We don't do that yet */
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g_print ("live sources not supported yet\n");
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exit (-1);
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default:
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break;
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}
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/* This can block for up to 5 seconds. If your machine is really overloaded,
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* it might time out before the pipeline prerolled and we generate an error. A
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* better way is to run a mainloop and catch errors there. */
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ret = gst_element_get_state (pipeline, NULL, NULL, 5 * GST_SECOND);
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if (ret == GST_STATE_CHANGE_FAILURE) {
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g_print ("failed to play the file\n");
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exit (-1);
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}
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/* get the duration */
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gst_element_query_duration (pipeline, GST_FORMAT_TIME, &duration);
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if (duration != -1)
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/* we have a duration, seek to 5% */
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position = duration * 5 / 100;
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else
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/* no duration, seek to 1 second, this could EOS */
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position = 1 * GST_SECOND;
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/* seek to the a position in the file. Most files have a black first frame so
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* by seeking to somewhere else we have a bigger chance of getting something
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* more interesting. An optimisation would be to detect black images and then
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* seek a little more */
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gst_element_seek_simple (pipeline, GST_FORMAT_TIME,
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GST_SEEK_FLAG_KEY_UNIT | GST_SEEK_FLAG_FLUSH, position);
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/* get the preroll buffer from appsink, this block untils appsink really
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* prerolls */
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g_signal_emit_by_name (sink, "pull-preroll", &sample, NULL);
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gst_object_unref (sink);
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/* if we have a buffer now, convert it to a pixbuf. It's possible that we
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* don't have a buffer because we went EOS right away or had an error. */
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if (sample) {
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GstBuffer *buffer;
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GstCaps *caps;
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GstStructure *s;
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/* get the snapshot buffer format now. We set the caps on the appsink so
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* that it can only be an rgb buffer. The only thing we have not specified
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* on the caps is the height, which is dependant on the pixel-aspect-ratio
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* of the source material */
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caps = gst_sample_get_caps (sample);
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if (!caps) {
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g_print ("could not get snapshot format\n");
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exit (-1);
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}
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s = gst_caps_get_structure (caps, 0);
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/* we need to get the final caps on the buffer to get the size */
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res = gst_structure_get_int (s, "width", &width);
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res |= gst_structure_get_int (s, "height", &height);
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if (!res) {
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g_print ("could not get snapshot dimension\n");
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exit (-1);
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}
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/* create pixmap from buffer and save, gstreamer video buffers have a stride
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* that is rounded up to the nearest multiple of 4 */
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buffer = gst_sample_get_buffer (sample);
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gst_buffer_map (buffer, &map, GST_MAP_READ);
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pixbuf = gdk_pixbuf_new_from_data (map.data,
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GDK_COLORSPACE_RGB, FALSE, 8, width, height,
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GST_ROUND_UP_4 (width * 3), NULL, NULL);
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/* save the pixbuf */
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gdk_pixbuf_save (pixbuf, "snapshot.png", "png", &error, NULL);
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gst_buffer_unmap (buffer, &map);
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} else {
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g_print ("could not make snapshot\n");
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}
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/* cleanup and exit */
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gst_element_set_state (pipeline, GST_STATE_NULL);
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gst_object_unref (pipeline);
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exit (0);
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}
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