A boot animation is the first thing a user sees after turning on a phone or tablet. This introductory part of the ROM is very important, and directly influences our experience of said ROM. For this, Android uses PNG files and a desc.txt bundled into one zip. The text file contains resolution and frame rate information so that the boot animation displays at the correct size and with the desired speed.
Making a public preview of boot animation wasn’t as easy as it sounds. Recording from a device with a video camera definitely doesn’t look professional, and the video quality leaves much to be desired. If you ever planned to make a video of your boot animation, you should definitely give a try to a Windows-only tool written by XDA Forum Member makers_mark. A batch script pulls down the boot animation from the device using ADB. Then, it converts the bootanimation into an MP4 file that is ready to be uploaded to YouTube or similar video delivery services. The script uses such tools like 7zip to unpack the archive and FFmpeg to convert those files into a video. The process is carefully described in the thread, with an explanation of the particular elements that go into boot animations.
The tool works only on Windows machines, and it can be downloaded from the original thread._________