Python - Gstreamer - appsrc plugin - RTSP stream - NVIDIA Jetson Orin NX - JetPack 5.1.1

Gstreamer - appsrc plugin - RTSP stream

Nvidia Jetson Orin NX,
Python 3.8.10

Below I presented code of simple script, that allow to read frames saved in some directory and stream them out through RTSP, based on Gstreamer and appsrc plugin.


Stream is unavailable. When trying to connect, the logs shown below appear.

0:00:23.079044717 6221 0x1a6d5980 WARN rtspmedia rtsp-media.c:3272:wait_preroll: failed to preroll pipeline
0:00:23.079120655 6221 0x1a6d5980 WARN rtspmedia rtsp-media.c:3652:gst_rtsp_media_prepare: failed to preroll pipeline
0:00:23.082524155 6221 0x1a6d5980 ERROR rtspclient rtsp-client.c:1077:find_media: client 0x1a6ca4c0: can’t prepare media
0:00:23.083076039 6221 0x1a6d5980 ERROR rtspclient rtsp-client.c:2963:handle_describe_request: client 0x1a6ca4c0: no media

Problem could be related to incorrectness pipeline or data delivery to appsrc Gstreamer plugin? Please about any suggestions.

#!/usr/bin/env python3
import cv2
import gi
import signal
from typing import List
import os
import time
import logging

gi.require_version('Gst', '1.0')
gi.require_version('GstRtspServer', '1.0')

from gi.repository import Gst, GLib, GObject, GstRtspServer


# logs
logging.basicConfig(level=logging.DEBUG, filename='app.log', filemode='w')
logger = logging.getLogger(__name__)

class FrameProvider:
    def __init__(self, folder_path: str, img_format: str = 'jpg'):
        self.folder_path = folder_path
        self.img_format = img_format
        self.image_index = 0
        self.files = self.get_files(folder_path)

    # function generate full path to images in folder
    def get_files(self, folder_path) -> List[str]:
        files_path_list = []
        start_time = time.time()
        for i in os.listdir(folder_path):
            if i.endswith(f'.{self.img_format}'):
                full_path = os.path.join(folder_path, i)
        end_time = time.time()
        print(f'Number of loaded paths : {len(files_path_list)}, loading time: {end_time-start_time}')
        return files_path_list
    def get_frame_tobytes(self) -> bytes:
        logger.debug('Wywolanie get_frame_tobytes()')
        if self.image_index < len(self.files):
            frame = cv2.imread(self.files[self.image_index])
            self.image_index += 1
            flag_jpg, encoded_image = cv2.imencode(f'.{self.img_format}', frame)
            if not flag_jpg:
                logger.error('FrameProvider - get_frame_tobytes() : Unable to frame encode.')
                raise ValueError('FrameProvider - get_frame_tobytes() : Unable to frame encode.')
            encoded_image_bytes = encoded_image.tobytes()
            logger.debug(f'FrameProvider - get_frame_tobytes() : Successfully frame encoded, buffer size: {len(encoded_image_bytes)} .')
            return encoded_image_bytes

            logger.debug('FrameProvider - get_frame_tobytes() : All frames have been processed. ')
            return None # return none if all fiels have been processed

class CustomRTSPMediaFactory(GstRtspServer.RTSPMediaFactory):
    def __init__(self, fps, frame_provider, **properties):
        # super(CustomRTSPMediaFactory, self).__init__(**properties)
        self.frame_provider = frame_provider
        self.duration = 1/fps * Gst.SECOND
        self.number_frames = 0
        self.launch_string = f'appsrc name=source is-live=true block=true format=GST_FORMAT_TIME caps=video/x-raw,format=BGR,width=1936,height=1216,framerate={fps}/1 ! videoconvert ! video/x-raw,format=NV12 ! x264enc speed-preset=ultrafast tune=zerolatency ! rtph264pay name=pay0'

    def do_create_element(self, url):
        return Gst.parse_launch(self.launch_string)
    def do_create(self, rtsp_media):
        appsrc = rtsp_media.get_element().get_child_by_name('source')
        appsrc.connect('need-data', self.on_need_data)
    def on_need_data(self, src, length):
        logger.debug('CustomRTSPMediaFactory - on_need_data() : method calling')
            frame = self.frame_provider.get_frame_tobytes()
            if frame:
                buf = Gst.Buffer.new_allocate(None, len(frame), None)
                buf.fill(0, frame)
                buf.duration = self.duration
                timestamp = self.number_frames * self.duration
                buf.pts = buf.dts = int(timestamp)
                buf.offset = timestamp
                self.number_frames += 1
                retval = src.emit('push-buffer', buf)
                if retval != Gst.FlowReturn.OK:
                    logger.error(f'CustomRTSPMediaFactory - on_need_data() : Error pushing buffer {retval}')
                    logger.debug('CustomRTSPMediaFactory - on_need_data() : Buffer pushed successfully')
        except Exception as e:
            logger.error(f'CustomRTSPMediaFactory - on_need_data() : Error : {e}')

def main():
    dir_path = '/home/recomputer/test_images'
    frame_provider = FrameProvider(dir_path, 'jpg')  # Set 10 fps for example frame provider
    server = GstRtspServer.RTSPServer()
    factory = CustomRTSPMediaFactory(10, frame_provider)
    server.get_mount_points().add_factory("/stream", factory)  # Stream available under rtsp://<server_address>:8554/stream
    signal.signal(signal.SIGINT, signal.SIG_DFL)  # Allow to close server with using Ctrl+C


if __name__ == "__main__":

You may try the reference sample test-appsrc:
Using RTSP encode (with H264) and stream images at device memory on Xavier - #6 by Appletree

Please download the sample of v1.162 and give it a try.

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