How to broadcast camera video as RTSP?

1

How to convert each frame obtained by cap.VideoCapture(0) to RTSP output?

2

Hi @frost,

Hmm, maybe you can try using gstreamer appsrc for that?

You can define a gst pipeline that receives your buffers and push them out, something like this (FYI I didn’t test it out is just pseudocode)

pipeline_str = "appsrc ! videoconvert ! x264enc tune=zerolatency bitrate=500 speed-preset=ultrafast ! rtph264pay config-interval=1 pt=96 ! rtspclientsink location=rtsp://127.0.0.1:8554/test"

# Create the GStreamer pipeline
pipeline = Gst.parse_launch(pipeline_str)
appsrc = pipeline.get_by_name("appsrc")

pipeline.set_state(Gst.State.PLAYING)

Then when you have a frame:

# Convert frame for gst
frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
data = frame_rgb.tobytes()
buf = Gst.Buffer.new_allocate(None, len(data), None)
buf.fill(0, data)

# Push the buffer to the appsrc element
appsrc.emit("push-buffer", buf)

Regards,
Bob,
support@proventusnova.com

3

感谢您的回复。我尝试使用以上思想构建了如下代码：

cam_rtsp = 'rtsp://admin:admin123@192.168.1.108:554/cam/realmonitor?channel=1&subtype=0'

import cv2
import gi

gi.require_version('Gst', '1.0')
gi.require_version('GstRtspServer', '1.0')
from gi.repository import Gst, GstRtspServer, GObject, GLib


class SensorFactory(GstRtspServer.RTSPMediaFactory):
    def __init__(self, **properties):
        super(SensorFactory, self).__init__(**properties)
        self.cap = cv2.VideoCapture(cam_rtsp)
        self.number_frames = 0
        self.fps = 25
        self.duration = 1 / self.fps * Gst.SECOND  # duration of a frame in nanoseconds

        self.width = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        self.height = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

        self.launch_string = 'appsrc name=source is-live=true block=true format=GST_FORMAT_TIME ' \
                             f'caps=video/x-raw,format=BGR,width={self.width},height={self.height},framerate={self.fps}/1 ' \
                             f'! autovideoconvert ! video/x-raw,format=I420,width={self.width},height={self.height},framerate={self.fps}/1 ' \
                             '! x264enc speed-preset=ultrafast tune=zerolatency bitrate=500 ' \
                             '! rtph264pay config-interval=1 name=pay0 pt=96'

    def on_need_data(self, src, lenght):
        try:
            if self.cap.isOpened():
                ret, frame = self.cap.read(self.cap.get(cv2.CAP_PROP_FRAME_COUNT) - 1)
                if ret:
                    # 调整图像大小
                    frame = cv2.resize(frame, (self.width, self.height))

                    data = frame.tobytes()
                    buf = Gst.Buffer.new_allocate(None, len(data), None)
                    buf.fill(0, data)
                    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)
                    print('pushed buffer, frame {}, timestamp {}, durations {} s'.format(self.number_frames,
                                                                                         timestamp,
                                                                                         self.duration / Gst.SECOND))
                    if retval != Gst.FlowReturn.OK:
                        print(retval)
        except StopIteration:
            # self.cap.set(cv2.CAP_PROP_POS_FRAMES, 0)
            pass

    def do_create_element(self, url):
        return Gst.parse_launch(self.launch_string)

    def do_configure(self, rtsp_media):
        self.number_frames = 0
        appsrc = rtsp_media.get_element().get_child_by_name('source')
        appsrc.connect('need-data', self.on_need_data)


class GstServer(GstRtspServer.RTSPServer):
    def __init__(self, **properties):
        super(GstServer, self).__init__(**properties)
        self.factory = SensorFactory()
        self.factory.set_shared(True)
        self.get_mount_points().add_factory("/test", self.factory)
        self.attach(None)


if __name__ == "__main__":
    Gst.init(None)

    server = GstServer()

    loop = GLib.MainLoop()
    loop.run()

此时，运行变得非常卡顿。当加载 1080p 清晰度的视频时，延迟高达 30 秒。如何降低延迟？

4

all of that DOES NOT NEED OpenCV at all.

you can do all of that with nothing but gstreamer.

also please write in English. this is an English-speaking forum.