"ffmpeg -i test.mp4 -vf drawtext=fontfile=arial.ttf:text=welcome output.mp4 " ,what means about "-vf"?

Question

I want to add text to video, and useffmpeg -i test.mp4 -vf drawtext=fontfile=arial.ttf:text=welcome output.mp4 ,it worked,but I want to know detail reason. What means about "-i"?what means about "-vf"? please help me! I have found ffmpeg android document.But I do not find editable area to input cmd to search detail explain。where is it?

Answer 1

what means about “-i” , means “input”?

Yes.

what means about “-vf”?

Video Filter.

where can I find FFmpeg explain?

https://ffmpeg.org/ffmpeg.html. People don't think android special unless you point it out.

I do not find editable area to input cmd to search

Use browser Ctrl-F to search in webpage first. If not working, try using search engines.

I find "delogo" can not exe ,when x=0 or y=0,can you help me?

Google search the web first. If no use, open another question and explain your issue in detail (for example, what command you used, and what kind of "cannot exe"?).