video delay whith ttyS0 #699

I'm using PICAMERA v1.13 to send an h264 video in the "ttyS0" with a raspberrypi zero, but the video appears with a delay of 1s or more.
Using example 3.13. Recording to a network stream, I don't have this delay in bronser.
Below command used.

import pickup

os.system("sudo chmod o+rw /dev/ttyS0")
os.system("sudo stty -F /dev/ttyS0 2000000")
os.system("sudo stty -F /dev/ttyS0 raw")

camera = picamera.PiCamera()
camera.resolution = (640, 480)
camera.start_recording('/dev/ttyS0', bitrate=500000)
camera.wait_recording(60)
camera.stop_recording()

Using the raspivid terminal command, this delay is less than 100ms.
raspivid -t 0 -n -ih -w 1280 -h 720 -hf -vf -fps 30 -b 500000 -o /dev/ttyS0

I'm trying to have the video on the control of skydroid T10 obtained via camera with raspberry pi zero.