VideoToGif.ps1

using namespace System.IO;
$ErrorActionPreference = 'Stop'

function VideoToGif{
    Param(
        [Parameter(Mandatory=$true)][string] $InFile,
        [Parameter(Mandatory=$true)][string] $OutFile,
        [int]$Width=320,
        [int]$Height=-1,
        [double]$Start=0.0,
        [double]$Length=0)
    $paletteFileName = [Path]::Combine([Path]::GetTempPath(), [Path]::GetRandomFileName()) + ".png";
    ffmpeg -y -ss $Start -t $Length -i "$InFile" -filter_complex "[0:v]scale=${Width}:${Height}[v];[v]palettegen" "$paletteFileName"
    if(!$?) { return $null }
    ffmpeg -y -ss $Start -t $Length -i "$InFile" -i "$paletteFileName" -filter_complex "[0:v]scale=${Width}:${Height}[v];[v][1:v]paletteuse" "$OutFile"
    $rv = $?    
    [File]::Delete($paletteFileName)
    if ($rv) { return $OutFile } else { return $null }
}