使用gstreamer,rtsp拉流，保存图像， jeston，使用硬件加速nvdec/nvenc

jeston，拉流，使用硬件加速nvdec/nvenc

#include 
 
/* Structure to contain all our information, so we can pass it to callbacks */
typedef struct _CustomData {
    GstElement *pipeline;
    GstElement *source;
    GstElement *depay;
    GstElement *parse;
    GstElement *avdec;
    GstElement *convert;
    GstElement *encoder;
    GstElement *sink;
    // GstElement *pipeline, *source, *depay, *parse, *avdec, *convert, *encoder, *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 
      videotestsrc 是一个源元素（它生成数据），用于创建测试视频模式。
      此元素对于调试目的（和教程）非常有用，通常在实际应用程序中找不到。
      autovideosink是一个接收器元素（它消耗数据），在窗口上显示它接收的图像。
    */
    data.source = gst_element_factory_make ("rtspsrc", "source");
    g_object_set (G_OBJECT (data.source), "latency", 2000, NULL);
    data.depay = gst_element_factory_make ("rtph264depay", "depay");
    data.parse = gst_element_factory_make ("h264parse", "parse");
    data.avdec = gst_element_factory_make ("nvv4l2decoder", "decoder");
    data.convert = gst_element_factory_make ("nvvidconv", "convert");
    // nv4l2h264enc、nv4l2vp9enc和nvjpegenc
    // data.encoder = gst_element_factory_make("nvv4l2h264enc", "encoder");
    // data.encoder = gst_element_factory_make("jpegenc", "encoder");
    // data.encoder = gst_element_factory_make("omxh264enc", "encoder");
    // data.encoder = gst_element_factory_make("nvjpegenc", "encoder");

    data.encoder = gst_element_factory_make("nvv4l2h264enc", "encoder");

    data.sink = gst_element_factory_make ("multifilesink", "sink");
 
 
    /* Modify the source's properties 
       属性用g_object_get（）读取，用g_object_set（）写入。
       更改了videotestsrc的“pattern”属性，该属性控制元素输出的测试视频的类型。
    */
    g_object_set (data.source, "location", "rtsp://deepcong:666@192.168.100.52:5/0", NULL);
    g_object_set(G_OBJECT(data.sink), "location", "test666.jpg", NULL);


    /* Connect to the pad-added signal */
    g_signal_connect (data.source, "pad-added", G_CALLBACK (pad_added_handler), &data);
 
 
    /* Create the empty pipeline 
       GStreamer中的所有元素通常必须包含在管道中才能使用，负责一些时钟和消息传递功能。
    */
    data.pipeline = gst_pipeline_new ("test-pipeline");


    //&& 如果两个操作数都非零，则条件为真；
    // || 如果两个操作数中有任意一个非零，则条件为真。
    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.depay, data.parse, data.avdec, data.convert, data.encoder,data.sink, NULL);
    if (!gst_element_link_many (data.depay, data.parse, data.avdec, data.convert,data.encoder, data.sink, NULL)) {
        g_printerr ("Elements could not be linked.\n");
        gst_object_unref (data.pipeline);
        return -1;
    }
 
    /* 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->depay, "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_get_current_caps (new_pad);
    new_pad_struct = gst_caps_get_structure (new_pad_caps, 0);
    new_pad_type = gst_structure_get_name (new_pad_struct);
 
    /* 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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编译：

gcc demo.c -o demo `pkg-config --cflags --libs gstreamer-1.0`
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运行：

./demo
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