【opencv】视频流的读取

1，截取视频，抽帧&&快速抽帧

# -*- coding: utf-8 -*-
import cv2 as cv

def calcute(minute, second, fps):
    return minute * fps * 60 + second * fps

def cut_video(src, dst, start, end):
    # 读取视频
    video = cv.VideoCapture(src)
    fps = video.get(cv.CAP_PROP_FPS)  # 帧率，每秒多少帧
    minute = int(fps) * 60  # 每分钟的帧数

    # 保存视频
    fourcc = cv.VideoWriter_fourcc(*'XVID')  # 保存视频的编码
    out = cv.VideoWriter(dst, fourcc, fps, (1920, 1080))

    # 读取视频
    i = 0
    while (video.isOpened()):
        ret, frame = video.read()  # 读取图片

        # 读取区间
        if start <= i and i <= end:  # 区间内
            out.write(frame)

        # 显示分钟数
        if i % minute == 0:
            now_minute = i // minute
            print("pass {} minutes".format(now_minute))

        if not ret:  # 条件终止
            break

        i += 1  # 遍历视频

    video.release()
    out.release()
    
    # 方法二，快
    i = 0
    while (video.isOpened()):
        ret = video.grab()
        # 每个5帧取一帧
        if i % int(fps) == 0:
            ret, frame = video.retrieve()
        
        i += 1




if __name__ == '__main__':
    src = r"D:1.mp4"
    dst = r"D:videocut_video1.mp4"
    start = calcute(minute=24, second=27, fps=25)
    end = calcute(minute=29, second=0, fps=25)

    cut_video(src, dst, start, end)

2，截图图片

# -*- coding: utf-8 -*-
import cv2 as cv
import os

def cut_video(src, dst, index):
    # 读取视频
    video = cv.VideoCapture(src)
    fps = video.get(cv.CAP_PROP_FPS)  # 帧率，每秒多少帧
    minute = int(fps) * 60  # 每分钟的帧数

    # 读取视频
    i = 0 # 视频索引
    while (video.isOpened()):
        ret, frame = video.read()  # 读取图片

        # 读取视频
        if i % 25 == 0:  # 区间内，每5帧取一帧
            img_path = dst + "/{}.jpg".format(index)
            print(img_path)
            cv.imwrite(img_path, frame, [int(cv.IMWRITE_JPEG_QUALITY), 95])  # 默认95
            index += 1  # 增加图片索引

        if not ret:  # 条件终止
            break
        i += 1 # 视频索引

    video.release()

    return index

def video2jpg(src, dst, index=0):
    # 读取视频文件
    for file in os.listdir(src):
        full_path = src + "/" + file

        # 视频 -> jpg
        index = cut_video(full_path, dst, index)
        index += 1



if __name__ == '__main__':
    src = r"D:datacuttedday02"
    dst = r"D:day02" # 保存路径不能出现中文字符
    index = 0

    # 将文件里所有视频转为图片
    video2jpg(src, dst, index)

3.获取视频流格式

def get_video_format(fourcc):
    decoded_codec_format = chr(fourcc & 0xFF) + chr((fourcc & 0xFF00) >> 8) + 
                            chr((fourcc & 0xFF0000) >> 16) + chr((fourcc & 0xFF000000) >> 24)
    return decoded_codec_format

four = cap.get(cv2.CAP_PROP_FOURCC)
fourcc = get_video_format(int(four))

4.ffmpeg

ffmpeg读取视频流

最后

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