Realize low-latency transmission of rtsp video stream, and ' Application provided invalid, non monotonically increasing dts to muxer in stream 0' problem

[Baby-Feng]

Hello, I want to achieve low-latency transmission of rtsp video streams through ffmpeg-python, here is my code:
`
process1 = (
ffmpeg
.input('rtsp://localhost/test',format='rtsp')
.output('pipe:', vcodec='copy')
.run_async(pipe_stdout=True)
)

process2 = (
ffmpeg
.input('pipe:', format='rawvideo', s='{}x{}'.format(width, height))
.output('rtsp://localhost/test', format='rtsp', vcodec='copy')
.overwrite_output()
.run_async(pipe_stdin=True)
)

while True:
in_bytes = process1.stdout.read(width * height * 3)
if not in_bytes:
break
in_frame = (
np.frombuffer(in_bytes, np.uint8) # numpy.ndarry
.reshape([height, width, 3])
)
out_frame = in_frame * 0.3
process2.stdin.write(out_frame.astype(np.uint8).tobytes())

process2.stdin.close()
process1.wait()
process2.wait(）
`
One problem is that I set vcodec='copy' in process1 at the receiving end (local rtsp server) of the video stream, and the streaming delay drops significantly (<0.5s), but there will be
'Application provided invalid, non monotonically increasing dts to muxer in stream 0' (error or warning?),
But the program can still continue to execute. How should I modify the code and parameters, or is there a better solution?
Thanks!