RTMP stream from OpenCV/cv2 to an nginx server, but client get just a green window

Question

I would like to implement a surveillance server to detect objects with openCV.

For this I setup an Ubuntu server for this workflow:

Mobile CAM (from an Android) stream
|
| put the stream with RTMP to server rtmp://nginx/live/in [1]
|
v
nginx with the rtmp plugin
^
|
| the python script gets the mobile CAM stream from nginx rtmp://nginx/live/in [2]
|
v
surveillance script
|
| Stream to output back to rtmp://nginx/live/out with the results [3]
|
v
nginx with the rtmp plugin
^
|
| get the output stream from nginx rtmp://nginx/live/in [4]
|
RTMP stream client

I'm really not in the deep with stream and RTMP paramters. Up to now, I got [1] and [2] working, so I have the video from the mobile CAM in the frame from the phython OpenCV script.

On the destination client [4] (I use ffplay rtmp://nginx/live/out), I just have a green window, nothing else in it.

I use this for the streaming part:

...
                send_gst = "appsrc ! videoconvert ! video/x-raw,format=I420,clock-rate=90000 ! x264enc ! video/x-h264,stream-format=(string)byte-stream,alignment=(string)au ! h264parse ! queue ! flvmux ! rtmpsink location=rtmp://nginx/live/out"
                writer = cv2.VideoWriter(send_gst, 0, 20, (520, 380), True)
...
        if writer is not None:
                writer.write(frame)
...

Maybe there is someone who can give me some hints or which part of code is needet to help me.

Answer 1

Solved, the source and destination resolution should be the same