I had videos in H.264 codec that I wanted to reencode to H.265. The reason is that H.265 (a.k.a. High Efficiency Video Codec, HEVC) is a more modern and efficient format than H.264 (a.k.a. Advanced Video Codec, AVC), which allows to keep the same quality with about twice less storage.

As I make from time to time YouTube, Instagram, and TikTok videos, which I need to backup, it is always good to store your data in the most storage-efficient format.

Often, when running a program in console, one needs to save all its output to a file. Very often, such a program writes both to the standard output (stdout) and to the standard error output (stderr). For example, by default, in a Python program the print function writes to stdout and the functions of the logging module to stderr. Therefore, one needs to redirect both stdout and stderr to the same file.