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ffmpeg -i input.mp4 -vf "delogo=x=10:y=20:w=150:h=50" -c:a copy output.mp4 x: 水印左上角的水平位置（以像素为单位）. y: 水印左上角的垂直位置（以像素为单位）. w: 水印框的宽度. h: 水印框的高度. -c: 直接复制原始音频，无需重新编码，从而节省时间.

#pragma once 作用： 1. 当一个头文件被多个源文件或其他头文件直接或间接 #include 时，该指令能确保它只被编译一次。 2. 避免宏名冲突：传统的 #ifndef 保护需要为每个文件设计独特的宏名（如 __MY_HEADER_H__）， 若不小心在不同文件用了相同的宏名会导致代码失效；而 #pragma once 基于物理文件路径，彻底避免了命名污染和冲突。 3. 书写简洁：只需在头文件最上方写一行即可，无需写 #ifndef、#define 和 #endif 4 与#ifndef的区别： 4.1 标准性：#ifndef 是 C++ 标准支持的传统方法（也称 Include Guard）； 而 #pragma once 虽然是非标准指令，但现代绝大多数主流编译器（如 GCC、Clang、MSVC）都提供了完美支持。 4.2 控制粒度：#ifndef 可以防范同一文件内局部的 代码片段 重复，而 #pragma once 只能针对 整个物理文件 。

  Comparison of Modern C++ Approaches Implementation Type Mechanism Resolution Time Memory Overhead Use Case Runtime (Functional) std::function & Lambdas Runtime Small heap allocation (if lambda captures exceed small-buffer optimization) When algorithms must change on the fly during program execution. Compile-time (Static) Templates & Concepts ( requires ) Compile-time Zero runtime overhead (inlines perfectly) High-performance systems where strategies are known at compile time. Example 1: #include <bits/stdc++.h> class SortingStrategy { public: virtual void sort(std::vector<int>& arr) = 0; }; class BubbleSort : public SortingStrategy { public: void sort(std::vector<int>& arr) override { // Implement Bubble Sort algorithm } }; class QuickSort : public SortingStrategy { public: void sort(std::vector<int>& arr) override { // Implement Quick Sort algorithm } }; // Add more sorting algorithms as ne...

The Flyweight design pattern is a structural pattern designed to minimize memory usage by sharing as much data as possible with other similar objects. It divides an object's data into two categories: intrinsic state(heavy, constant, and shareable data) and extrinsic state (lightweight, unique, context-specific data) #include <iostream> #include <string> #include <string_view> #include <unordered_map> #include <vector> #include <memory> #include <shared_mutex> // 1. INTRINSIC STATE (The Flyweight) // This class contains heavy, immutable data shared across thousands of instances. class TreeModel { public: TreeModel(std::string name, std::string color, std::vector texture_data) : name_(std::move(name)), color_(std::move(color)), texture_bytes_(std::move(texture_data)) { std::cout texture_bytes_; // Simulates heavy mesh/texture data }; // 2. FLYWEIGHT FACTORY // Manages the shared pool of flyweights. It ensures obje...

Creational: Factory Method (class) Abstract Factory (object) Builder  (object) Prototype  (object) Singleton  (object) Structral: Adapter (class/object) Bridge (object) Composite (object) Decorator  (object) Facade  (object) Flyweight   (object) Proxy  (object) Behavioral: Interpreter (class) Template Method (class) Chain of Responsibility (object) Command (object) Iterator (object) Mediator (object) Memento (object) Observer (object) State (object) Strategy (object) Visitor (object)

Code: ffmpeg -i i1.jpg -vf "drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=168:fontcolor=white@0.5:x=(w-text_w)/2:y=(h-text_h)/2" output.jpg Multi Line Version: ffmpeg -i i1.jpg -vf "drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x=w*0.1:y=h*0.2,drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x=w*0.4:y=h*0.2,drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x=w*0.7:y=h*0.2,drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x=w*0.1:y=h*0.5,drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x=w*0.4:y=h*0.5,drawtext=text='仅为开户使用':fontfile='C\:/Windows/Fonts/msyh.ttc':fontsize=w*0.03:fontcolor=white@0.7:x...

Tree structure of the project. The code of main.cc. #include <iostream> #include "spdlog/spdlog.h" #include "spdlog/sinks/basic_file_sink.h" #include "spdlog/sinks/rotating_file_sink.h" void do_work_in_another_file(); void rotating_example() { try { // Create a file rotating logger with 5 MB size max and 3 rotated files auto max_size = 1048576 * 5; auto max_files = 3; // Set output time pattern // %f: Time accurate to microseconds // %n: Output mode "some_logger_name" // %l: Prints the severity level of the log message. Example include info, warn, error, debug or critical. // %v: Prints the actual text or payload of the log message that you passed to the function. spdlog::set_pattern("[%Y-%m-%d %H:%M:%S.%f] [%n] [%l] %v"); // Set it as default so you can spdlog::info() directly. auto logger = spdlog::rotating_logger_mt("som...

" 显示行号 set number " 将Tab键自动转换为空格 set expandtab " 设置Tab键本身的宽度为4个空格 set tabstop=4 " 设置按退格键(BackSpace)时一次删除4个空格 set softtabstop=4 " 设置使用>或<进行缩进时的宽度为4个空格 set shiftwidth=4 " 开启自动缩进(新行继承上一行的缩进) set autoindent " 开启C/C++语言智能缩进 set cindent " 搜索优化 set incsearch set ignorecase " 语法高亮 syntax on " 开启256色支持(在终端使用时非常重要) set t_Co=256

1. Installing vim Open msys2 ucrt64 terminal and enter command as follows: ``` pacman -S vim ``` 2. Configure vim Open msys2 ucrt64 terminal and enter command as follows: ``` cd ~ touch .vimrc ``` Adding the content into .vimrc which you want to. For example: ``` set number ```

1. Installing CMake CMake Download 2. Building Source Code Files hello.cc #include <iostream> #include "spdlog/spdlog.h" int main(void) { spdlog::info("Welcome to spdlog!"); std::cout << "Hello World!" << std::endl; return 0; } 3. Building CMakeLists.txt File # 指定CMake最低版本 cmake_minimum_required(VERSION 3.10) # 必须在项目名称前指定C++编译器 set (CMAKE_CXX_COMPILER "g++.exe") # 指定项目名称和使用的编程语言 project(MyProject LANGUAGES CXX) # 添加spdlog目录,让spdlog可用 add_subdirectory(third_party/spdlog) # 指定C++标准 set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED True) # 指定生成的可执行文件及对应的源文件 add_executable(my_app main.cc) # 使用spdlog头文件模式 target_link_libraries(my_app PRIVATE spdlog::spdlog_header_only) 4. Building Project # 1. 配置项目（生成 Makefile 或 Ninja 文件） # -G "MinGW Makefiles" 指定使用MinGW而不是Windows默认的nmake, # 当然要提前安装MinGW到C:/MinGW安装路径不要有空格否则可能报错 # 且C:/MinGW/bin要放到Windows的环境路径上 # -G Ninja 指定使用Ninja，同样Ninja也需要提前准备好 #...

FFmpeg extract audio mp3 from mp4 video ffmpeg -i video.mp4 -b:a 192K -vn music.mp3 How to merge audio and video file in ffmpeg ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac output.mp4

Install ctags # pkg install ctags Execute ctags Go to the directory where you want to generate ctags file and run command as follows: $ /usr/local/bin/exctags -R

The command is as follows: :) ALTER TABLE tablename UPDATE column_name = column expresion1 WHERE  expression; Example: :) ALTER TABLE tablename UPDATE time = time / 100 WHERE id = 0;

Open .py file with vim I got error message as following: " YCM error. The ycmd server SHUT DOWN (restart wit...the instructions in the documentation) " Solution: 1. Install cmake # pkg install cmake 2. Compile $ cd /home/j/.vim/bundle/YouCompleteMe $ python3 install.py

Install # pkg install v2ray Configuration Set v2ray system startup. Add content as following below to /etc/rc.conf # sysrc v2ray_enable=yes set v2ray's config.json of client. {   "log": {     "access": "",     "error": "",     "loglevel": "warning"   },   "inbounds": [     {       "tag": "socks",       "port": 10808, // port of client for socks       "listen": "127.0.0.1",       "protocol": "socks",       "sniffing": {         "enabled": true,         "destOverride": [           "http",           "tls"         ],         "routeOnly": false       },       "settings": {         "auth": "noauth",         "udp": true,         "allowTransparen...

 Solution: $ mkdir ~/.vim/autoload $ cp ~/.vim/bundle/vim-colors-solarized/autoload/togglebg.vim ~/.vim/autoload

Solution: $ mkdir ~/.vim/colors $ cp ~/.vim/bundle/Zenburn/colors/zenburn.vim ~/.vim/colors/   

Install VIM # pkg install vim VIM Extensions The first thing you need is a good extension manager. Vundle VIM has serveral extension managers, but I strongly recommend Vundle . Let's get Vundle installed: $ git clone https://github.com/gmarik/Vundle.vim.git ~/.vim/bundle/Vundle.vim This command downloads the Vundle plugin manager and chucks it in your VIM bundles directory. Now you  can manage all your extensions from the .vimrc configuration file . $ touch ~/.vimrc Now set up Vundle in your .vimrc by adding the following to the top of the file: set nocompatible              " required filetype off                  " required " set the runtime path to include Vundle and initialize set rtp+=~/.vim/bundle/Vundle.vim call vundle#begin() " alternatively, pass a path where Vundle should install plugins "call vundle#begin('~/some/path/here') " let Vundle manage Vundle, required Plugin 'gmarik/Vundle.vim' " ...

When I use clang to compile test.c, the following error occurs. fatal error : 'curl/curl.h' file not found The compile command is: $ clang test.c -o test I did some research. Then I know I need to change the compile command as follows: $ clang -I/usr/local/include -L/usr/local/lib -lcurl test.c -o test

1. fopen is defined in the C standard library , but open is not. Therefore fopen is more portable than open. 2. fopen provides you with buffering IO that may turn out to be a lot faster than what you're doing with open.