Question

Im trying to scale a video so that it is always 512 wide where the height changes in proportion to the original video.
Once scaled, I then want to apply a watermark/overlay to the video, therefore the video will scale but the watermark wont.

I am able to achieve each of these separately using the following filters:

Scale

-vf "scale=512:-1"

Watermark

-vf "movie=watermark.png [watermark]; [in][watermark] overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]"

They work successfully on their own.

However when trying to combine the two, Im having a bit of trouble.

Having both as parameters of course does not work as one will override the other.

Ive tried:

-vf "scale=512:-1,movie=watermark.png [watermark]; [in][watermark] overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]"

my thinking was that the scale would be applied first then the watermark but all I get is an error

Too many inputs specified for the "movie" filter.

Error opening filters!

Then changing the , to a ; resulted in:

Simple filtergraph ‘scale=512:-1;
movie=watermark.png
[watermark]; [in][watermark]
overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]’ does not have
exactly one input and output.

Error opening filters!

I presume I need to do something more with filterchains but Im struggling to figure it out.

Any ideas anyone?

Many thanks in advance.

Answer 1

Thank you to both @DiJuMx and @LordNeckbeard, you both got me closer to my solution. Ive not tried the filter_complex option yet but it certainly looks simpler.

The solution I found to work is:

-vf "movie=watermark.png [watermark]; [in]scale=512:trunc(ow/a/2)*2 [scale]; [scale][watermark] overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]"

Note that Ive replaced the -1 in the scale as that had the potential to cause an uneven number of pixels in the height of the video when scaling which would then cause encoding errors.