[FFmpeg-user] 'overlay' filter question

[Moritz Barsnick]

On Mon, Apr 06, 2020 at 06:39:16 -0400, Mark Filipak wrote:
> ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
>                                                   ^
> What is ..................................... this?
> It's not documented.

In the filters syntax, if you don't name the option, the order of
values implies their meaning.

In other words:
    filtername=option1=1:option2=42:option3=yes

can be replaced with
    filtername=1:42:yes
if and only if these are the first three documented options.

(On the other hand, you can always change the order of options, if you
name them properly:
    filtername=option27=something:option2=42:option3=yes:option1=1
)

I don't recommend to use shorthand, except in cases where it's really clear.
For example, I use
    fps=25
instead of
    fps=fps=25
because it's faster to write and I know what I'm doing.

For the overlay filter, the first two options are x and y.
So what you see could be written as:
    overlay=x=10:y=main_h-overlay_h-10

Cheers,
Moritz