python - 为什么我的python脚本输出文件为空

Question

我正在创建一个 python 脚本来记录桌面屏幕。

在这个我只取用户选择的区域，只记录选择的区域并将其转换为视频文件。

但是在执行此操作时，脚本的输出是一个空的视频文件(0 字节)

谁能告诉我我在哪里做错了。因为它在没有 bbox(x1,x2,y1,y2) 的情况下工作正常.

这是代码:
编辑:

import tkinter as tk
from tkinter import *
from tkinter import ttk ,FLAT
from PIL import Image, ImageTk, ImageGrab, ImageEnhance
import cv2
import numpy as np
import threading
filename="test.avi"
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
frame_rate = 10
root = tk.Tk()


def show_image(image):
    win = tk.Toplevel()
    win.image = ImageTk.PhotoImage(image)
    tk.Label(win, image=win.image).pack()
    win.grab_set()
    win.wait_window(win)

def area_sel():
    x1 = y1 = x2 = y2 = 0
    roi_image = None

    def on_mouse_down(event):
        nonlocal x1, y1
        x1, y1 = event.x, event.y
        canvas.create_rectangle(x1, y1, x1, y1, outline='red', tag='roi')

    def on_mouse_move(event):
        nonlocal roi_image, x2, y2
        x2, y2 = event.x, event.y
        canvas.delete('roi-image') 
        roi_image = image.crop((x1, y1, x2, y2)) 
        canvas.image = ImageTk.PhotoImage(roi_image)
        canvas.create_image(x1, y1, image=canvas.image, tag=('roi-image'), anchor='nw')
        canvas.coords('roi', x1, y1, x2, y2)
        canvas.lift('roi') 

    root.withdraw()  
    image = ImageGrab.grab()  
    bgimage = ImageEnhance.Brightness(image).enhance(0.3)  
    win = tk.Toplevel()
    win.attributes('-fullscreen', 1)
    win.attributes('-topmost', 1)
    canvas = tk.Canvas(win, highlightthickness=0)
    canvas.pack(fill='both', expand=1)
    tkimage = ImageTk.PhotoImage(bgimage)
    canvas.create_image(0, 0, image=tkimage, anchor='nw', tag='images')
    win.bind('<ButtonPress-1>', on_mouse_down)
    win.bind('<B1-Motion>', on_mouse_move)
    win.bind('<ButtonRelease-1>', lambda e: win.destroy())
    win.focus_force()
    win.grab_set()
    win.wait_window(win)
    root.deiconify()  

    if roi_image:
        region = x1, y1, x2, y2

        start_recording(region) #calling main function to record screen
        return region


def recording_screen(x1, y1, x2, y2):
    global recording
    recording = True

    while recording:

        img = ImageGrab.grab(bbox=(x1, y1, x2, y2))
        frame=np.array(img) # for recording
        out.write(cv2.cvtColor(frame,cv2.COLOR_RGB2BGR))

out = cv2.VideoWriter() 
def start_recording(region):
    x1,y1,x2,y2 = region
    if not out.isOpened():

            out.open(filename,fourcc, frame_rate,(x2-x1,y2-y1))
    threading.Thread(target=recording_screen, args=region, daemon=True).start()

def stop_recording():
    global recording
    recording = False
    out.release()

sel_area = ttk.Button(root, text='select area to Record', width=30, command=area_sel)
sel_area.grid(row=0, column=0)

stp_rec = ttk.Button(root, text='Stop Recording', width=30, command=stop_recording)
stp_rec.grid(row=0, column=1)

root.mainloop()

Answer 1

您正在使用 ImageGrab仅适用于 macOS 和 Windows，因此我无法在我的设置中测试您的完整代码。

您的代码中的问题是您已将区域选择和视频录制结合起来。选择区域后，您将拥有 x1 , y1 , x2 , 和 y2 .返回这些值。初始化cv2.VideoWriter第一次。

您现在可以尝试的是使用传递给 start_recording((x1, y1, x2, y2)) 的参数。 .

def start_recording(region):
    x1,y1,x2,y2 = region
    if not out.isOpened():

        out.open(filename,fourcc, frame_rate,(y2-y1,x2-x1)) #given x2 > x1, y2 > y1
    threading.Thread(target=recording_screen, args=region, daemon=True).start()

编辑:

问题是在以下调用中传递了错误的形状。

out.open(filename,fourcc, frame_rate,(y2-y1,x2-x1))

Size传递的值为 (y2-y1,x2-x1)即 (height, width) .但是，构造函数需要 (width, height) .见文档 here .

此外， img = ImageGrab.grab(bbox=(x1, y1, x2, y2))返回 RGB image .但是 out.write(frame)预计 BGR image .它可以固定为:

img = ImageGrab.grab(bbox=(x1, y1, x2, y2))
frame = np.array(img)
out.write(cv2.cvtColor(frame, cv2.COLOR_RGB2BGR))