Get-ChildItem -Filter *.mkv | ForEach-Object {
  $in  = $_.FullName
  $out = "$($_.BaseName)_8bit_clean.mkv"
  if (Test-Path $out) { return }

  # index + language pour TOUS les streams qui ont une langue
  $streamLangs = & ffprobe -v error `
    -show_entries stream=index:stream_tags=language `
    -of csv=p=0 "$in"

  $args = @(
    "-i", $in,
    "-map", "0",
    "-map_metadata", "-1",
    "-map_chapters", "-1",
    "-metadata", "encoder=",
    "-c:v", "libx265",
    "-pix_fmt", "yuv420p",
    "-x265-params", "profile=main",
    "-crf", "20",
    "-preset", "slow",
    "-c:a", "copy",
    "-c:s", "copy"
  )

  foreach ($line in $streamLangs) {
    # format csv: index,language
    $parts = $line.Split(',')
    if ($parts.Count -ge 2) {
      $idx  = $parts[0].Trim()
      $lang = $parts[1].Trim()
      if ($idx -match '^\d+$' -and $lang -and $lang -ne "N/A") {
        $args += @("-metadata:s:$idx", "language=$lang")
      }
    }
  }

  $args += $out
  & ffmpeg @args
}