timerring

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.

Read the full text -> A total of 4.34k words


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.

Read the full text -> A total of 0.49k words


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 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;"])
Read the full text -> A total of 0.77k words