写一个deepstream c++版本推流代码

以下是一个基本的 DeepStream C 版本推流代码，使用 NVIDIA NVENC 编码器和 RTSP 协议。

#include <gst/gst.h>
#include <gst/rtsp-server/rtsp-server.h>
#include <cuda_runtime_api.h>
#include <nvdsgstutils.h>
#include <nvcuviddec.h>
#include <nvbufsurface.h>
#include <nvbufsurftransform.h>
#include <nvdsinfer.h>
#include <nvdsinfer_context.h>
#include <nvdsinfer_custom_impl.h>
#include <nvdsinfer_tensorrt.h>

#define DEFAULT_BITRATE 4000000
#define DEFAULT_FRAMERATE 30
#define DEFAULT_WIDTH 1920
#define DEFAULT_HEIGHT 1080
#define DEFAULT_FORMAT "I420"
#define DEFAULT_CODEC "h264"
#define DEFAULT_PORT "8554"

typedef struct {
    GstElement *pipeline;
    GstElement *source;
    GstElement *streammux;
    GstElement *nvinfer;
    GstElement *nvvidconv;
    GstElement *nvenc;
    GstElement *rtppay;
    GstElement *sink;
} AppCtx;

static gboolean bus_call(GstBus *bus, GstMessage *msg, gpointer data)
{
    switch (GST_MESSAGE_TYPE(msg)) {
        case GST_MESSAGE_EOS:
            g_print("End of stream\n");
            g_main_loop_quit((GMainLoop *)data);
            break;
        case GST_MESSAGE_ERROR: {
            gchar *debug;
            GError *error;

            gst_message_parse_error(msg, &error, &debug);
            g_printerr("Error: %s\n", error->message);
            g_error_free(error);
            g_free(debug);
            g_main_loop_quit((GMainLoop *)data);
            break;
        }
        default:
            break;
    }

    return TRUE;
}

static GstPadProbeReturn cb_have_data(GstPad *pad, GstPadProbeInfo *info, gpointer user_data)
{
    GstBuffer *buf = GST_PAD_PROBE_INFO_BUFFER(info);
    AppCtx *appctx = (AppCtx *)user_data;

    GstMapInfo map;
    gst_buffer_map(buf, &map, GST_MAP_READ);

    CUdeviceptr in_device_ptr = 0;
    CUdeviceptr out_device_ptr = 0;
    NvBufSurface *surface = NULL;
    NvBufSurfaceCreateParams create_params = {0};
    NvBufSurfaceTransformParams transform_params = {0};
    NvBufSurfaceParams surface_params = {0};
    NvBufSurfaceMapParams map_params = {0};
    NvDsBatchMeta *batch_meta = NULL;

    create_params.gpuId = 0;
    create_params.width = appctx->source_width;
    create_params.height = appctx->source_height;
    create_params.size = appctx->source_width * appctx->source_height * 3 / 2;
    create_params.colorFormat = appctx->source_format == NvBufSurfaceColorFormat_I420 ? NvBufSurfaceColorFormat_I420 : NvBufSurfaceColorFormat_RGBA;
    create_params.layout = NvBufSurfaceLayout_Pitch;

    if (NvBufSurfaceCreate(&surface, 1, &create_params) != 0) {
        g_print("Error: failed to create surface\n");
        goto done;
    }

    surface_params.src_rect.width = appctx->source_width;
    surface_params.src_rect.height = appctx->source_height;
    surface_params.src_rect.top = 0;
    surface_params.src_rect.left = 0;
    surface_params.dst_rect.width = appctx->stream_width;
    surface_params.dst_rect.height