264-mary.mp4 — Direct

Разница между MPEG-4, AVC/H.264 и MP4 - Elecard

You are most likely encountering this file in one of the following scenarios:

This almost certainly refers to H.264 (also known as AVC), the most common video compression standard in the world. It is used for everything from YouTube videos to Blu-ray discs because it balances high quality with small file sizes.

If you are using software like x264 to convert files, the output might be named after the codec used during the process.