Add flv.hexpat

[zn123]

https://veovera.org/docs/enhanced/enhanced-rtmp-v2#flv-file-format-overview

[zn123]

ffmpeg -i test.mp4 -vcodec copy -acodec copy test.flv

[zn123]

test.zip

[paxcut]

Have you tested the magic for auto detection of pattern file? You may want to set it so that you only have to place one variable at the end instead of two. That would make importing from it simpler.

[zn123]

你测试过自动检测模式文件的魔法吗？ 你可能需要设置一下，这样只需要在末尾放置一个变量，而不是两个。这样导入会更简单。

Consider the compatibility of different versions

[zn123]

@reviewer ：Could you please help expedite the review process for this PR when you have a moment? Thank you!

[WerWolv]

Please upload the test file to the folder mentioned in the PR template and add your pattern to the table in the readme. After that it should be good to merge 👍

[zn123]

请将测试文件上传到 PR 模板中提到的文件夹，并将你的模式添加到 readme 文件中的表格中。之后就可以合并了👍

already submitted