Custom output for writing individual JPEGs from an MJPEG

lots_of_jpegs.py

import io
import picamera

class MyOutput(object):
    def __init__(self):
        self.file_num = 0
        self.output = None

    def write(self, buf):
        if buf.startswith(b'\xff\xd8'):
            if self.output:
                self.output.close()
            self.file_num += 1
            self.output = io.open('%d.jpg' % self.file_num, 'wb')
        self.output.write(buf)


with picamera.PiCamera() as camera:
    camera.resolution = (1280, 720)
    camera.start_recording(MyOutput(), format='mjpeg')
    camera.wait_recording(10)
    camera.stop_recording()

lots_of_jpegs_when_u_want.py

import io
import picamera
import curses

class MyOutput(object):
    def __init__(self):
        self.file_num = 0
        self.write_frame = False
        self.output = None

    def write(self, buf):
        if buf.startswith(b'\xff\xd8'):
            if self.output:
                self.output.close()
            self.output = None
            if self.write_frame:
                self.file_num += 1
                self.output = io.open('%d.jpg' % self.file_num, 'wb')
                self.write_frame = False
        if self.output:
            self.output.write(buf)


def main(window):
    window.nodelay(True)
    with picamera.PiCamera(resolution=(1280, 720), framerate=15) as camera:
        output = MyOutput()
        camera.start_recording(output, format='mjpeg')
        try:
            while True:
                window.addstr(0, 0, 'Press Q to quit')
                window.addstr(2, 0, 'Press F to capture a frame')
                window.addstr(3, 0, 'Filename: %d.jpg' % output.file_num)
                window.refresh()
                c = window.getch()
                if c == ord('q'):
                    break
                elif c == ord('f'):
                    output.write_frame = True
                camera.wait_recording(0.1)
        finally:
            camera.stop_recording()

curses.initscr()
curses.wrapper(main)