Python 视频转场特效处理笔记

本文参考Python-OpenCV 实现美图秀秀视频剪辑效果【特效】_opencv 多张图片视频特效-CSDN博客

最近研究了点python处理视频相关的东西，本文展示特效包括，竖向开幕/横向开幕，渐隐/渐显，推近/拉远，方形开幕，灰度渐变。不多说，直接上代码。

import cv2
import numpy as np
import random

def addCardFrame(video_writer,img,backimg=None,fps=18,sec=1,eachtime=0.5):
    """视频特效:卡帧"""
    rows, cols = img.shape[:2]

    '''缩放原图80%'''
    img = cv2.resize(img, (int(cols * 0.8),int(rows * 0.8)))
    rows_new, cols_new = img.shape[:2]

    '''准备更大的画布'''
    cav = None
    if backimg is None:
        cav_np = np.zeros((rows, cols), np.uint8)
        cav = cv2.cvtColor(cav_np, cv2.COLOR_GRAY2BGR)
    else:
        cav = backimg

    '''偏移量准备'''
    dic = {
        0: (int(cols * 0.08), int(rows * 0.12)),
        1: (int(cols * 0.10), int(rows * 0.10)),
        2: (int(cols * 0.12), int(rows * 0.08)),
        3: (int(cols * 0.12), int(rows * 0.07)),
        4: (int(cols * 0.12), int(rows * 0.06)),
        5: (int(cols * 0.14), int(rows * 0.07)),
        6: (int(cols * 0.16), int(rows * 0.07)),
        7: (int(cols * 0.15), int(rows * 0.09)),
        8: (int(cols * 0.14), int(rows * 0.10)),
        9: (int(cols * 0.14), int(rows * 0.07)),
        10: (int(cols * 0.13), int(rows * 0.05)),
        11: (int(cols * 0.14), int(rows * 0.06)),
        12: (int(cols * 0.14), int(rows * 0.08)),
        13: (int(cols * 0.15), int(rows * 0.10)),
        14: (int(cols * 0.14), int(rows * 0.09)),
        15: (int(cols * 0.12), int(rows * 0.12)),
        16: (int(cols * 0.10), int(rows * 0.10)),
        17: (int(cols * 0.08), int(rows * 0.12))
    }

    '''添加特效展示'''
    for _ in range(int(sec)):
        xs, ys = dic[random.randrange(0,18,1)]
        xe, ye = (xs + rows_new, ys + cols_new)
        cav[xs: xe, ys: ye] = img
        for _ in range(int(eachtime*fps)):
            video_writer.write(cav)

def addVerticalOpening(video_writer,img,backimg=None,fps=18,sec=1,mode='H'):
    """视频特效:竖向开幕H 横向开幕V"""
    rows, cols = img.shape[:2]

    '''画布准备'''
    cav = None
    if backimg is None:
        cav_np = np.zeros((rows, cols), np.uint8)
        cav = cv2.cvtColor(cav_np, cv2.COLOR_GRAY2BGR)
    else:
        cav = backimg

    '''特效展示'''
    load_f = 1000/fps
    n = 5
    height_half,weight_half = int(rows / 2),int(cols / 2)
    xs1, xs2 = height_half, height_half
    xe1, xe2 = height_half, height_half
    ys1, ys2 = weight_half, weight_half
    ye1, ye2 = weight_half, weight_half
    for t in range(int(sec*1000 // load_f)):
        load_percent = 0.5 / (sec ** n) * ((sec - t * load_f / 1000) ** n)
        if mode=='H':
            load_height = int((0.5 - load_percent) * rows)
            xe1, xe2 = height_half - load_height, height_half + load_height
            cav[xe1:xs1, :] = img[xe1:xs1, :]
            cav[xs2:xe2, :] = img[xs2:xe2, :]
            xs1, xs2 = xe1, xe2
        else:
            load_weight = int((0.5 - load_percent) * cols)
            ye1, ye2 = weight_half - load_weight,weight_half + load_weight
            cav[:, ye1:ys1] = img[:, ye1:ys1]
            cav[:, ys2:ye2] = img[:, ys2:ye2]
            ys1, ys2 = ye1, ye2
        video_writer.write(cav)

def addFadeOut(video_writer,img,backimg=None,fps=18,sec=2):
    """视频特效:渐隐"""

    '''特效展示'''
    load_f = 1000/fps
    n = 1
    for t in range(int(sec * 1000 // load_f)):
        sc = 1 - 1 / (sec ** n) * (t * load_f / 1000) ** n
        img_show = cv2.multiply(img, (1, 1, 1, 1), scale=sc)
        video_writer.write(img_show)

def addFadeIn(video_writer,img,fps=18,sec=2):
    """视频特效:渐隐"""

    '''特效展示'''
    load_f = 1000/fps
    n = 1.5
    for t in range(int(sec * 1000 // load_f)):
        sc = 1 - 1 / (sec ** n) * (t * load_f / 1000) ** n
        sc = 1 - 1 / (sec ** n) * (sec - t * load_f / 1000) ** n
        img_show = cv2.multiply(img, (1, 1, 1, 1), scale=sc)
        video_writer.write(img_show)

def percent_func_gen(a, b, time, n, mode):
    """
    高次多项式计算函数生成器
    :param a: 起始百分比（如：0.25）
    :param b: 结束百分比
    :param time: 动画持续时间
    :param n: 多项式次数
    :param mode: faster（越来越快）、slower（越来越慢）
    :return: 每个时刻到达百分比的计算函数
    """
    if mode == "slower":
        a, b = b, a
    delta = abs(a - b)
    sgn = 1 if b - a > 0 else (-1 if b - a < 0 else 0)
    def percent_calc(ti):
        if mode == "slower":
            ti = time - ti
        return sgn * delta / (time ** n) * (ti ** n) + a
    return percent_calc
    
def addAdvance(video_writer,img,fps=18,sec=2):
    """视频特效:推近"""
    rows, cols = img.shape[:2]

    '''特效展示'''
    load_f = 1000/fps
    percent_func = percent_func_gen(a=0, b=0.2, time=sec, n=4, mode="slower")
    for t in range(int(sec * 1000 // load_f + 1)):
        percent = percent_func(t * load_f / 1000)
        xs, xe = int(percent * rows), int((1 - percent) * rows)
        ys, ye = int(percent * cols), int((1 - percent) * cols)
        img_show = img[xs:xe, ys:ye]
        img_show = cv2.resize(img_show, (cols,rows))
        video_writer.write(img_show)

def addZoomOut(video_writer,img,fps=18,sec=2):
    """视频特效:拉远"""
    rows, cols = img.shape[:2]

    '''特效展示'''
    load_f = 1000/fps
    percent_func = percent_func_gen(a=0.2, b=0, time=sec, n=3, mode="slower")
    for t in range(int(sec * 1000 // load_f + 1)):
        percent = percent_func(t * load_f / 1000)
        xs, xe = int(percent * rows), int((1 - percent) * rows)
        ys, ye = int(percent * cols), int((1 - percent) * cols)
        img_show = img[xs:xe, ys:ye]
        img_show = cv2.resize(img_show, (cols,rows))
        video_writer.write(img_show)

def addSquareOpening(video_writer,img,backimg=None,fps=18,sec=2):
    """视频特效:方形开幕"""
    rows, cols = img.shape[:2]
    '''画布准备'''
    cav = None
    if backimg is None:
        cav_np = np.zeros((rows, cols), np.uint8)
        cav = cv2.cvtColor(cav_np, cv2.COLOR_GRAY2BGR)
    else:
        cav = backimg
        
    '''特效展示'''
    load_f = 1000/fps
    percent_func = percent_func_gen(a=0, b=0.5, time=sec, n=5, mode="faster")
    rows_half = rows // 2
    cols_half = cols // 2
    for t in range(int(sec * 1000 // load_f + 1)):
        percent = percent_func(t * load_f / 1000)
        width, height = int(percent * rows), int(percent * cols)
        xs, xe = rows_half-width, rows_half+width
        ys, ye = cols_half-height, cols_half+height
        cav[xs:xe, ys:ye] = img[xs:xe, ys:ye]
        video_writer.write(cav)
        
def addGradientWipe(video_writer,img,backimg=None,fps=18,sec=2,mode='L'):   
    """视频特效:灰度渐变 L左 R右 U上 D下"""
    rows, cols = img.shape[:2]

    '''灰度准备'''
    img_gray_bgr = None
    if backimg is None:
        img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        img_gray_bgr = cv2.cvtColor(img_gray, cv2.COLOR_GRAY2BGR)
    else:
        img_gray_bgr = backimg

    '''特效展示'''
    load_f = 1000/fps
    percent_func = percent_func_gen(a=0, b=1, time=sec, n=1, mode="slower")
    if mode=='L':
        ys, ye = 0, 0
        for t in range(int(sec * 1000 // load_f + 1)):
            percent = percent_func(t * load_f / 1000)
            width = int(percent * cols)
            ye = width
            img_gray_bgr[:, ys:ye] = img[:, ys:ye] 
            ys = ye
            video_writer.write(img_gray_bgr)
    if mode=='R':
        ys, ye = cols, cols
        for t in range(int(sec * 1000 // load_f + 1)):
            percent = percent_func(t * load_f / 1000)
            width = int(percent * cols)
            ys = cols-width
            img_gray_bgr[:, ys:ye] = img[:, ys:ye] 
            ye = ys
            video_writer.write(img_gray_bgr)
    if mode=='U':
        xs, xe = 0, 0
        for t in range(int(sec * 1000 // load_f + 1)):
            percent = percent_func(t * load_f / 1000)
            height = int(percent * rows)
            xe = height
            img_gray_bgr[xs:xe, :] = img[xs:xe, :] 
            xs = xe
            video_writer.write(img_gray_bgr)
    if mode=='D':
        xs, xe = rows, rows
        for t in range(int(sec * 1000 // load_f + 1)):
            percent = percent_func(t * load_f / 1000)
            height = int(percent * rows)
            xs = cols-height
            img_gray_bgr[xs:xe, :] = img[xs:xe, :] 
            xe = xs
            video_writer.write(img_gray_bgr)

调用方法进行视频合成

fps = 25 #视频帧数
sec = 3 # 特效时间
eachtime = 0.5 # 每帧所占时间
video_temp_path= "test.mp4"
img1 = cv2.imread("0.jpg")
img2 = cv2.imread("1.jpg")
img3 = cv2.imread("2.jpg")
video_height,video_weight =img.shape[:2]
video_writer = cv2.VideoWriter(video_temp_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (video_weight,video_height))
addCardFrame(video_writer,img1,fps,sec,eachtime)
addVerticalOpening(video_writer,img2,img1,fps,sec,mode='V')
addFadeOut(video_writer,img3,fps,sec)
addFadeIn(video_writer,img1,fps,sec)
addAdvance(video_writer,img2,fps,sec)
addZoomOut(video_writer,img3,fps,sec)
addSquareOpening(video_writer,img2,img3,fps,sec)
addGradientWipe(video_writer,img1,img2,fps,sec,mode='D')
video_writer.release()

视频效果如下：