gstreamer example for mp3 player

 

/* playmp3.c */

#include <gst/gst.h>
#include <unistd.h>

void show_version(void);

int main(int argc, char *argv[]) {
	GstElement *pipeline, *filesrc, *decoder, *conv, *audiosink;
	gchar *name;
	GstElementFactory *factory;
	GstState *state;
	gchar *status;
	
	gst_init(&argc, &argv);
	show_version();

	if (argc != 2) {
		g_print("usage: %s <filename>\n", argv[0]);
		return -1;
	}

	/* 创建一条新的管道 */
	pipeline = gst_pipeline_new("pipeline");

	/* 生成用于读取硬盘数据的元件 */
	filesrc = gst_element_factory_make("filesrc", "file-source");
	g_object_set(G_OBJECT(filesrc), "location", argv[1], NULL);
	
	/* get name */
  	g_object_get (G_OBJECT (filesrc), "name", &name, NULL);
  	g_print ("The name of the element is '%s'.\n", name);
  	g_free (name);
  	
  	/* get factory */
  	factory = gst_element_factory_find ("filesrc");
  	if (!factory) {
    	g_print ("You don't have the 'filesrc' element installed!\n");
    	return -1;
  	}
  	
  	/* display information */
  	g_print ("The '%s' element is a member of the category %s.\n"
           "Description: %s\n",
           gst_plugin_feature_get_name (GST_PLUGIN_FEATURE (factory)),
           gst_element_factory_get_klass (factory),
           gst_element_factory_get_description (factory));
	
	/* 创建解码器元件 */
	//	decoder = gst_element_factory_make ("wavparse", "wav-decoder");
	decoder = gst_element_factory_make("mad", "mad-decoder");

	conv = gst_element_factory_make("audioconvert", "converter");

	/* 创建音频回放元件 */
	audiosink = gst_element_factory_make("autoaudiosink", "audio-output");

	if (!pipeline || !filesrc || !decoder || !conv || !audiosink) {
		g_print("One element could not be created\n");
		g_print("%p %p %p %p %p\n", pipeline, filesrc, decoder, conv, audiosink);
		return -1;
	}

	/* 将生成的元件添加到管道中 */
	gst_bin_add_many(GST_BIN(pipeline), filesrc, decoder, conv, audiosink, NULL);

	/* 连接各个元件 */
	if (!gst_element_link_many(filesrc, decoder, conv, audiosink, NULL)) {
		g_warning("Failed to link elements!");
		return -1;
	}

	/* 开始播放 */
	gst_element_set_state(pipeline, GST_STATE_PLAYING);
	
	gst_element_get_state (pipeline, state, NULL, 1000);
		switch (*state) {
			case GST_STATE_VOID_PENDING:
				status = "VOID_PENDING";
				break;
  			case GST_STATE_NULL:
  				status = "NULL";
				break;
  			case GST_STATE_READY:
  				status = "READY";
				break;
  			case GST_STATE_PAUSED:
  				status = "PAUSED";
				break;
  			case GST_STATE_PLAYING:
  				status = "PLAYING";
				break;
			default:
				status = "UNKNOWN";
				break;
		}
		g_print("\rpipeline status: %s", status);
	while (gst_bin_iterate_recurse(GST_BIN(pipeline))) {
		usleep(100);
	}

	gst_element_get_state (pipeline, state, NULL, 1000);
		switch (*state) {
			case GST_STATE_VOID_PENDING:
				status = "VOID_PENDING";
				break;
  			case GST_STATE_NULL:
  				status = "NULL";
				break;
  			case GST_STATE_READY:
  				status = "READY";
				break;
  			case GST_STATE_PAUSED:
  				status = "PAUSED";
				break;
  			case GST_STATE_PLAYING:
  				status = "PLAYING";
				break;
			default:
				status = "UNKNOWN";
				break;
		}
		g_print("\rpipeline status: %s", status);
		
	/* 停止管道处理流程 */
	gst_element_set_state(pipeline, GST_STATE_NULL);

	/* 释放占用的资源 */
	gst_object_unref(GST_OBJECT(pipeline));

	return 0;
}

void show_version(void) {
	const gchar *nano_str;
	guint major, minor, micro, nano;

	gst_version(&major, &minor, &micro, &nano);
	if (nano == 1)
		nano_str = "(CVS)";
	else if (nano == 2)
		nano_s