python-thingserver/example/mjpeg-stream.py at master · labthings/python-thingserver · GitHub

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from __future__ import division

import asyncio

import io

import logging

import sys

import time

from datetime import datetime

from PIL import Image, ImageDraw

from thingserver import Property, Thing, Value, WebThingServer

if (

sys.version_info[0] == 3

and sys.version_info[1] >= 8

and sys.platform.startswith("win")

asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

"""

PIL spams the logger with debug-level information. This is a pain when debugging api.app.

We override the logging settings in api.app by setting a level for PIL here.

"""

pil_logger = logging.getLogger("PIL")

pil_logger.setLevel(logging.INFO)

class StreamGenerator:

"""An example image streamer class"""

def __init__(self):

self.stream = io.BytesIO() # Byte stream to hold the latest JPEG frame

self.running = False # Is the stream frame generator running

self.event = asyncio.Event() # Event to signal a new frame is ready

def _start_runner(self):

print("Starting frame runner")

# Run frame generator loop in a coroutine task

task = asyncio.create_task(self.frame_loop())

self.running = True

return task

def generate_new_dummy_image(self):

# Create a dummy image to serve in the stream

image = Image.new("RGB", (640, 480), color=(0, 0, 0),)

draw = ImageDraw.Draw(image)

draw.text(

(20, 70),

"Current time: {}".format(datetime.now().strftime("%d/%m/%Y, %H:%M:%S")),

)

# Save new image to the stream

image.save(self.stream, format="JPEG")

async def frame_loop(self):

while True:

# Only serve frames at 1fps

await asyncio.sleep(1)

# Signal we're in the middle of writing a new frame

self.event.clear()

# Reset stream

self.stream.seek(0)

self.stream.truncate()

# Generate new dumm image

self.generate_new_dummy_image()

# Signal a new frame is ready

self.event.set()

async def stream_generator(self):

if not self.running:

self._start_runner()

served_image_timestamp = time.time()

my_boundary = "--boundarydonotcross\n"

while True:

interval = 1.0

if served_image_timestamp + interval < time.time():

# Wait for current frame to finish being generated

await self.event.wait()

# Get the current frame

img = self.stream.getvalue()

# Add frame header data

served_image_timestamp = time.time()

prefix = (

my_boundary

+ "Content-type: image/jpeg\r\n"

+ "Content-length: %s\r\n\r\n" % len(img)

)

yield prefix.encode() + img

else:

# Delay by interval before checking for next frame

await asyncio.sleep(interval)

async def snapshot(self):

if not self.running:

self._start_runner()

await self.event.wait()

return self.stream.getvalue()

def make_thing():

stream_generator = StreamGenerator()

thing = Thing(

"urn:dev:ops:my-lamp-1234",

"My Lamp",

["OnOffSwitch", "Light"],

"A web connected lamp",

)

thing.add_property(

Property(

thing,

"snapshot",

Value(None, stream_generator.snapshot, None),

metadata={"title": "Snapshot", "readOnly": True},

content_type="image/jpeg",

)

thing.add_property(

Property(

thing,

"stream",

Value(None, stream_generator.stream_generator, None),

metadata={"title": "Stream", "readOnly": True},

content_type="multipart/x-mixed-replace;boundary=--boundarydonotcross",

)

return thing

def run_server():

thing = make_thing()

server = WebThingServer(thing, port=8888, debug=True)

try:

logging.info("starting the server")

server.start()

except KeyboardInterrupt:

logging.info("stopping the server")

server.stop()

logging.info("done")

if __name__ == "__main__":

logging.basicConfig(

level=10, format="%(asctime)s %(filename)s:%(lineno)s %(levelname)s %(message)s"

)

run_server()

python-thingserver/example/mjpeg-stream.py at master · labthings/python-thingserver · GitHub

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