I currently have this string to add watermark.png to test.mp4. It makes the watermark go from the top center of the video, to the bottom every 5 seconds then loops back to the top.

I want it to continue to do this, but to only be 50% opacity.

ffmpeg -i test.mp4 -loop 1 -i watermark.png -filter_complex "overlay=x=(main_w-overlay_w)/2:y='if(gte(t,0), ((H+h)\/5)\*mod(t\,5)-h, NAN)':shortest=1" output.mp4

I also have this string that I found, but am not sure how to combine it to mine.

ffmpeg -i input.mp4 -i watermark.jpg -filter_complex "[1]format=rgba,colorchannelmixer=aa=0.5[logo];[0][logo]overlay=(W-w)/2:(H-h)/2:format=auto,format=yuv420p" -c:a copy output.mp4

If someone could help me with a better string I'd appreciate it.