encoder.ps1

param (
	[string]$fps = "30",
	[Parameter(Mandatory=$true)][string]$File,
	[Parameter(Mandatory=$true)][string]$Start,
	[Parameter(Mandatory=$true)][string]$Duration
)
$Size = 7.5*8000
$Bitrate=$Size/$duration
write-output "$fps fps, $duration duration, $Bitrate bitrate."

ffmpeg -hide_banner -loglevel info -an -ss $Start -t $Duration -y -i $File -c:v libvpx-vp9 -b:v ${BITRATE}k -pass 1 -row-mt 1 -r $FPS -f webm - > $null
Invoke-Expression "ffmpeg -hide_banner -loglevel info -ss $Start -t $Duration -i $File -c:v libvpx-vp9 -b:v ${BITRATE}k -c:a libopus -b:a 128k -pass 2 -row-mt 1 -r $FPS -f webm ${File}.webm"