cap = cv2.VideoCapture("D:\Desktop\VID_20230414_113545.mp4")

这是使用 OpenCV 库中的 VideoCapture 类来读取本地视频文件 "D:\Desktop\VID_20230414_113545.mp4" 的代码。可以通过 cap.read() 方法一帧一帧地读取视频帧。要注意的是，若视频文件路径中有反斜杠 "\"，需要用双反斜杠 "\\" 或单斜杠 "/" 来转义，否则会报错。

相关问题

cap = cv2.VideoCapture(video_file) frameCount = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) fps = int(cap.get(cv2.CAP_PROP_FPS))

当你使用OpenCV的VideoCapture对象`cv2.VideoCapture(video_file)`打开视频文件时，你可以通过调用`.get()`方法来获取视频的相关信息。其中，`cv2.CAP_PROP_FRAME_COUNT`属性返回视频的总帧数，而`cv2.CAP_PROP_FPS`则返回视频的帧率（每秒播放的帧数）。

下面是如何演示这两个操作的示例：

import cv2

# 初始化VideoCapture对象
cap = cv2.VideoCapture(video_file)

# 获取视频的帧总数
frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
print(f"视频总帧数: {frame_count}")

# 获取视频的帧率
fps = int(cap.get(cv2.CAP_PROP_FPS))
print(f"视频帧率: {fps} frames per second")

# 关闭VideoCapture对象
cap.release()

请注意，在上述代码中，如果遇到获取帧率错误，可能是因为`cv2.CAP_PROP_POS_MSEC`这个枚举值被误用了[^2]。如果你需要获取视频的持续时间（以毫秒为单位），应该使用`cv2.CAP_PROP_POS_MSEC`，而不是`cv2.CAP_PROP_FPS`。

import timefrom serial import Serialimport serial.tools.list_portsimport cv2import numpy as npcap1 = cv2.VideoCapture("/Users/yankaipan/Desktop/stand.mp4")cap2 = cv2.VideoCapture("/Users/yankaipan/Desktop/apple.mp4")cap3 = cv2.VideoCapture("/Users/yankaipan/Desktop/bamboo.mp4")cap4 = cv2.VideoCapture("/Users/yankaipan/Desktop/rubbish.mp4")port_list = list(serial.tools.list_ports.comports())port_list_1 = list(port_list[2])port_serial = port_list_1[0]arduinoData = serial.Serial(port_serial, 9600)time.sleep(1)while True: while (arduinoData.inWaiting() == 0): pass dataPacket = arduinoData.readline() dataPacket = dataPacket.decode().strip() print(dataPacket) time.sleep(3) if dataPacket == "a": while cap1.isOpened(): ret, frame = cap1.read() if ret == True: cv2.imshow('Frame', frame) if cv2.waitKey(25) & 0xFF == ord('q'): break else: cap1.set(cv2.CAP_PROP_POS_FRAMES, 0) elif dataPacket == "b": while cap2.isOpened(): ret, frame = cap2.read() if ret == True: cv2.imshow('Frame', frame) if cv2.waitKey(25) & 0xFF == ord('q'): break else: cap2.set(cv2.CAP_PROP_POS_FRAMES, 0) elif dataPacket == "c": while cap3.isOpened(): ret, frame = cap3.read() if ret == True: cv2.imshow('Frame', frame) if cv2.waitKey(25) & 0xFF == ord('q'): break else: cap3.set(cv2.CAP_PROP_POS_FRAMES, 0) elif dataPacket == "d": while cap4.isOpened(): ret, frame = cap4.read() if ret == True: cv2.imshow('Frame', frame) if cv2.waitKey(25) & 0xFF == ord('q'): break else: cap4.set(cv2.CAP_PROP_POS_FRAMES, 0)cv2.destroyAllWindows()怎样修改代码能够在其中一个a视频播放时，接收到arduino发送的消息时能够触发另一视频b或c或d并播放？

可以使用一个变量来记录当前正在播放的视频，当接收到新的消息时，根据消息内容判断应该播放哪个视频，并将当前正在播放的视频暂停或关闭，然后切换到新的视频播放。

以下是修改后的代码：

import time
from serial import Serial
import serial.tools.list_ports
import cv2
import numpy as np

cap1 = cv2.VideoCapture("/Users/yankaipan/Desktop/stand.mp4")
cap2 = cv2.VideoCapture("/Users/yankaipan/Desktop/apple.mp4")
cap3 = cv2.VideoCapture("/Users/yankaipan/Desktop/bamboo.mp4")
cap4 = cv2.VideoCapture("/Users/yankaipan/Desktop/rubbish.mp4")

port_list = list(serial.tools.list_ports.comports())
port_list_1 = list(port_list[2])
port_serial = port_list_1[0]
arduinoData = serial.Serial(port_serial, 9600)

time.sleep(1)

current_video = None  # 记录当前正在播放的视频

while True:
    while (arduinoData.inWaiting() == 0):
        pass
    dataPacket = arduinoData.readline()
    dataPacket = dataPacket.decode().strip()
    print(dataPacket)
    time.sleep(3)
    
    if dataPacket == "a":
        if current_video != cap1:  # 判断是否需要切换视频
            if current_video is not None:
                current_video.release()
            current_video = cap1
        while current_video.isOpened():
            ret, frame = current_video.read()
            if ret == True:
                cv2.imshow('Frame', frame)
                if cv2.waitKey(25) & 0xFF == ord('q'):
                    break
            else:
                current_video.set(cv2.CAP_PROP_POS_FRAMES, 0)
                
    elif dataPacket == "b":
        if current_video != cap2:
            if current_video is not None:
                current_video.release()
            current_video = cap2
        while current_video.isOpened():
            ret, frame = current_video.read()
            if ret == True:
                cv2.imshow('Frame', frame)
                if cv2.waitKey(25) & 0xFF == ord('q'):
                    break
            else:
                current_video.set(cv2.CAP_PROP_POS_FRAMES, 0)
                
    elif dataPacket == "c":
        if current_video != cap3:
            if current_video is not None:
                current_video.release()
            current_video = cap3
        while current_video.isOpened():
            ret, frame = current_video.read()
            if ret == True:
                cv2.imshow('Frame', frame)
                if cv2.waitKey(25) & 0xFF == ord('q'):
                    break
            else:
                current_video.set(cv2.CAP_PROP_POS_FRAMES, 0)
                
    elif dataPacket == "d":
        if current_video != cap4:
            if current_video is not None:
                current_video.release()
            current_video = cap4
        while current_video.isOpened():
            ret, frame = current_video.read()
            if ret == True:
                cv2.imshow('Frame', frame)
                if cv2.waitKey(25) & 0xFF == ord('q'):
                    break
            else:
                current_video.set(cv2.CAP_PROP_POS_FRAMES, 0)

cv2.destroyAllWindows()

注意，在切换视频时需要将上一个视频释放掉，否则会导致内存泄漏。