gfstreamer mp3 play

mp3-play.c

#include <gst/gst.h>

static gboolean
bus_call(GstBus *bus,
         GstMessage *msg,
         gpointer data) {
    GMainLoop *loop = data;

    switch (GST_MESSAGE_TYPE (msg)) {
        case GST_MESSAGE_EOS:
            g_print("End-of-stream\n");
            g_main_loop_quit(loop);
            break;
        case GST_MESSAGE_ERROR: {
            gchar *debug = NULL;
            GError *err = NULL;

            gst_message_parse_error(msg, &err, &debug);

            g_print("Error: %s\n", err->message);
            g_error_free(err);

            if (debug) {
                g_print("Debug details: %s\n", debug);
                g_free(debug);
            }

            g_main_loop_quit(loop);
            break;
        }
        default:
            g_print("unknown message: %d\n", GST_MESSAGE_TYPE(msg));
            break;
    }

    return TRUE;
}

gint
main(gint argc,
     gchar *argv[]) {
    GstStateChangeReturn ret;
    GstElement *pipeline, *filesrc, *decoder, *filter, *sink;
    GstElement *convert1, *convert2, *resample;
    GMainLoop *loop;
    GstBus *bus;
    guint watch_id;

    /* initialization */
    gst_init(&argc, &argv);
    loop = g_main_loop_new(NULL, FALSE);
    if (argc != 2) {
        g_print("Usage: %s <mp3 filename>\n", argv[0]);
        return 01;
    }

    /* create elements */
    pipeline = gst_pipeline_new("my_pipeline");

    /* watch for messages on the pipeline's bus (note that this will only
     * work like this when a GLib main loop is running) */
    bus = gst_pipeline_get_bus(GST_PIPELINE (pipeline));
    watch_id = gst_bus_add_watch(bus, bus_call, loop);
    gst_object_unref(bus);

    filesrc = gst_element_factory_make("filesrc", "my_filesource");
    decoder = gst_element_factory_make("flump3dec", "my_decoder");

    /* putting an audioconvert element here to convert the output of the
     * decoder into a format that my_filter can handle (we are assuming it
     * will handle any sample rate here though) */
    convert1 = gst_element_factory_make("audioconvert", "audioconvert1");

    /* use "identity" here for a filter that does nothing */
    filter = gst_element_factory_make("identity", "my_filter");

    /* there should always be audioconvert and audioresample elements before
     * the audio sink, since the capabilities of the audio sink usually vary
     * depending on the environment (output used, sound card, driver etc.) */
    convert2 = gst_element_factory_make("audioconvert", "audioconvert2");
    resample = gst_element_factory_make("audioresample", "audioresample");
    sink = gst_element_factory_make("autoaudiosink", "audiosink");

    if (!sink || !decoder) {
        if (!sink)
            g_print("Output could not be found\n");
        if (!decoder)
            g_print("Decoder could not be found\n");
        g_print("Decoder or output could not be found - check your install\n");
        return -1;
    } else if (!convert1 || !convert2 || !resample) {
        g_print("Could not create audioconvert or audioresample element, "
                        "check your installation\n");
        return -1;
    } else if (!filter) {
        g_print("Your self-written filter could not be found. Make sure it "
                        "is installed correctly in $(libdir)/gstreamer-1.0/ or "
                        "~/.gstreamer-1.0/plugins/ and that gst-inspect-1.0 lists it. "
                        "If it doesn't, check with 'GST_DEBUG=*:2 gst-inspect-1.0' for "
                        "the reason why it is not being loaded.");
        return -1;
    }

    g_object_set(G_OBJECT (filesrc), "location", argv[1], NULL);

    gst_bin_add_many(GST_BIN (pipeline), filesrc, decoder, sink, NULL);
//    gst_bin_add_many(GST_BIN (pipeline), filesrc, decoder, convert1, filter,
//                     convert2, resample, sink, NULL);

    /* link everything together */
    if (!gst_element_link_many(filesrc, decoder, sink, NULL)) {
//    if (!gst_element_link_many(filesrc, decoder, convert1, filter, convert2,
//                               resample, sink, NULL)) {
        g_print("Failed to link one or more elements!\n");
        return -1;
    }

    /* run */
    ret = gst_element_set_state(pipeline, GST_STATE_PLAYING);
    if (ret == GST_STATE_CHANGE_FAILURE) {
        GstMessage *msg;

        g_print("Failed to start up pipeline!\n");

        /* check if there is an error message with details on the bus */
        msg = gst_bus_poll(bus, GST_MESSAGE_ERROR, 0);
        if (msg) {
            GError *err = NULL;

            gst_message_parse_error(msg, &err, NULL);
            g_print("ERROR: %s\n", err->message);
            g_error_free(err);
            gst_message_unref(msg);
        }
        return -1;
    }

    g_main_loop_run(loop);

    /* clean up */
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);
    g_source_remove(watch_id);
    g_main_loop_unref(loop);

    return 0;
}