ffmpeg - Make a white line look thicker

Question

I've been actively playing around with ffmpeg for the past few days, and now I want to make an audio visualiser, just with the showwaves filter (I made it white using p2p mode, and I don't want to use a mode that would just fill the wave with white).

The problem with the showwaves filter is that it creates a very thin 1px line which makes it pretty hard to see when it varies really fast. At a low video bitrate it becomes almost invisible.

So I tried several ways to make this thin white line look thicker, including geq to increase alpha values, gblur+increasing contrast. For now I got the most "satisfying" results by making the size of the showwaves 10x smaller and then using scale to make it the size I want. But the result is very pixelated so that's not really suitable. I've also thought of duplicating the wave a lot and displacing the copies around but I don't think it would be very performance-friendly.

So I was wondering whether there is anyway of adding some outline/glow/shadow/anything that would make this line look a bit thicker (like 5px would be enough), or anything else than showwaves that would somehow achieve what I'm looking for.

Thanks

Answer 1

Use one or more dilation filters after showwaves filter.

Answer 2

An example of adding dilation might look like:

ffmpeg -i example_in.mp3 -filter_complex \
"[0:a]showwaves=mode=p2p:s=1280x480:colors=Magenta|Azure|White:r=25; \
 [v]dilation=threshold3=10[v]" \
-map "[v]" -map 0:a -pix_fmt yuv420p \
-b:a 360k -r:a 44100  example_out.mp4