先贴代码吧：
#include <gst/gst.h>int main(int argc, char *argv[]) {
GstElement *pipeline, *source, *sink;GstBus *bus;GstMessage *msg;GstStateChangeReturn ret;/* Initialize GStreamer */gst_init(&argc, &argv);/* Create the elements */source = gst_element_factory_make("videotestsrc", "source");sink = gst_element_factory_make("autovideosink", "sink");/* Create the empty pipeline */pipeline = gst_pipeline_new("test-pipeline");if (!pipeline || !source || !sink) {
g_printerr("Not all elements could be created.\n");return -1;}/* Build the pipeline */gst_bin_add_many(GST_BIN (pipeline), source, sink, NULL);if (gst_element_link (source, sink) != TRUE) {
g_printerr("Elements could not be linked.\n");gst_object_unref(pipeline);return -1;}/* Modify the source's properties */g_object_set(source, "pattern", 0, NULL);/* Start playing */ret = gst_element_set_state (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(pipeline);return -1;}/* Wait until error or EOS */bus = gst_element_get_bus(pipeline);msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, 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);break;case GST_MESSAGE_EOS:g_print("End-Of-Stream reached.\n");break;default:/* We should not reach here because we only asked for ERRORs and EOS */g_printerr("Unexpected message received.\n");break;}gst_message_unref(msg);}/* Free resources */gst_object_unref(bus);gst_element_set_state(pipeline, GST_STATE_NULL);gst_object_unref(pipeline);return 0;
}
代码精简如下：
// 创建两个基本元素和一个管道source = gst_element_factory_make("videotestsrc", "source");sink = gst_element_factory_make("autovideosink", "sink");pipeline = gst_pipeline_new("test-pipeline");//把两个基本元素放到管道里面gst_bin_add_many(GST_BIN (pipeline), source, sink, NULL);//设置视频源类型g_object_set(source, "pattern", 0, NULL);//开始播放ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);//在窗口显示视频bus = gst_element_get_bus(pipeline);msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
source、sink、pipeline 之间的关系如下：
