现在要对一个视频文件提取关键帧等信息用来做预览图。
图中应当包含 文件名、大小、分辨率、视频时长以及8张截图。
拟选用opencv(主要) + PIL(用于图片添加中文)来加以实现。
成果预览
先放截图。
常见的坑
库的安装问题
原始的源在国内不太行，需要使用镜像：
清华：https://pypi.tuna.tsinghua.edu.cn/simple
阿里云：http://mirrors.aliyun.com/pypi/simple/
中国科技大学 https://pypi.mirrors.ustc.edu.cn/simple/
华中理工大学：http://pypi.hustunique.com/
山东理工大学：http://pypi.sdutlinux.org/
豆瓣：http://pypi.douban.com/simple/
图片加入中文乱码问题
本来直接调用opencv的方法，但是不支持中文字符，只能cv转为PIL再加入字符再转为cv
def imgAddText(img, text, xOffset = 0, yOffset = 0):
#cv2.putText(图像,需要添加字符串,需要绘制的坐标,字体类型,字号,字体颜色,字体粗细)
img2 = cv2.putText(img, text, (xOffset, yOffset), cv2.LINE_AA, 0.7, (249, 249, 249), 2)
return img2
def imgAddTextUTF8(img, text, xOffset = 0, yOffset = 0):
img_cv2_RGB = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) # cv2和PIL中颜色的hex码的储存顺序不同
img_PIL = Image.fromarray(img_cv2_RGB)
draw = ImageDraw.Draw(img_PIL)
font = ImageFont.truetype("simhei.ttf", 20, encoding="utf-8") # 参数1：字体文件路径，参数2：字体大小
draw.text((xOffset, yOffset), text, (0, 0, 0), font=font) # 参数1：打印坐标，参数2：文本，参数3：字体颜色，参数4：字体
# PIL图片转cv2 图片
img_cv2_textAdded = cv2.cvtColor(np.array(img_PIL), cv2.COLOR_RGB2BGR)
return img_cv2_textAdded
截图时的效率问题
网上搜了一下，大多是逐帧读取并计数，文件很大的时候需要几十分钟甚至以小时计。low B代码如下：
#...省略
cutTimes = [10,600,1200, 2400] #在第10, 600,1200,2400秒进行截图
cutFrames = [int(info["rate"] * x) + 1 for x in cutTimes ]
print("cutFrames:", cutFrames)
cap = cv2.VideoCapture(file_path)
frame_count = 1
cut_cnt = 0
while(True):
ret, frame = cap.read()
if ret:
if frame_count == cutFrames[cut_cnt]:
t_frames.append( (cutTimes[cut_cnt], frame) )
cut_cnt += 1
print("开始截取视频第：" + str(cut_cnt) + " 帧")
frame_count += 1
if cut_cnt >= len(cutFrames):
break
#cv2.waitKey(0)
else:
print("所有帧都已经保存完成")
break
但是，实际上可以人为设置读取帧的位置，没必要一帧一帧的读：
#...省略
cutTimes = [10,600,1200, 2400] #在第10, 600,1200,2400秒进行截图
cutFrames = [int(info["rate"] * x) + 1 for x in cutTimes ]
print("cutFrames:", cutFrames)
cap = cv2.VideoCapture(file_path)
cut_cnt = 0
for cutFrame in cutFrames:
cap.set(cv2.CAP_PROP_POS_FRAMES,cutFrame -1)
ret, frame = cap.read()
if ret:
t_frames.append( (cutTimes[cut_cnt], frame) )
cut_cnt += 1
print("截取视频第：" + str(cut_cnt) + " 帧")
else:
break
相关库的安装
pip install opencv-python -i https://pypi.tuna.tsinghua.edu.cn/simple
pip install pillow -i https://pypi.tuna.tsinghua.edu.cn/simple
相关代码
默认是根据时长均匀抽取 8张截图，将每张截图重新等比拉伸为宽480的图像，并且打上时间戳。
相关间隔参数可以在mp4toJpg方法里改改。
因为是自用，也就没怎么封装了。
import cv2
import os
import numpy as np
import math
from PIL import Image, ImageDraw, ImageFont
def getInfo(file_path):
info = {}
filepath, filename = os.path.split(file_path)
info["name"] = filename
if os.path.exists(file_path):
info["size"] = os.path.getsize(file_path)
info["sizeUnit"] = sizeConvert(info["size"])
cap = cv2.VideoCapture(file_path)
if cap.isOpened():
# get方法参数按顺序对应下表（从0开始编号)
rate = cap.get(5) # 帧速率
frame_number = cap.get(7) # 视频文件的帧数
info["rate"] = rate
info["duration"] = int(frame_number / rate)
info["durationHMS"] = timeConvert(info["duration"])
info["width"]=int(cap.get(3))
info["height"]=int(cap.get(4))
cap.release()
return info
def getFrames(file_path, cutTimes):
'''
file_path: 文件名
cutTimes： 抽取帧的时间数组，时间单位为s
return [时间, 帧图像]数组
'''
t_frames = []
info = getInfo(file_path)
cutFrames = [int(info["rate"] * x) + 1 for x in cutTimes ]
print("cutFrames:", cutFrames)
cap = cv2.VideoCapture(file_path)
cut_cnt = 0
for cutFrame in cutFrames:
cap.set(cv2.CAP_PROP_POS_FRAMES,cutFrame -1)
ret, frame = cap.read()
if ret:
t_frames.append( (cutTimes[cut_cnt], frame) )
cut_cnt += 1
print("截取视频第：" + str(cut_cnt) + " 帧")
else:
break
cap.release()
return t_frames
def timeConvert(seconds, str = True):
h = seconds // 3600
m = seconds % 3600 // 60
s = seconds % 60
if str:
if h > 0:
return '{:.0f}:{:.0f}:{:.0f}'.format(h, m, s)
else:
return '{:.0f}:{:.0f}s'.format(m, s)
else:
return h, m, s
def sizeConvert(size):# 单位换算
K, M, G = 1024, 1024**2, 1024**3
if size >= G:
return str(size//G)+'GB'
elif size >= M:
return str(size//M)+'MB'
elif size >= K:
return str(size//K)+'KB'
else:
return str(size)+'Bytes'
def imgResize(img, width = 1980):
'''
将图片等比拉伸至宽为width
'''
h, w = img.shape[:2]
height = int(h * width / w)
if width > w:#放大图像
img_new = cv2.resize(img, (width, height), interpolation=cv2.INTER_CUBIC)
else:
img_new = cv2.resize(img, (width, height), interpolation=cv2.INTER_AREA)
return img_new
def imgAddImg(imgDst, imgSrc, xOffset = 0, yOffset = 0, copy = False):
if copy:
imgDst = imgDst.copy()
imgDst[yOffset:yOffset+imgSrc.shape[0], xOffset:xOffset+imgSrc.shape[1]] = imgSrc
return imgDst
def imgAddText(img, text, xOffset = 0, yOffset = 0):
#cv2.putText(图像,需要添加字符串,需要绘制的坐标,字体类型,字号,字体颜色,字体粗细)
img2 = cv2.putText(img, text, (xOffset, yOffset), cv2.LINE_AA, 0.7, (249, 249, 249), 2)
return img2
def imgAddTextUTF8(img, text, xOffset = 0, yOffset = 0):
img_cv2_RGB = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) # cv2和PIL中颜色的hex码的储存顺序不同
img_PIL = Image.fromarray(img_cv2_RGB)
draw = ImageDraw.Draw(img_PIL)
font = ImageFont.truetype("simhei.ttf", 20, encoding="utf-8") # 参数1：字体文件路径，参数2：字体大小
draw.text((xOffset, yOffset), text, (0, 0, 0), font=font) # 参数1：打印坐标，参数2：文本，参数3：字体颜色，参数4：字体
# PIL图片转cv2 图片
img_cv2_textAdded = cv2.cvtColor(np.array(img_PIL), cv2.COLOR_RGB2BGR)
return img_cv2_textAdded
def imgWhite(height, width):
height = int(height)
width = int(width)
img = np.zeros((height,width), dtype=np.uint8)
#img = np.zeros((height,width,3), dtype=np.uint8)
img = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)
img[:,:,:] = 255
return img
def mp4toJpg(f_video, f_img):
#start = cv2.getTickCount()
small_pic_width = 480
small_pic_cnt = 8
small_pic_per_line = 2
small_pic_gap_x = 5
small_pic_gap_y = 5
small_pic_top = 120
small_pic_bottom = 5
small_pic_left = 5
small_pic_right = 5
time_reduce = 5
# 获取信息
info = getInfo(f_video)
# 提取图像
period = int( (info["duration"] - time_reduce) // small_pic_cnt )
cutTimes = [ period*i for i in range(small_pic_cnt) ]
t_imgs = getFrames(f_video, cutTimes)
small_pic_cnt = len(t_imgs)
# 对图像进行缩放，添加时间戳水印
imgs_fixed = []
h, w = (0,0)
for time, img in t_imgs:
#print(r"正在加工图片%d"%time)
img_resize = imgResize(img, small_pic_width)
img_add_time = imgAddText(img_resize, timeConvert(time), 10, 25)
h, w = img_add_time.shape[:2]
#cv2.imwrite(str(time) + "_time.png", img_add_time)
imgs_fixed.append(img_add_time)
# 先画一张空白图
height = small_pic_top + small_pic_bottom + (math.ceil(small_pic_cnt*1.0/small_pic_per_line)) *(small_pic_gap_y + h) - small_pic_gap_y
width = small_pic_left + small_pic_right + small_pic_per_line *(small_pic_gap_x + w) - small_pic_gap_x
img_backgroud = imgWhite(height, width)
# print("height = %.0f, width = %.0f"%(height,width))
# print("h = %.0f, w = %.0f"%(h,w))
# 在大图上加入视频信息
filepath, filename = os.path.split(f_video)
img_backgroud = imgAddTextUTF8(img_backgroud, "视频名称: %s"%filename, 20, 20)
img_backgroud = imgAddTextUTF8(img_backgroud, "视频时长: %s"%info["durationHMS"], 20, 45)
img_backgroud = imgAddTextUTF8(img_backgroud, "视频大小: %s"%(info["sizeUnit"]), 20, 70)
img_backgroud = imgAddTextUTF8(img_backgroud, "分辨率: %dx%d"%(info["width"],info["height"]), 20, 95)
# 在大图上加入视频截图
i = 0
while i < small_pic_cnt:
xx = i%small_pic_per_line
yy = int(i/small_pic_per_line)
#print(r"正在将第(%d,%d)放入背景"%(xx+1, yy+1))
off_x = int(small_pic_left + (small_pic_gap_x + w)*xx)
off_y = int(small_pic_top + (small_pic_gap_y + h)*yy)
img_backgroud = imgAddImg(img_backgroud, imgs_fixed[i], off_x, off_y)
#imgAddImg(img_backgroud, img_backgroud, 0, 0)
i+=1
#end = cv2.getTickCount()
#time_spent = (end-start)/ cv2.getTickFrequency()/60
#print("耗时%.1f min"%time_spent)
cv2.imwrite(f_img, img_backgroud)
#cv2.imshow("img", img_backgroud)
#cv2.waitKey(0)
if __name__ == '__main__':
#getInfo(r"test.mp4")
#getFrames(r"test.mp4", [10, 20])
video = r"test.mp4"
img = "test.jpg"
mp4toJpg(video, img)