How to get image data from memory:NVMM with TX1 R28.1

I have some old remote TX1 which are L4T R28.1.
I want to get image data from nv gstreamer plugin,hower the function “ExtractFdFromNvBuffer” can not find on TX1 with R28.1
Wchic function can work instead of ExtractFdFromNvBuffer on R28.1
Thanks!
my code

gst_parse_launch("filesrc location=1.h264 ! h264parse ! omxh264dec  ! nvvidconv !  video/x-raw(memory:NVMM), format=(string)RGBA ! appsink name=mysink sync=false", NULLr)
...
        GstSample *sample = gst_app_sink_pull_sample(GST_APP_SINK(appsink_));

        if (sample)
        {
            GstBuffer *buffer = gst_sample_get_buffer (sample);
            GstMemory *memory = gst_buffer_get_memory(buffer, 0);
            GstMapInfo info;
            gst_memory_map(memory, &info, GST_MAP_READ);

            if (info.data)
            {

                    //printf("%d\n", idx);
                    int in_dmabuf_fd;
                    gpointer mapped_ptr = NULL;
#ifndef L4TR28
                    ExtractFdFromNvBuffer (info.data, &in_dmabuf_fd);
                    NvBufferMemMap (in_dmabuf_fd, 0, NvBufferMem_Read,&mapped_ptr);
#else
		    //how to get image data 
#endif
                   ....
#ifndef L4TR28
                    if(mapped_ptr)
                        NvBufferMemUnMap (in_dmabuf_fd, 0, &mapped_ptr);
                    else
                        printf("mapped_ptr invilid\n");

                    NvReleaseFd(in_dmabuf_fd);
#else
					//
#endif
            }
            gst_memory_unmap(memory, &info);
            gst_memory_unref(memory);
            gst_sample_unref(sample);
        }
    }

Hi,
On r28.1, you can only get CPU[video/x-raw] buffer. The pipeline looks like:

gst_parse_launch("filesrc location=1.h264 ! h264parse ! omxh264dec  ! nvvidconv !  video/x-raw, format=(string)RGBA ! appsink name=mysink sync=false", NULLr)

You may consider to upgrade and have new NvBuffer APIs.

Thanks.