| |
| /*** block from ../../../docs/manual/advanced-dataaccess.xml ***/ |
| #include <gst/gst.h> |
| #ifdef HAVE_GTK |
| #include <gtk/gtk.h> |
| #endif |
| |
| #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; |
| 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); |
| |
| /* 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); |
| #ifdef HAVE_GTK |
| 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); |
| #endif |
| gst_buffer_unmap (buffer, &map); |
| gst_sample_unref (sample); |
| } 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); |
| } |