Convert-MKVtoMP4.ps1

<#
.SYNOPSIS
  For a given path, converts any MKV files to MP4 format using ffmpeg.
.EXAMPLE
  PS C:\> Convert-MKVtoMP4 c:\temp
  Explanation of what the example does
.PARAMETER Path 
  Path that will be processed.
.PARAMETER Extension
  Extension to search for, defaults to MKV
#>
#List the parameters we expect to get. Path is mandatory, and Extension has a default value if not specified
Param([Parameter(Mandatory=$true)]$Path, $Extension="*.mkv")
#Find the drive letter
$driveLetter = Split-Path $Path -Qualifier
#Make the recycle bin path
$recyclePath = Join-Path $driveLetter "@Recycle"
#Get the list of MKV files in an array
$fileList = Get-ChildItem $Path -Filter $Extension
foreach ($file in $fileList) {
  $newName = $file.BaseName + ".mp4"
  #EchoArgs would be replaced with ffmpeg path
  EchoArgs.exe -i $file.Name -codec copy $newName
  #Take off the -WhatIf to make these actually delete
  Remove-Item $file.FullName -WhatIf
  #Recursively search the recycle bin on that drive and delete the file if found
  Get-ChildItem $recyclePath -Filter $file.Name -Recurse | Remove-Item -WhatIf
}