diff options
Diffstat (limited to 'tutorials/basic-tutorial-3.c')
| -rw-r--r-- | tutorials/basic-tutorial-3.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/tutorials/basic-tutorial-3.c b/tutorials/basic-tutorial-3.c new file mode 100644 index 0000000..8ec0dca --- /dev/null +++ b/tutorials/basic-tutorial-3.c @@ -0,0 +1,149 @@ +#include <gst/gst.h>
+
+/* Structure to contain all our information, so we can pass it to callbacks */
+typedef struct _CustomData {
+ GstElement *pipeline;
+ GstElement *source;
+ GstElement *convert;
+ GstElement *sink;
+} CustomData;
+
+/* Handler for the pad-added signal */
+static void pad_added_handler (GstElement *src, GstPad *pad, CustomData *data);
+
+int main(int argc, char *argv[]) {
+ CustomData data;
+ GstBus *bus;
+ GstMessage *msg;
+ GstStateChangeReturn ret;
+ gboolean terminate = FALSE;
+
+ /* Initialize GStreamer */
+ gst_init (&argc, &argv);
+
+ /* Create the elements */
+ data.source = gst_element_factory_make ("uridecodebin", "source");
+ data.convert = gst_element_factory_make ("audioconvert", "convert");
+ data.sink = gst_element_factory_make ("autoaudiosink", "sink");
+
+ /* Create the empty pipeline */
+ data.pipeline = gst_pipeline_new ("test-pipeline");
+
+ if (!data.pipeline || !data.source || !data.convert || !data.sink) {
+ g_printerr ("Not all elements could be created.\n");
+ return -1;
+ }
+
+ /* Build the pipeline. Note that we are NOT linking the source at this
+ * point. We will do it later. */
+ gst_bin_add_many (GST_BIN (data.pipeline), data.source, data.convert , data.sink, NULL);
+ if (!gst_element_link (data.convert, data.sink)) {
+ g_printerr ("Elements could not be linked.\n");
+ gst_object_unref (data.pipeline);
+ return -1;
+ }
+
+ /* Set the URI to play */
+ g_object_set (data.source, "uri", "https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm", NULL);
+
+ /* Connect to the pad-added signal */
+ g_signal_connect (data.source, "pad-added", G_CALLBACK (pad_added_handler), &data);
+
+ /* Start playing */
+ ret = gst_element_set_state (data.pipeline, GST_STATE_PLAYING);
+ if (ret == GST_STATE_CHANGE_FAILURE) {
+ g_printerr ("Unable to set the pipeline to the playing state.\n");
+ gst_object_unref (data.pipeline);
+ return -1;
+ }
+
+ /* Listen to the bus */
+ bus = gst_element_get_bus (data.pipeline);
+ do {
+ msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE,
+ GST_MESSAGE_STATE_CHANGED | GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
+
+ /* Parse message */
+ if (msg != NULL) {
+ GError *err;
+ gchar *debug_info;
+
+ switch (GST_MESSAGE_TYPE (msg)) {
+ case GST_MESSAGE_ERROR:
+ gst_message_parse_error (msg, &err, &debug_info);
+ g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
+ g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
+ g_clear_error (&err);
+ g_free (debug_info);
+ terminate = TRUE;
+ break;
+ case GST_MESSAGE_EOS:
+ g_print ("End-Of-Stream reached.\n");
+ terminate = TRUE;
+ break;
+ case GST_MESSAGE_STATE_CHANGED:
+ /* We are only interested in state-changed messages from the pipeline */
+ if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data.pipeline)) {
+ GstState old_state, new_state, pending_state;
+ gst_message_parse_state_changed (msg, &old_state, &new_state, &pending_state);
+ g_print ("Pipeline state changed from %s to %s:\n",
+ gst_element_state_get_name (old_state), gst_element_state_get_name (new_state));
+ }
+ break;
+ default:
+ /* We should not reach here */
+ g_printerr ("Unexpected message received.\n");
+ break;
+ }
+ gst_message_unref (msg);
+ }
+ } while (!terminate);
+
+ /* Free resources */
+ gst_object_unref (bus);
+ gst_element_set_state (data.pipeline, GST_STATE_NULL);
+ gst_object_unref (data.pipeline);
+ return 0;
+}
+
+/* This function will be called by the pad-added signal */
+static void pad_added_handler (GstElement *src, GstPad *new_pad, CustomData *data) {
+ GstPad *sink_pad = gst_element_get_static_pad (data->convert, "sink");
+ GstPadLinkReturn ret;
+ GstCaps *new_pad_caps = NULL;
+ GstStructure *new_pad_struct = NULL;
+ const gchar *new_pad_type = NULL;
+
+ g_print ("Received new pad '%s' from '%s':\n", GST_PAD_NAME (new_pad), GST_ELEMENT_NAME (src));
+
+ /* If our converter is already linked, we have nothing to do here */
+ if (gst_pad_is_linked (sink_pad)) {
+ g_print (" We are already linked. Ignoring.\n");
+ goto exit;
+ }
+
+ /* Check the new pad's type */
+ new_pad_caps = gst_pad_query_caps (new_pad, NULL);
+ new_pad_struct = gst_caps_get_structure (new_pad_caps, 0);
+ new_pad_type = gst_structure_get_name (new_pad_struct);
+ if (!g_str_has_prefix (new_pad_type, "audio/x-raw")) {
+ g_print (" It has type '%s' which is not raw audio. Ignoring.\n", new_pad_type);
+ goto exit;
+ }
+
+ /* Attempt the link */
+ ret = gst_pad_link (new_pad, sink_pad);
+ if (GST_PAD_LINK_FAILED (ret)) {
+ g_print (" Type is '%s' but link failed.\n", new_pad_type);
+ } else {
+ g_print (" Link succeeded (type '%s').\n", new_pad_type);
+ }
+
+exit:
+ /* Unreference the new pad's caps, if we got them */
+ if (new_pad_caps != NULL)
+ gst_caps_unref (new_pad_caps);
+
+ /* Unreference the sink pad */
+ gst_object_unref (sink_pad);
+}
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