[FFmpeg-devel] overlay filter option/alternative

Ryan Williams ryan at ryanwilliams.id.au
Fri Dec 4 06:29:28 CET 2015

EDIT: Fixed errors in syntax.

TLDR, Would you consider an 'underlay' filter or perhaps an option on the 'overlay' filter that reverses the order of the input labels?

Consider the following shorthand syntax "[input][a] overlay, [b] overlay, [c] overlay [output]"
Which expands to "[input][a] overlay [unnamed1]; [b][unnamed1] overlay [unnamed2]; [c][unnamed2] overlay [output]"
Giving the final layer composition of "c,b,input,a"

If there was an underlay filter or equivalent the shorthand syntax "[input][a] overlay, [b] underlay, [c] underlay [output]"
Would expand to "[input][a] overlay [unnamed1]; [b][unnamed1] underlay [unnamed2]; [c][unnamed2] underlay [output]"
Giving the final layer composition of "input,a,b,c"

I am aware that I can provide longhand syntax to achieve the same result but I am programmatically apply a varying number of watermarks and would like to avoid a lot of temporary labels.
If you're open to the idea I'm willing to code it.

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