ubuntu@ip-172-30-0-218:~/hw-ffmpeg$ ffmpeg -y -i result.png -hwaccel cuvid -c:v vp8_cuvid -i test.webm -c:v h264_nvenc -b:v 10M -pix_fmt yuv420p -r 30 -an -filter_complex "[0:v][1:v]overlay=eval='init'[merge];[merge]lut3d=lut.cube" testResult.mp4
ffmpeg version N-87144-g1a0d9b5 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  configuration: --prefix=/home/ubuntu/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/ubuntu/ffmpeg_build/include --extra-ldflags=-L/home/ubuntu/ffmpeg_build/lib --bindir=/home/ubuntu/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libx264 --enable-nonfree --enable-libvpx --enable-nvenc --enable-cuda
  libavutil      55. 74.100 / 55. 74.100
  libavcodec     57.104.100 / 57.104.100
  libavformat    57. 79.100 / 57. 79.100
  libavdevice    57.  8.100 / 57.  8.100
  libavfilter     6.101.100 /  6.101.100
  libswscale      4.  7.103 /  4.  7.103
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
[png_pipe @ 0x3361c60] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, png_pipe, from 'result.png':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: png, rgb24(pc), 3328x1664 [SAR 2835:2835 DAR 2:1], 25 tbr, 25 tbn, 25 tbc
Input #1, matroska,webm, from 'test.webm':
  Metadata:
    encoder         : libwebm-0.2.1.0
    creation_time   : 2017-09-06T09:39:30.000000Z
  Duration: 00:00:10.04, start: -0.007000, bitrate: 995 kb/s
    Stream #1:0(eng): Video: vp8, yuv420p(progressive), 3328x1664, SAR 1:1 DAR 2:1, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      alpha_mode      : 1
    Stream #1:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
Stream mapping:
  Stream #0:0 (png) -> overlay:main
  Stream #1:0 (vp8_cuvid) -> overlay:overlay
  lut3d -> Stream #0:0 (h264_nvenc)
Press [q] to stop, [?] for help
[vp8_cuvid @ 0x3368fc0] ignoring invalid SAR: 0/0
Impossible to convert between the formats supported by the filter 'graph 0 input from stream 1:0' and the filter 'auto_scaler_1'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #1:0
Conversion failed!