使用gstreamer1.16.3API在代码里如何提取 给个示例

以下是一个使用GStreamer 1.16.3 API提取H.264流中的SPS和PPS的示例：

#include <gst/gst.h>

int main(int argc, char *argv[]) {
    GstElement *pipeline, *src, *h264parse, *sink;
    GstCaps *caps;
    GstBus *bus;
    GstMessage *msg;
    GMainLoop *loop;

    /* Initialize GStreamer */
    gst_init(&argc, &argv);

    /* Create the elements */
    pipeline = gst_pipeline_new("mypipeline");
    src = gst_element_factory_make("filesrc", "mysrc");
    h264parse = gst_element_factory_make("h264parse", "myh264parse");
    sink = gst_element_factory_make("fakesink", "mysink");

    /* Set the input file location */
    g_object_set(G_OBJECT(src), "location", "test.h264", NULL);

    /* Set the caps for h264parse element */
    caps = gst_caps_new_simple("video/x-h264",
                               "stream-format", G_TYPE_STRING, "byte-stream",
                               NULL);
    g_object_set(G_OBJECT(h264parse), "caps", caps, NULL);
    gst_caps_unref(caps);

    /* Add elements to the pipeline */
    gst_bin_add_many(GST_BIN(pipeline), src, h264parse, sink, NULL);

    /* Link the elements */
    if (!gst_element_link_many(src, h264parse, sink, NULL)) {
        g_printerr("Failed to link elements\n");
        return -1;
    }

    /* Start playing the pipeline */
    gst_element_set_state(pipeline, GST_STATE_PLAYING);

    /* Wait for the pipeline to finish or an error to occur */
    loop = g_main_loop_new(NULL, FALSE);
    bus = gst_element_get_bus(pipeline);
    msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE,
                                     GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
    if (msg != NULL) {
        gst_message_unref(msg);
    }
    gst_object_unref(bus);
    g_main_loop_unref(loop);

    /* Stop and cleanup the pipeline */
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);

    return 0;
}

在上面的代码中，我们创建了一个GStreamer管道，其中包含了filesrc、h264parse和fakesink三个元素。我们设置了filesrc的输入文件位置，设置了h264parse的caps，然后将所有元素链接在一起。最后，我们启动了管道，并等待它结束或出现错误。在程序结束时，我们停止和清除了管道。

请注意，上述代码中的"h264parse"元素是通过gst_element_factory_make()函数来创建的，这意味着你的GStreamer库必须包含h264parse插件。如果你的库中没有h264parse插件，你需要先安装它。