Make jetson_utils work with gstreamer and yolov8 api

[samthephantom]

Hi dusty. I used to decode h.264-codec rtsp camera stream with gstreamer python api ( I built the pipeline with nvv4l2decoder and nvvidconv). Here is the detail:

1. The pipeline convert image from NVMM to CPU RAM with nvvidconv
2. I get the decoded image data from appsink by sink.emit("pull-sample").
3. The image data is read and transferred to numpy like this:

def new_buffer(sink, data):
    # pull sample
    sample = sink.emit("pull-sample")
    buf = sample.get_buffer()
    caps = sample.get_caps()

    # create buffer
    arr = np.ndarray(
        (caps.get_structure(0).get_value('height'),
         caps.get_structure(0).get_value('width'),
         4),
        buffer=buf.extract_dup(0, buf.get_size()),
        dtype=np.uint8)
    
    # convert BGRx to RGB for yolov8 inference
    data.img = cv2.cvtColor(arr, cv2.COLOR_BGRA2BGR)
   
   
    data.data_valid()
    data.frame_shape = data.img.shape
    data.frame_timestamp = time.time()

    if data.frame < 10000:
        data.frame = data.frame+1
    else:
        data.frame = 0
    return Gst.FlowReturn.OK

Please share your experience on how to make cudaImage work with gstreamer, thanks. And I couldn't find out if the yolov8 python api accept the cudaImage as input.