ffmpeg version 3.2.10-1~deb9u1~bpo8+1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 4.9.2 (Debian 4.9.2-10)

/usr/bin/ffmpeg -y
   -i "INPUT.MP4"
   -i "WM.PNG"
   -filter_complex "
    [1:v]format=rgba,colorchannelmixer=aa=0.4[fg];
[fg]setsar=1[logo];
[0][logo]overlay=10:10"
"OUTPUT.MP4"

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input-2min.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
  Duration: 00:02:06.17, start: 0.000000, bitrate: 2677 kb/s

    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 2494 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      handler_name    : VideoHandler

    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 175 kb/s (default)
    Metadata:
          handler_name    : Stereo