从摄像机录制视频时节省TTL脉冲输入时间

Question

I am recording video using Raspicam on raspberry pi and saving the video buffer as well as timestamp for each frame using the following script:

import io
import time
import datetime as dt
from picamera import PiCamera
from threading import Thread, Event
from queue import Queue, Empty
import sys, getopt
import argparse

WIDTH  = 640
HEIGHT = 480
FRAMERATE = 30
VIDEO_STABILIZATION = True
EXPOSURE_MODE = 'night'
BRIGHTNESS = 55
CONTRAST = 50
SHARPNESS = 50
SATURATION = 30
AWB_MODE = 'off'
AWB_GAINS = 1.4

VIDEO_FILE_NAME = "cam3_output_" + str(dt.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")) + ".h264"
TIMESTAMP_FILE_NAME = "cam3_timestamp_" + str(dt.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")) + ".csv"
runningTimeHours, runningTimeMinutes, runningTimeSeconds = 0,0,0

class VideoOutput(Thread):
    def __init__(self, filename):
        super(VideoOutput, self).__init__()
        self._output = io.open(filename, 'wb', buffering=0)
        self._event = Event()
        self._queue = Queue()
        self.start()

    def write(self, buf):
        self._queue.put(buf)
        return len(buf)

    def run(self):
        while not self._event.wait(0):
            try:
                buf = self._queue.get(timeout=0.1)
            except Empty:
                pass
            else:
                self._output.write(buf)
                self._queue.task_done()

    def flush(self):
        self._queue.join()
        self._output.flush()

    def close(self):
        self._event.set()
        self.join()
        self._output.close()

    @property
    def name(self):
        return self._output.name


class TimestampOutput(object):
    def __init__(self, camera, video_filename, timestamp_filename):
        self.camera = camera
        self._video = VideoOutput(video_filename)
        self._timestampFile = timestamp_filename
        self._timestamps = []

    def write(self, buf):
        if self.camera.frame.complete and self.camera.frame.timestamp is not None:
            self._timestamps.append((
                self.camera.frame.timestamp,
                self.camera.dateTime,
                self.camera.clockRealTime
                ))
        return self._video.write(buf)

    def flush(self):
        with io.open(self._timestampFile, 'w') as f:
            f.write('GPU Times, time.time(), clock_realtime\n')
            for entry in self._timestamps:
                f.write('%d,%f,%f\n' % entry)

    def close(self):
        self._video.close()

parser = argparse.ArgumentParser()
parser.add_argument("-hr", "--hours", type=int, help="number of hours to record")
parser.add_argument("-m", "--minutes", type=int, help="number of minutes to record")
parser.add_argument("-s", "--seconds", type=int, help="number of seconds to record")
args = parser.parse_args()


runningTimeHours = float(args.hours)
runningTimeMinutes = float(args.minutes)
runningTimeSeconds = float(args.seconds)

totalRunningTime = runningTimeHours*60*60 + runningTimeMinutes*60 + runningTimeSeconds

with PiCamera(resolution=(WIDTH, HEIGHT), framerate=FRAMERATE) as camera:
    camera.brightness = BRIGHTNESS
    camera.contrast = CONTRAST
    camera.sharpness = SHARPNESS
    camera.video_stabilization = VIDEO_STABILIZATION
    camera.hflip = False
    camera.vflip = False

    #warm-up time to camera to set its initial settings
    time.sleep(2)

    camera.exposure_mode = EXPOSURE_MODE
    camera.awb_mode = AWB_MODE
    camera.awb_gains = AWB_GAINS

    #time to let camera change parameters according to exposure and AWB
    time.sleep(2)

    #switch off the exposure since the camera has been set now 
    camera.exposure_mode = 'off'

    output = TimestampOutput(camera, VIDEO_FILE_NAME, TIMESTAMP_FILE_NAME)
    try:
        camera.start_preview()
        # Construct an instance of our custom output splitter with a filename  and a connected socket
        print('Starting Recording')
        camera.start_recording(output, format='h264')
        print('Started Recording')
        camera.wait_recording(totalRunningTime)
        camera.stop_recording()
        camera.stop_preview()
        print('Recording Stopped')
    except KeyboardInterrupt:
        print('Closing Output File')
        sys.exit(2)
    finally:
        output.close()
        print('Output File Closed')

Simultaneously while this recording is going on, I am sending TTL pulse to GPIO pin 4. I now want to add a code block to the above script so that for each TTL HIGH input received I can save the corresponding time value in a file.

Something like this without camera running script involved:

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
pinTTL = 4

GPIO.setup(pinTTL, GPIO.IN)

while True:
    count = 0
    inputState = GPIO.input(pinTTL)
    if inputState == True:
        print 'HIGH', time.time()

GPIO.cleanup()

The above script for pin state set to HIGH saves the time.time() value.

Basically I want to integrate the 2 scripts mentioned. I tried creating another thread to save time.time() values according to TTL input in the same way I am saving video buffer but couldn't get it to work.

Thanks for the help.

Answer 1

Below script works for me. The add_event_callback automatically creates a separate thread for handling GPIO event changes. This allows to call any function as separate thread and log the TTL timestmaps simultaneously.

#import the necessary modules
import io
import time
import datetime as dt
from picamera import PiCamera
from threading import Thread, Event
from queue import Queue, Empty
import sys, getopt
import argparse
import RPi.GPIO as GPIO

#camera parameter setting
WIDTH  = 640
HEIGHT = 480
FRAMERATE = 30
VIDEO_STABILIZATION = True
EXPOSURE_MODE = 'night'
BRIGHTNESS = 55
CONTRAST = 50
SHARPNESS = 50
SATURATION = 30
AWB_MODE = 'off'
AWB_GAINS = 1.4

#video, timestamps and ttl file name
VIDEO_FILE_NAME = "cam4_output_" + str(dt.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")) + ".h264"
TIMESTAMP_FILE_NAME = "cam4_timestamp_" + str(dt.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")) + ".csv"
TTL_FILE_NAME = "cam4_ttl_" + str(dt.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")) + ".csv"

#running time variable intialization
runningTimeHours, runningTimeMinutes, runningTimeSeconds = 0,0,0

#set raspberry pi board layout to BCM
GPIO.setmode(GPIO.BCM)
#pin number to receive TTL input
pinTTL = 4
#set the pin as input pin
GPIO.setup(pinTTL, GPIO.IN)
#add event detection script to GPIO pin
GPIO.add_event_detect(pinTTL, GPIO.BOTH)

#video output thread to save video file
class VideoOutput(Thread):
    def __init__(self, filename):
        super(VideoOutput, self).__init__()
        self._output = io.open(filename, 'wb', buffering=0)
        self._event = Event()
        self._queue = Queue()
        self.start()

    def write(self, buf):
        self._queue.put(buf)
        return len(buf)

    def run(self):
        while not self._event.wait(0):
            try:
                buf = self._queue.get(timeout=0.1)
            except Empty:
                pass
            else:
                self._output.write(buf)
                self._queue.task_done()

    def flush(self):
        self._queue.join()
        self._output.flush()

    def close(self):
        self._event.set()
        self.join()
        self._output.close()

    @property
    def name(self):
        return self._output.name

#timestamp output object to save timestamps according to pi and TTL inputs received and write to file
class TimestampOutput(object):
    def __init__(self, camera, video_filename, timestamp_filename, ttl_filename):
        self.camera = camera
        self._video = VideoOutput(video_filename)
        self._timestampFile = timestamp_filename
        self._ttlFile = ttl_filename
        self._timestamps = []
        self._ttlTimestamps = []

    def ttlTimestampsWrite(self, input_pin):
        try:
            inputState = GPIO.input(input_pin)
            self._ttlTimestamps.append((inputState, self.camera.frame.timestamp, self.camera.dateTime, self.camera.clockRealTime))
            print(self.camera.frame.timestamp)
        except Exception as e:
            print(str(e))
            pass

    def write(self, buf):
        if self.camera.frame.complete and self.camera.frame.timestamp is not None:
            self._timestamps.append((
                self.camera.frame.timestamp,
                self.camera.dateTime,
                self.camera.clockRealTime
                ))
        return self._video.write(buf)

    def flush(self):
        with io.open(self._timestampFile, 'w') as f:
            f.write('GPU Times, time.time(), clock_realtime\n')
            for entry in self._timestamps:
                f.write('%d,%f,%f\n' % entry)
        with io.open(self._ttlFile, 'w') as f:
            f.write('Input State, GPU Times, time.time(), clock_realtime\n')
            for entry in self._ttlTimestamps:
                f.write('%f,%f,%f,%f\n' % entry)

    def close(self):
        self._video.close()

parser = argparse.ArgumentParser()
parser.add_argument("-hr", "--hours", type=int, help="number of hours to record")
parser.add_argument("-m", "--minutes", type=int, help="number of minutes to record")
parser.add_argument("-s", "--seconds", type=int, help="number of seconds to record")
args = parser.parse_args()

runningTimeHours = float(args.hours)
runningTimeMinutes = float(args.minutes)
runningTimeSeconds = float(args.seconds)

totalRunningTime = runningTimeHours*60*60 + runningTimeMinutes*60 + runningTimeSeconds

with PiCamera(resolution=(WIDTH, HEIGHT), framerate=FRAMERATE) as camera:
    camera.brightness = BRIGHTNESS
    camera.contrast = CONTRAST
    camera.sharpness = SHARPNESS
    camera.video_stabilization = VIDEO_STABILIZATION
    camera.hflip = False
    camera.vflip = False

    #warm-up time to camera to set its initial settings
    time.sleep(2)

    camera.exposure_mode = EXPOSURE_MODE
    camera.awb_mode = AWB_MODE
    camera.awb_gains = AWB_GAINS

    #time to let camera change parameters according to exposure and AWB
    time.sleep(2)

    #switch off the exposure since the camera has been set now
    camera.exposure_mode = 'off'

    output = TimestampOutput(camera, VIDEO_FILE_NAME, TIMESTAMP_FILE_NAME, TTL_FILE_NAME)
    GPIO.add_event_callback(pinTTL, output.ttlTimestampsWrite)
    try:
        camera.start_preview()
        # Construct an instance of our custom output splitter with a filename  and a connected socket
        print('Starting Recording')
        camera.start_recording(output, format='h264')
        print('Started Recording')
        camera.wait_recording(totalRunningTime)
        camera.stop_recording()
        camera.stop_preview()
        print('Recording Stopped')
    except KeyboardInterrupt:
        print('Closing Output File')
        sys.exit(2)
    except:
        output.close()
        print('exception! output file closed')
    finally:
        output.close()
        print('Output File Closed')