Webm encoding fails with ffmpeg

[woolwood]

mpv version and platform

OS: Ubuntu Linux 19.04 amd mpv:

mpv 0.29.0-326-g91c1691b35 Copyright © 2000-2019 mpv/MPlayer/mplayer2 projects
 built on Thu May  9 01:10:57 CEST 2019
ffmpeg library versions:
   libavutil       56.26.101
   libavcodec      58.52.101
   libavformat     58.27.103
   libswscale      5.4.100
   libavfilter     7.50.100
   libswresample   3.4.100
ffmpeg version: N-93814-g48539b62fc

ffmpeg binary:

ffmpeg version N-93799-gc636dc9 Copyright (c) 2000-2019 the FFmpeg developers
built with clang version 8.0.0-3 (tags/RELEASE_800/final)
configuration: --prefix=/home/adriaan/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/adriaan/ffmpeg_build/include --extra-ldflags=-L/home/adriaan/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/adriaan/bin --enable-gpl --enable-libaom --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --cc=clang --enable-nonfree
libavutil      56. 26.101 / 56. 26.101
libavcodec     58. 52.101 / 58. 52.101
libavformat    58. 27.103 / 58. 27.103
libavdevice    58.  7.100 / 58.  7.100
libavfilter     7. 50.100 /  7. 50.100
libswscale      5.  4.100 /  5.  4.100
libswresample   3.  4.100 /  3.  4.100
libpostproc    55.  4.100 / 55.  4.100

Description

Thanks to your earlier help, encoding to mp4 using ffmpeg works. I noticed that encoding to vp8/vp9 webm's fails

[webm_ffmpeg] Command subprocess: argument args has incompatible type.
[webm_ffmpeg] Command failed! Reason:  invalid parameter  Killed by us?  no 
[webm_ffmpeg] Command stdout:  
[webm_ffmpeg] nil 

Log file

log.txt

[ekisu]

Seems like GitHub just doesn't want to do its work and close the issue. Fixed in 98f8d4f.