python - 是否可以将流保存在变量中？

问题描述

我正在尝试使用 Python 保存 10 秒的缓冲视频，特别是 '.h264' 格式。

为此，我一直在使用连接到 Raspberry Pi 的 PiCamera 和下面显示的脚本。我现在面临的主要障碍是，我不想将文件直接保存到一个位置 [stream.copy_to(str(time)+'.h264')] 我想将它保存到一个变量中以执行某些在最终保存之前进行操作（例如更改视频分辨率）。知道如何实现吗？

提前致谢！

import time
import io
import os 
import picamera
import datetime as dt
from PIL import Image
import cv2 

#obtain current time
def return_currentTime():
    return dt.datetime.now().strftime('%Y-%m-%d %H:%M:%S')

#trigger event declaration
def motion_detected():
    while True:
        print ("Trigger event(y)?")
        trigger = input ()
        if trigger =="y":
            time = return_currentTime()
            print ("Buffering...")
            stream.copy_to(str(time)+'.h264')           
           
        else: 
           camera.stop_recording()
           break
        
#countdown timer 
def countdown (t):
    while t:
        mins, secs = divmod (t,60)
        timer = '{:02d}:{:02d}'.format(mins, secs)
        print(timer, end="\r")
        time.sleep(1)
        t-=1
    print('Buffer available!')
   

camera = picamera.PiCamera()

camera.resolution = (640, 480)

stream = picamera.PiCameraCircularIO(camera, seconds = 5)

#code will work using h264 as format
camera.start_recording (stream, format = 'h264')
countdown(5)
motion_detected()

标签： pythonimageopencvstreamcamera

我没有 Raspberry Pi，但我知道如何做到这一点。

我使用VideoStream了它也支持PiCamera，所以你可以使用下面的代码。

stream = VideoStream(usePiCamera=False,
                 resolution=(640, 480),
                 framerate=32).start()

# Wait for a two-second for warming the webcam.
time.sleep(2.0)

开始获取帧

while True:
    frame = stream.read()
    countdown(5)
    motion_detected()

修改motion_detected()以保存帧。

while True:
    frame = stream.read()
    countdown(5)
    motion_detected(frame)

现在我们需要使用array或来存储帧dictionary。

字典比数组快。（来源）

我们需要在项目文件之上初始化一个全局字典。

import time
import datetime as dt
from imutils.video import VideoStream

dictionary = {}
count = 0

我们需要修改motion_detected方法，我们先初始化入参
```
# trigger event declaration
def motion_detected(input_frame):
```

二、我们在里面定义全局变量motion_detected

# trigger event declaration
def motion_detected(input_frame):
    global dictionary
    global count

不幸的是， VideoStream 对象没有copy_to属性，因此我必须直接将帧分配给字典：

def motion_detected(input_frame):
    global dictionary
    global count
    while True:
        print("Trigger event(y)?")
        trigger = input()
        if trigger == "y":
            current_time = return_current_time()
            print("Buffering...")
            # stream.copy_to(str(current_time) + '.h264')
            dictionary[count] = input_frame
            count += 1
            if count == 10:
                print("\n10 frames are stored\n")
         else:
             stream.stop()
     break

现在我们可以执行某些操作，例如检测边缘。

while True:
    frame = stream.read()
    countdown(5)
    motion_detected(frame)

    for stored_frame in dictionary.values():
        result = cv2.Canny(image=stored_frame,
                           threshold1=50,
                           threshold2=100)

1. 输出：

保存帧

要保存帧，您需要枚举存储的帧。

for count, stored_frame in enumerate(dictionary.values()):

然后，应用您的操作：

for count, stored_frame in enumerate(dictionary.values()):
    result = cv2.Canny(image=stored_frame,
                       threshold1=50,
                       threshold2=100)

将其保存到文件夹中。

 for count, stored_frame in enumerate(dictionary.values()):
     result = cv2.Canny(image=stored_frame,
                        threshold1=50,
                        threshold2=100)

      cv2.imwrite("output/frame_{}.png".format(count), result)

如果你想循环多次，上面的代码是行不通的。在这种情况下，您需要在循环之上初始化while循环。

counter = 0

while True:
    frame = stream.read()
    countdown(5)
    motion_detected(frame)

    for stored_frame in dictionary.values():
        result = cv2.Canny(image=stored_frame,
                           threshold1=50,
                           threshold2=100)

        cv2.imwrite("output/frame_{}.png".format(counter), result)
     counter += 1

代码：

import cv2
import time
import datetime as dt
from imutils.video import VideoStream

dictionary = {}
count = 0


# obtain current time
def return_current_time():
    return dt.datetime.now().strftime('%Y-%m-%d %H:%M:%S')


# trigger event declaration
def motion_detected(input_frame):
    global dictionary
    global count
    while True:
        print("Trigger event(y)?")
        trigger = input()
        if trigger == "y":
            current_time = return_current_time()
            print("Buffering...")
            # stream.copy_to(str(current_time) + '.h264')
            dictionary[count] = input_frame
            count += 1
            if count == 10:
                print("\n10 frames are stored\n")
        else:
            stream.stop()
            break


# countdown timer
def countdown(t):
    while t:
        mins, secs = divmod(t, 60)
        timer = '{:02d}:{:02d}'.format(mins, secs)
        print(timer, end="\r")
        time.sleep(1)
        t -= 1
    print('Buffer available!')


stream = VideoStream(usePiCamera=False,
                     resolution=(640, 480),
                     framerate=32).start()

time.sleep(2.0)

counter = 0

while True:
    frame = stream.read()
    countdown(5)
    motion_detected(frame)

    for stored_frame in dictionary.values():
        result = cv2.Canny(image=stored_frame,
                           threshold1=50,
                           threshold2=100)

        cv2.imwrite("output/frame_{}.png".format(counter), result)
        counter += 1

python - 是否可以将流保存在变量中？

问题描述

解决方案

推荐阅读