Opencv save frames much more quickly then 25 fps on video file

Question

I'm trying to make a video based on an RTSP stream, opencv creates the file correctly, but when opencv saves frames in this file, the video file quickly shows frames in a short time. In my test, I record frames for 10 seconds, after that I stop recording, when I go to check the video file, what is displayed is a video with duration of 2 seconds, but all recorded frames are present in the file.

My thread to save frames

self.rec = False
self.thread = Thread(target=self.grava_frame, args=())
self.thread.daemon = True
self.thread.start()

def grava_frame(self):
        while True:
            if self.rec:
                #self.rec = False
                while not self.thread_end:
                    frame = cv2.cvtColor(self.resized_cropped, cv2.COLOR_RGB2BGR)
                    self.video_writer.write(frame)
                    cv2.waitKey(1)
                self.video_writer.release()

My thread to capture frames:

self.at_frame = Thread(target=self.atualiza_frame, args=())
        self.at_frame.daemon = True
        self.at_frame.start()
def atualiza_frame(self):
        ap = argparse.ArgumentParser()
        ap.add_argument("-v", "--video", required=True,
            help="rtsp://admin:@192.168.1.10:554/live/0/MAIN")
        args = vars(ap.parse_args())
        print("[INFO] starting video file thread...")
        fvs = FileVideoStream(args["video"]).start()
        time.sleep(1.0)
        # start the FPS timer
        fps = FPS().start()
        # loop over frames from the video file stream
        while fvs.more():
            frame = fvs.read()
            self.resized_cropped = cv2.resize(frame, (1024, 600))
            cv2.waitKey(1)
            fps.update()

This is the button that control de record:

def record_button(self):
        if self.is_recording_on:
            # inicia a gravação
            data = self.dataname()
            self.codec = cv2.VideoWriter_fourcc(*'mp4v')
            self.video_writer = cv2.VideoWriter(data+'.MP4', self.codec, 25, (self.frame_width, self.frame_height))
            self.thread_end = False
            self.rec = True

        else:
            # encerra a gravação
            self.rec = False
            self.thread_end = True

I suspect that my thread is writing frames too quickly, but I don't know how to solve this

EDIT: Based on the comments, i put a 'print("frame")' inside the 'while not self.thread_end'. I record a video during 5 seconds, and the output of 'frame' printed is: 30 print in 5 seconds of recording