从 RTSP 流捕获图像

Question

我想从 RTSP 摄像机流中提取帧，每分钟存储有时间戳和日期，持续 24 小时。我该怎么办？我的代码：

imagesFolder = "C:/Users/<user>/documents"
cap = cv2.VideoCapture("rtsp://username:password@cameraIP/axis-media/media.amp")
frameRate = cap.get(5) #frame rate
count = 0

while cap.isOpened():
    frameId = cap.get(1)  # current frame number
    ret, frame = cap.read()

    if (ret != True):
        break
    if (frameId % math.floor(frameRate) == 0):
        filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        cv2.imwrite(filename, frame)

    cap.release()
    print ("Done!")

cv2.destroyAllWindows()

Answer 1

您可以简单地在帧捕获之间等待 60 秒，并在 24*60 个周期后中断循环。

我尝试使用公共 RTSP 流测试我的代码，但出现黑帧，因此我无法测试我的代码。

这是代码：

import cv2
import time
from datetime import datetime
import getpass

#imagesFolder = "C:/Users/<user>/documents"

# https://stackoverflow.com/questions/842059/is-there-a-portable-way-to-get-the-current-username-in-python
imagesFolder = "C:/Users/" + getpass.getuser() + "/documents"

#cap = cv2.VideoCapture("rtsp://username:password@cameraIP/axis-media/media.amp")

# Use public RTSP Streaming for testing, but I am getting black frames!
cap = cv2.VideoCapture("rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov")
frameRate = cap.get(5) #frame rate
count = 0


while cap.isOpened():
    start_time = time.time()

    frameId = cap.get(1)  # current frame number
    ret, frame = cap.read()

    if (ret != True):
        break

    filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
    cv2.imwrite(filename, frame)

    # Show frame for testing
    cv2.imshow('frame', frame)
    cv2.waitKey(1)

    count += 1

    #Break loop after 24*60 minus
    if count > 24*60:
        break

    elapsed_time = time.time() - start_time

    # Wait for 60 seconds (subtract elapsed_time in order to be accurate).
    time.sleep(60 - elapsed_time)


cap.release()
print ("Done!")

cv2.destroyAllWindows()

---

更新：

上面的代码示例不起作用 - 第一帧每分钟重复一次。

建议的解决方案：

• 抓取所有视频帧，每分钟保存一帧。
  对于 5Hz 视频，一分钟的时间增量将精确到 0.2 秒。
• 使用单独的计时器测量 24 小时。

这是更新后的代码（从公共 RTSP 读取）：

import cv2
import time
from datetime import datetime
import getpass

imagesFolder = "C:/Users/" + getpass.getuser() + "/documents"
#cap = cv2.VideoCapture("rtsp://username:password@cameraIP/axis-media/media.amp")

# Use public RTSP Streaming for testing:
cap = cv2.VideoCapture("rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov")

#cap = cv2.VideoCapture("test2.mp4")
frameRate = cap.get(5) #frame rate

cur_time = time.time()  # Get current time

# start_time_24h measures 24 hours
start_time_24h = cur_time

# start_time_1min measures 1 minute
start_time_1min = cur_time - 59  # Subtract 59 seconds for start grabbing first frame after one second (instead of waiting a minute for the first frame).

while cap.isOpened():
    frameId = cap.get(1)  # current frame number
    ret, frame = cap.read()

    if (ret != True):
        break

    cur_time = time.time()  # Get current time
    elapsed_time_1min = cur_time - start_time_1min  # Time elapsed from previous image saving.

    # If 60 seconds were passed, reset timer, and store image.
    if elapsed_time_1min >= 60:
        # Reset the timer that is used for measuring 60 seconds
        start_time_1min = cur_time

        filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        #filename = "image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        cv2.imwrite(filename, frame)

        # Show frame for testing
        cv2.imshow('frame', frame)
        cv2.waitKey(1)

    elapsed_time_24h = time.time() - start_time_24h

    #Break loop after 24*60*60 seconds
    if elapsed_time_24h > 24*60*60:
        break

    #time.sleep(60 - elapsed_time) # Sleeping is a bad idea - we need to grab all the frames.


cap.release()
print ("Done!")

cv2.destroyAllWindows()

---

现在来自公共 RTSP 的图像看起来不错：

---

更新：

您可以尝试使用 FFmpeg（而不是 OpenCV）捕获视频流。

阅读以下博客：使用 FFMPEG 在 Python 中读取和写入视频帧

如果您使用的是 Windows 操作系统，请从此处下载最新的稳定 64 位静态版本（当前为 4.2.2）。
解压 zip 文件，并将

ffmpeg.exe

放在与 Python 脚本相同的文件夹中。

这里是代码（使用 FFmpeg 作为子进程和

stdout

作为

PIPE

进行捕获）：

import cv2
import time
from datetime import datetime
import getpass
import numpy as np
import subprocess as sp

imagesFolder = "C:/Users/" + getpass.getuser() + "/documents"
#cap = cv2.VideoCapture("rtsp://username:password@cameraIP/axis-media/media.amp")

# Use public RTSP Streaming for testing:
in_stream = "rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov"
cap = cv2.VideoCapture(in_stream)

#cap = cv2.VideoCapture("test2.mp4")
frameRate = cap.get(5) #frame rate

# Get resolution of input video
width  = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

# Release VideoCapture - it was used just for getting video resolution
cap.release()

#in_stream = "rtsp://xxx.xxx.xxx.xxx:xxx/Streaming/Channels/101?transportmode=multicast",

#Use public RTSP Streaming for testing
in_stream = "rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov"


# http://zulko.github.io/blog/2013/09/27/read-and-write-video-frames-in-python-using-ffmpeg/
FFMPEG_BIN = "ffmpeg" # on Linux ans Mac OS (also works on Windows when ffmpeg.exe is in the path)
#FFMPEG_BIN = "ffmpeg.exe" # on Windows

command = [ FFMPEG_BIN,
            '-i', in_stream,
            '-f', 'image2pipe',
            '-pix_fmt', 'bgr24',
            '-vcodec', 'rawvideo', '-an', '-']

# Open sub-process that gets in_stream as input and uses stdout as an output PIPE.
pipe = sp.Popen(command, stdout=sp.PIPE, bufsize=10**8)


cur_time = time.time()  # Get current time

# start_time_24h measures 24 hours
start_time_24h = cur_time

# start_time_1min measures 1 minute
start_time_1min = cur_time - 30  # Subtract 30 seconds for start grabbing first frame after 30 seconds (instead of waiting a minute for the first frame).



while True:
    # read width*height*3 bytes from stdout (= 1 frame)
    raw_frame = pipe.stdout.read(width*height*3)

    if len(raw_frame) != (width*height*3):
        print('Error reading frame!!!')  # Break the loop in case of an error (too few bytes were read).
        break

    cur_time = time.time()  # Get current time
    elapsed_time_1min = cur_time - start_time_1min  # Time elapsed from previous image saving.

    # If 60 seconds were passed, reset timer, and store image.
    if elapsed_time_1min >= 60:
        # Reset the timer that is used for measuring 60 seconds
        start_time_1min = cur_time

        # Transform the byte read into a numpy array, and reshape it to video frame dimensions
        frame = np.fromstring(raw_frame, np.uint8)
        frame = frame.reshape((height, width, 3))

        filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        #filename = "image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        cv2.imwrite(filename, frame)

        # Show frame for testing
        cv2.imshow('frame', frame)
        cv2.waitKey(1)

    elapsed_time_24h = time.time() - start_time_24h

    #Break loop after 24*60*60 seconds
    if elapsed_time_24h > 24*60*60:
        break

    #time.sleep(60 - elapsed_time) # Sleeping is a bad idea - we need to grab all the frames.


print ("Done!")

pipe.kill()  # Kill the sub-process after 24 hours
cv2.destroyAllWindows()

Answer 2

我尝试使用 apscheduler API 但没有成功。也许有人可以以不同的方式看待这个问题并使其发挥作用。

    import cv2
    import math
    import datetime
    from datetime import datetime
    from apscheduler.schedulers.blocking import BlockingScheduler


imagesFolder = "C:/Users/" + getpass.getuser() + "/documents"
cap = cv2.VideoCapture("rtsp://username:password@CameraIP/axis-media/media.amp")
frameRate = cap.get(5) #frame rate
count = 0




def some_job():
    while cap.isOpened():
        frameId = cap.get(1)
        ret, frame = cap.read()
        if (ret != True):
            break
        if (frameId % math.floor(frameRate) == 0):
                filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
                cv2.imwrite(filename, frame)
                scheduler = BlockingScheduler()
                scheduler.add_job(some_job, 'interval', seconds=60, start_date='2020-04-07 16:23:00', end_date='2020-04-08 16:23:00')
                scheduler.start()
        cap.release()
print ("Done!")
# Closes all the frames
cv2.destroyAllWindows()

Answer 3

这比其他解决方案效果更好。这里唯一的挑战是照片在前 3 分钟（前 3 张照片在几秒钟内拍摄，但在每分钟稍后保存）保存后停止保存。现在的解决方案是确保它在停止前长达 24 小时内节省每一分钟。

    import cv2
    import time
    import getpass
    import numpy as np
    import subprocess as sp
    from datetime import datetime

imagesFolder = "C:/Users/" + getpass.getuser() + "/documents"

# RTSP Streaming:
in_stream = "rtsp://username:password@cameraIP/axis-media/media.amp"
cap = cv2.VideoCapture(in_stream)

frameRate = cap.get(5) #frame rate

# Get resolution of input video
width  = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

# Release VideoCapture - it was used just for getting video resolution
cap.release()

in_stream = "rtsp://username:password@cameraIP/axis-media/media.amp"

FFMPEG_BIN = "ffmpeg.exe" # on Windows

# Suspecting camera supports TCP protocol hence added: '-rtsp_transport', 'tcp'
command = [ FFMPEG_BIN,
            '-rtsp_transport', 'tcp',
            '-i', in_stream,
            '-f', 'image2pipe',
            '-pix_fmt', 'bgr24',
            '-vcodec', 'rawvideo', '-an', '-']

# Open sub-process that gets in_stream as input and uses stdout as an output PIPE.
pipe = sp.Popen(command, stdout=sp.PIPE, bufsize=10**8)


cur_time = time.time()  # Get current time

# start_time_24h measures 24 hours
start_time_24h = cur_time

# start_time_1min measures 1 minute
start_time_1min = cur_time - 30  # Subtract 30 seconds for start grabbing first frame after 30 seconds (instead of waiting a minute for the first frame).



while True:
    # read width*height*3 bytes from stdout (= 1 frame)
    raw_frame = pipe.stdout.read(width*height*3)

    if len(raw_frame) != (width*height*3):
        print('Error reading frame!!!')  # Break the loop in case of an error (too few bytes were read).
        break

    cur_time = time.time()  # Get current time
    elapsed_time_1min = cur_time - start_time_1min  # Time elapsed from previous image saving.

    # If 60 seconds were passed, reset timer, and store image.
    if elapsed_time_1min >= 60:
        # Reset the timer that is used for measuring 60 seconds
        start_time_1min = cur_time

        # Transform the byte read into a numpy array, and reshape it to video frame dimensions
        frame = np.fromstring(raw_frame, np.uint8)
        frame = frame.reshape((height, width, 3))

        filename = imagesFolder + "/image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        #filename = "image_" + str(datetime.now().strftime("%d-%m-%Y_%I-%M-%S_%p"))  + ".jpg"
        cv2.imwrite(filename, frame)

        # Show frame for testing
        cv2.imshow('frame', frame)
        cv2.waitKey(1)

    elapsed_time_24h = time.time() - start_time_24h

    #Break loop after 24*60*60 seconds
    if elapsed_time_24h > 24*60*60:
        break

    #time.sleep(60 - elapsed_time) # Sleeping is a bad idea - we need to grab all the frames.


print ("Done!")

pipe.kill()  # Kill the sub-process after 24 hours
cv2.destroyAllWindows()