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Video Technology 101

January 20, 2025 · 21 min read · Page View:
Tutorial
Video | Resolution | Frame Rate | Bit Rate | Codec | Color Depth | HDR | Video Format

Do you really understand the video technology? What is the frame rate, resolution, bit rate and their relationships? Do you know the parameters p and K in the terminology 1080p and 4K? Do you know how to describe the video quality? What is the Blu-ray Disc on earth? What the difference between the codec such as H.264/AVC, H.265/HEVC, AV1? You may notice the Apple ProRes in apple, so do you really understand what it for? Do you know the HDR and Dolby Vision? So why there are so many tailers such as .mp4, .mkv, .flv, etc?

Now this Video Technology 101 will introduce them to you.

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About the Systemd

January 18, 2025 · 2 min read · Page View:
Tutorial
Systemd

It has been a long time since the linux used init to manage the startup process, such as sudo /etc/init.d/apache2 start or service apache2 start, but the init is serial. To address this issue, the systemd was born. The d is the abbreviation of daemon, which means the systemd is a daemon manager. The systemd substitutes the initd and becomes the default main process PID 1.

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The Tips About Dockerfile

January 18, 2025 · 3 min read · Page View:
Tutorial
Docker

Normally, we often write a Dockerfile in the current directory.

  • The Dockerfile is a configuration file that describes how to build the image. You can refer to the official documentation[1] for more details.
  • If you list more than one CMD, only the last one takes effect. So if you have multiple commands to run, you better write them in a script file.
  • Docker is not the VMware, there is no systemd in the container. Its startup program is the container application process. The container exists for the main process. Once the main process exits, the container loses its meaning of existence and thus exits. So when you execute multiple commands and if they are blocking, you better write the previous commands in nohup and the last command in the blocking command. (never use the command such as CMD service nginx start, the CMD only will execute as CMD [ "sh", "-c", "service nginx start"], when the sh is executed, the container will exit, the correct way is run it directly CMD ["nginx", "-g", "daemon off;"])
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Docker 101

January 16, 2025 · 8 min read · Page View:
Tutorial
Docker | Systemd

Docker is a practical tool for everyday use, and like Git, you can learn it in just 30 minutes.

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The Overview of Security

January 8, 2025 · 6 min read · Page View:
Tutorial
Security | Hash | Encryption | Signature

In today’s digital age, security is paramount. As we increasingly rely on technology for communication, commerce, and data storage, understanding the fundamentals of security becomes essential. This article provides an overview of key security concepts, including encryption, digest algorithms, and digital signatures. By exploring these topics, we aim to equip you with the knowledge to protect your digital assets and ensure the integrity and confidentiality of your information. Whether you’re a tech enthusiast or a professional in the field, this guide will offer valuable insights into the mechanisms that safeguard our digital world.

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