How to avoid a delay in RTP streaming

Please provide complete information as applicable to your setup.

• Hardware Platform Jetson
• DeepStream Version 5.0 DP
• JetPack Version 32
• TensorRT Version 7.1.0-1+cuda10.2

Hey. I am using Jetson Xavier NX. I am trying to combine and in order to capture RTSP streams, apply object detection to them and send them via RTP to Janus. The problem is that during the execution of the script there is a delay, which accumulates over time. Please tell me which flags to use in order to avoid this, that is, to drop frames or make the stream go right through from input to output, and the graphics from the frame that was captured once were superimposed on the current frame. Thank. Good luck.

My code
#!/usr/bin/env python3
import sys

import gi
import configparser

gi.require_version('Gst', '1.0')
from gi.repository import GObject, Gst, GstRtspServer
from gi.repository import GLib
from ctypes import *
import time
import sys
import math
import platform
from common.is_aarch_64 import is_aarch64
from common.bus_call import bus_call
from common.FPS import GETFPS
import numpy as np
import pyds
import cv2
import os
import os.path
from os import path

fps_streams = {}
frame_count = {}
saved_count = {}

global codec
codec = "H264"
global bitrate
bitrate = 4096000
# global stream_path

pgie_classes_str = ["Vehicle", "TwoWheeler", "Person", "RoadSign"]

# tiler_sink_pad_buffer_probe  will extract metadata received on tiler src pad
# and update params for drawing rectangle, object information etc.
def tiler_sink_pad_buffer_probe(pad, info, u_data):
    frame_number = 0
    num_rects = 0
    gst_buffer = info.get_buffer()
    if not gst_buffer:
        print("Unable to get GstBuffer ")

    # Retrieve batch metadata from the gst_buffer
    # Note that pyds.gst_buffer_get_nvds_batch_meta() expects the
    # C address of gst_buffer as input, which is obtained with hash(gst_buffer)
    batch_meta = pyds.gst_buffer_get_nvds_batch_meta(hash(gst_buffer))

    l_frame = batch_meta.frame_meta_list
    while l_frame is not None:
            # Note that needs a cast to pyds.NvDsFrameMeta
            # The casting is done by pyds.NvDsFrameMeta.cast()
            # The casting also keeps ownership of the underlying memory
            # in the C code, so the Python garbage collector will leave
            # it alone.
            frame_meta = pyds.NvDsFrameMeta.cast(
        except StopIteration:

        frame_number = frame_meta.frame_num
        l_obj = frame_meta.obj_meta_list
        num_rects = frame_meta.num_obj_meta
        is_first_obj = True
        save_image = False
        obj_counter = {
            PGIE_CLASS_ID_VEHICLE: 0,
            PGIE_CLASS_ID_PERSON: 0,
            PGIE_CLASS_ID_BICYCLE: 0,
        while l_obj is not None:
                # Casting to pyds.NvDsObjectMeta
                obj_meta = pyds.NvDsObjectMeta.cast(
            except StopIteration:
            obj_counter[obj_meta.class_id] += 1
            # Periodically check for objects with borderline confidence value that may be false positive detections.
            # If such detections are found, annoate the frame with bboxes and confidence value.
            # Save the annotated frame to file.
            if ((saved_count["stream_" + str(frame_meta.pad_index)] % 30 == 0) and (
                    obj_meta.confidence > 0.3 and obj_meta.confidence < 0.31)):
                if is_first_obj:
                    is_first_obj = False
                    # Getting Image data using nvbufsurface
                    # the input should be address of buffer and batch_id
                    n_frame = pyds.get_nvds_buf_surface(hash(gst_buffer), frame_meta.batch_id)
                    # convert python array into numy array format.
                    frame_image = np.array(n_frame, copy=True, order='C')
                    # covert the array into cv2 default color format
                    frame_image = cv2.cvtColor(frame_image, cv2.COLOR_RGBA2BGRA)

                save_image = True
                frame_image = draw_bounding_boxes(frame_image, obj_meta, obj_meta.confidence)
                l_obj =
            except StopIteration:

        # print("Frame Number=", frame_number, "Number of Objects=", num_rects, "Vehicle_count=",
        #       obj_counter[PGIE_CLASS_ID_VEHICLE], "Person_count=", obj_counter[PGIE_CLASS_ID_PERSON])
        # Get frame rate through this probe

        saved_count["stream_" + str(frame_meta.pad_index)] += 1
            l_frame =
        except StopIteration:

    return Gst.PadProbeReturn.OK

def draw_bounding_boxes(image, obj_meta, confidence):
    confidence = '{0:.2f}'.format(confidence)
    rect_params = obj_meta.rect_params
    top = int(
    left = int(rect_params.left)
    width = int(rect_params.width)
    height = int(rect_params.height)
    obj_name = pgie_classes_str[obj_meta.class_id]
    image = cv2.rectangle(image, (left, top), (left + width, top + height), (0, 0, 255, 0), 2)
    # Note that on some systems cv2.putText erroneously draws horizontal lines across the image
    image = cv2.putText(image, obj_name + ',C=' + str(confidence), (left - 10, top - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.5,
                        (0, 0, 255, 0), 2)
    return image

def cb_newpad(decodebin, decoder_src_pad, data):
    print("In cb_newpad\n")
    caps = decoder_src_pad.get_current_caps()
    gststruct = caps.get_structure(0)
    gstname = gststruct.get_name()
    source_bin = data
    features = caps.get_features(0)

    # Need to check if the pad created by the decodebin is for video and not
    # audio.
    if (gstname.find("video") != -1):
        # Link the decodebin pad only if decodebin has picked nvidia
        # decoder plugin nvdec_*. We do this by checking if the pad caps contain
        # NVMM memory features.
        if features.contains("memory:NVMM"):
            # Get the source bin ghost pad
            bin_ghost_pad = source_bin.get_static_pad("src")
            if not bin_ghost_pad.set_target(decoder_src_pad):
                sys.stderr.write("Failed to link decoder src pad to source bin ghost pad\n")
            sys.stderr.write(" Error: Decodebin did not pick nvidia decoder plugin.\n")

def decodebin_child_added(child_proxy, Object, name, user_data):
    print("Decodebin child added:", name, "\n")
    if (name.find("decodebin") != -1):
        Object.connect("child-added", decodebin_child_added, user_data)
    if (is_aarch64() and name.find("nvv4l2decoder") != -1):
        print("Seting bufapi_version\n")
        Object.set_property("bufapi-version", True)

def create_source_bin(index, uri):
    print("Creating source bin")

    # Create a source GstBin to abstract this bin's content from the rest of the
    # pipeline
    bin_name = "source-bin-%02d" % index
    nbin =
    if not nbin:
        sys.stderr.write(" Unable to create source bin \n")

    # Source element for reading from the uri.
    # We will use decodebin and let it figure out the container format of the
    # stream and the codec and plug the appropriate demux and decode plugins.
    uri_decode_bin = Gst.ElementFactory.make("uridecodebin", "uri-decode-bin")
    if not uri_decode_bin:
        sys.stderr.write(" Unable to create uri decode bin \n")
    # We set the input uri to the source element
    uri_decode_bin.set_property("uri", uri)
    # Connect to the "pad-added" signal of the decodebin which generates a
    # callback once a new pad for raw data has beed created by the decodebin
    uri_decode_bin.connect("pad-added", cb_newpad, nbin)
    uri_decode_bin.connect("child-added", decodebin_child_added, nbin)

    # We need to create a ghost pad for the source bin which will act as a proxy
    # for the video decoder src pad. The ghost pad will not have a target right
    # now. Once the decode bin creates the video decoder and generates the
    # cb_newpad callback, we will set the ghost pad target to the video decoder
    # src pad.
    Gst.Bin.add(nbin, uri_decode_bin)
    bin_pad = nbin.add_pad(Gst.GhostPad.new_no_target("src", Gst.PadDirection.SRC))
    if not bin_pad:
        sys.stderr.write(" Failed to add ghost pad in source bin \n")
        return None
    return nbin

def main(args):
    # Check input arguments
    if len(args) < 1:
        sys.stderr.write("usage: %s <uri1> [uri2] ... [uriN] \n" % args[0])

    # for i in range(0, len(args) - 1):
    #     fps_streams["stream{0}".format(i)] = GETFPS(i)
    number_sources = len(args) - 1

    # Standard GStreamer initialization

    # Create gstreamer elements */
    # Create Pipeline element that will form a connection of other elements
    print("Creating Pipeline \n ")
    pipeline = Gst.Pipeline()
    is_live = False

    if not pipeline:
        sys.stderr.write(" Unable to create Pipeline \n")
    print("Creating streamux \n ")

    # Create nvstreammux instance to form batches from one or more sources.
    streammux = Gst.ElementFactory.make("nvstreammux", "Stream-muxer")
    if not streammux:
        sys.stderr.write(" Unable to create NvStreamMux \n")

    for i in range(number_sources):

        frame_count["stream_" + str(i)] = 0
        saved_count["stream_" + str(i)] = 0
        print("Creating source_bin ", i, " \n ")
        uri_name = args[i + 1]
        if uri_name.find("rtsp://") == 0:
            is_live = True
        source_bin = create_source_bin(i, uri_name)
        if not source_bin:
            sys.stderr.write("Unable to create source bin \n")
        padname = "sink_%u" % i
        sinkpad = streammux.get_request_pad(padname)
        if not sinkpad:
            sys.stderr.write("Unable to create sink pad bin \n")
        srcpad = source_bin.get_static_pad("src")
        if not srcpad:
            sys.stderr.write("Unable to create src pad bin \n")

    print("Creating Pgie \n ")

    pgie = Gst.ElementFactory.make("nvinfer", "primary-inference")
    if not pgie:
        sys.stderr.write("Unable to create pgie \n")
    # Add nvvidconv1 and filter1 to convert the frames to RGBA
    # which is easier to work with in Python.
    print("Creating nvvidconv1 \n ")
    nvvidconv1 = Gst.ElementFactory.make("nvvideoconvert", "convertor1")
    if not nvvidconv1:
        sys.stderr.write(" Unable to create nvvidconv1 \n")
    print("Creating filter1 \n ")
    caps1 = Gst.Caps.from_string("video/x-raw(memory:NVMM), format=RGBA")
    filter1 = Gst.ElementFactory.make("capsfilter", "filter1")
    if not filter1:
        sys.stderr.write(" Unable to get the caps filter1 \n")
    filter1.set_property("caps", caps1)
    print("Creating tiler \n ")
    tiler = Gst.ElementFactory.make("nvmultistreamtiler", "nvtiler")
    if not tiler:
        sys.stderr.write(" Unable to create tiler \n")
    print("Creating nvvidconv \n ")
    nvvidconv = Gst.ElementFactory.make("nvvideoconvert", "convertor")
    if not nvvidconv:
        sys.stderr.write(" Unable to create nvvidconv \n")
    print("Creating nvosd \n ")
    nvosd = Gst.ElementFactory.make("nvdsosd", "onscreendisplay")
    if not nvosd:
        sys.stderr.write(" Unable to create nvosd \n")

    nvvidconv_postosd = Gst.ElementFactory.make("nvvideoconvert", "convertor_postosd")
    if not nvvidconv_postosd:
        sys.stderr.write(" Unable to create nvvidconv_postosd \n")

    # Create a caps filter
    caps = Gst.ElementFactory.make("capsfilter", "filter")
    caps.set_property("caps", Gst.Caps.from_string("video/x-raw(memory:NVMM), format=NV12, payload=(int)96"))

    # Make the encoder
    if codec == "H264":
        encoder = Gst.ElementFactory.make("nvv4l2h264enc", "encoder")
        print("Creating H264 Encoder")
    elif codec == "H265":
        encoder = Gst.ElementFactory.make("nvv4l2h265enc", "encoder")
        print("Creating H265 Encoder")
    if not encoder:
        sys.stderr.write(" Unable to create encoder")
    encoder.set_property('bitrate', bitrate)
    if is_aarch64():
        encoder.set_property('preset-level', 1)
        encoder.set_property('insert-sps-pps', 1)
        encoder.set_property('bufapi-version', 1)

    encoder.set_property("maxperf-enable", 1)
    encoder.set_property("preset-level", 1)
    encoder.set_property("control-rate", 1)
    encoder.set_property('insert-sps-pps', 1)
    encoder.set_property('bufapi-version', 1)

    # Make the payload-encode video into RTP packets
    if codec == "H264":
        rtppay = Gst.ElementFactory.make("rtph264pay", "rtppay")
        print("Creating H264 rtppay")
        rtppay.set_property("config-interval", -1)
        rtppay.set_property("pt", 96)
        rtppay.set_property("mtu", 640)
    elif codec == "H265":
        rtppay = Gst.ElementFactory.make("rtph265pay", "rtppay")
        print("Creating H265 rtppay")
    if not rtppay:
        sys.stderr.write("Unable to create rtppay")

    queue = Gst.ElementFactory.make("queue", None)
    queue.set_property("leaky", 2)
    queue.set_property("max-size-time", 0)
    # Make the UDP sink
    updsink_port_num = 8200
    sink = Gst.ElementFactory.make("udpsink", "udpsink")
    if not sink:
        sys.stderr.write(" Unable to create udpsink")

    sink.set_property('host', '')
    sink.set_property('port', updsink_port_num)
    sink.set_property('async', False)
    sink.set_property('sync', 0)

    if (is_aarch64()):
        print("Creating transform \n ")
        transform = Gst.ElementFactory.make("nvegltransform", "nvegl-transform")
        if not transform:
            sys.stderr.write(" Unable to create transform \n")

    # print("Creating EGLSink \n")
    # sink = Gst.ElementFactory.make("nveglglessink", "nvvideo-renderer")
    # if not sink:
    #     sys.stderr.write(" Unable to create egl sink \n")

    if is_live:
        print("Atleast one of the sources is live")
        streammux.set_property('live-source', 1)

    streammux.set_property('width', 1920)
    streammux.set_property('height', 1080)
    streammux.set_property('batch-size', number_sources)
    streammux.set_property('batched-push-timeout', 4000000)
    pgie.set_property('config-file-path', "dstest_imagedata_config.txt")
    pgie_batch_size = pgie.get_property("batch-size")
    if (pgie_batch_size != number_sources):
        print("WARNING: Overriding infer-config batch-size", pgie_batch_size, " with number of sources ",
              number_sources, " \n")
        pgie.set_property("batch-size", number_sources)
    tiler_rows = int(math.sqrt(number_sources))
    tiler_columns = int(math.ceil((1.0 * number_sources) / tiler_rows))
    tiler.set_property("rows", tiler_rows)
    tiler.set_property("columns", tiler_columns)
    tiler.set_property("width", TILED_OUTPUT_WIDTH)
    tiler.set_property("height", TILED_OUTPUT_HEIGHT)

    sink.set_property("sync", 0)

    if not is_aarch64():
        # Use CUDA unified memory in the pipeline so frames
        # can be easily accessed on CPU in Python.
        mem_type = int(pyds.NVBUF_MEM_CUDA_UNIFIED)
        streammux.set_property("nvbuf-memory-type", mem_type)
        nvvidconv.set_property("nvbuf-memory-type", mem_type)
        nvvidconv1.set_property("nvbuf-memory-type", mem_type)
        tiler.set_property("nvbuf-memory-type", mem_type)

    print("Adding elements to Pipeline \n")



    print("Linking elements in the Pipeline \n")


    # create an event loop and feed gstreamer bus mesages to it
    loop = GObject.MainLoop()
    bus = pipeline.get_bus()
    bus.connect("message", bus_call, loop)

    tiler_sink_pad = tiler.get_static_pad("sink")
    if not tiler_sink_pad:
        sys.stderr.write(" Unable to get src pad \n")
        tiler_sink_pad.add_probe(Gst.PadProbeType.BUFFER, tiler_sink_pad_buffer_probe, 0)

    # List the sources
    print("Now playing...")
    for i, source in enumerate(args):
        if (i != 0):
            print(i, ": ", source)

    print("Starting pipeline \n")
    # start play back and listed to events
    # cleanup
    print("Exiting app\n")

if __name__ == '__main__':

Can you clarify what kind of delay and how did you measure it?

I think, generally, i’m talking about this problem:

@t333ga The link is a good instruction for checking the buffer dropping problem.