Powershellとわかりあえなかったffmpegで画像切りだすスクリプト

_generate_images.ps1

Param(
    [Parameter(Mandatory=$true,
               Position=0,
               HelpMessage="Literal path to movie file.")]
    [ValidateNotNullOrEmpty()]
    [string]
    $MovieFile,
    [Parameter(Mandatory=$true,
               HelpMessage="Name of directory for generating image files.")]
    [ValidateNotNullOrEmpty()]
    [string]
    $DirectoryName,
    [Parameter(Mandatory=$true)]
    [UInt32]
    $TargetFrameNumber,
    [Parameter()]
    [UInt32]
    $NumberOfImages = 42,
    [Parameter()]
    [UInt32]
    $MovieFramerate = 60,
    [Parameter()]
    [ValidateSet("clock", "cclock", "none")]
    [string[]]
    $ImageRotation = "clock"
)

if ((Test-Path -Path $DirectoryName) -and (Test-Path -Path $DirectoryName -PathType Leaf)) {
    Write-Error $DirectoryName " exists and not directory. exit."
    Exit
}

if (-not(Test-Path -Path $DirectoryName -PathType Container)) {
    Write-Verbose ("Create Directory: {0}" -f $DirectoryName)
    try {
        New-Item -Path $DirectoryName -ItemType Directory
    }
    catch {
        throw $_.Exception.Message
    }
}

$gci_result = Get-ChildItem -Path $DirectoryName -Filter *.png
if ($gci_result.Length -ne 0) {
    try {
        Write-Verbose ("Try to remove images: {0} for {1}" -f $DirectoryName, $gci_result.Length)
        Remove-Item -Path $DirectoryName -Filter *.png
    }
    catch {
        throw $_.Exception.Message
    }
}

$HalfOfImages = [int][System.Math]::Floor(($NumberOfImages / 2))
Write-Verbose ("Images: {0} / 2 -> {1}" -f $NumberOfImages, $HalfOfImages)
$ss = (($TargetFrameNumber - $HalfOfImages) / $MovieFramerate)
$ss = [Math]::Round($ss, 3)


$clockwise = @("-vf", ('transpose={0}' -f $ImageRotation))
if ($ImageRotation -eq "none") {
    $clockwise = @()
}

$param = @("-ss", $ss, "-i", $MovieFile) + $clockwise + @("-frames:v", $NumberOfImages, ("{0}\%04d.png" -f $DirectoryName))
Write-Host $param

& ffmpeg $param