The command I used was :
C:\cmd\ffmpeg\bin\ffmpeg.exe -i "C:\Users\user\Dropbox\Workspace - C#\SnowflakeGenerator\out\out%d.png" -c:v libvpx -b:v 1M "C:\Users\user\Dropbox\Workspace - C#\SnowflakeGenerator\video.webm" -y
The output was:
ffmpeg version N-82889-g54931fd Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
libavutil 55. 43.100 / 55. 43.100
libavcodec 57. 68.100 / 57. 68.100
libavformat 57. 61.100 / 57. 61.100
libavdevice 57. 2.100 / 57. 2.100
libavfilter 6. 68.100 / 6. 68.100
libswscale 4. 3.101 / 4. 3.101
libswresample 2. 4.100 / 2. 4.100
libpostproc 54. 2.100 / 54. 2.100
Input #0, image2, from 'C:\Users\yb5243yv\Dropbox\Workspace - C#\SnowflakeGenerator\out\out%d.png':
Duration: 00:00:21.04, start: 0.000000, bitrate: N/A
Stream #0:0: Video: png, rgba(pc), 1000x1000 [SAR 3779:3779 DAR 1:1], 25 fps, 25 tbr, 25 tbn, 25 tbc
[libvpx @ 0000000000be89c0] v1.6.0
[libvpx @ 0000000000be89c0] Transparency encoding with auto_alt_ref does not work
Stream mapping:
Stream #0:0 -> #0:0 (png (native) -> vp8 (libvpx))
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
The error is:
[libvpx @ 0000000000be89c0] Transparency encoding with auto_alt_ref does not work
and
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
I'm not sure exactly what is causing the issue, I followed this tutorial, however they did not mention the error. I should mention that I am not using audio, so I left the audio encoder out (I did try it with the audio encoder to make sure, and that was not the problem)
Like the error msg says, Transparency encoding with auto_alt_ref does not work, so
ffmpeg.exe -i "out%d.png" -c:v libvpx -b:v 1M -auto-alt-ref 0 "video.webm" -y