Streaming android screen using Webrtc + python

Question

I'm trying to stream android screen using python + aiortc. I have a POC to obtain the device screen using adb + screenrecord. The provided code reads the raw output (h264) from the execution of screenrecord and shows it using ffmpeg and opencv.

import subprocess as sp
import cv2
import array
import numpy as np

adbCmd = ['adb', 'exec-out', 'screenrecord', '--output-format=h264', '-']
stream = sp.Popen(adbCmd, stdout= sp.PIPE, universal_newlines = True)

ffmpegCmd = ['ffmpeg', '-i', '-', '-f', 'rawvideo', '-vcodec', 'bmp', '-vf', 'fps=5', '-']
ffmpeg = sp.Popen(ffmpegCmd, stdin=stream.stdout, stdout=sp.PIPE)

while True:
    fileSizeBytes = ffmpeg.stdout.read(6)
    fileSize = 0
    for i in range(4):
        fileSize += fileSizeBytes[i + 2] * 256 ** i
    bmpData = fileSizeBytes + ffmpeg.stdout.read(fileSize - 6)
    image = cv2.imdecode(np.fromstring(bmpData, dtype=np.uint8), 1)
    cv2.imshow("im", image)
    cv2.waitKey(25)

Currently, I'm trying to plug the output from ffmpeg or adb exec-out to an aiortc media streamer. Based on this example I replaced the recv method with the fallowing code

async def recv(self):
    fileSizeBytes = ffmpeg.stdout.read(6)
    fileSize = 0
    for i in range(4):
        fileSize += fileSizeBytes[i + 2] * 256 ** i
    bmpData = fileSizeBytes + ffmpeg.stdout.read(fileSize - 6)
    image = cv2.imdecode(numpy.fromstring(bmpData, dtype=numpy.uint8), 1)

    frame = VideoFrame.from_ndarray(
        image, format="bgr24"
    )

    pts, time_base = await self.next_timestamp()
    frame.pts = pts
    frame.time_base = time_base
    self.counter += 1
    return frame

But this code is not able to stream the correct video from device screen and no error happen. I'm looking for solutions for this problem. I was thinking to use the direct output from adbCmd but it also didn't worked.