Change framerate for OGM Chapter files

Sync-Chapters.ps1

function Sync-Chapters {

    [CmdletBinding()]
    Param(
        [Parameter(Mandatory=$false)]
        [double]$SourceFPS,
        [Parameter(Mandatory=$false)]
        [double]$TargetFPS,
        [Parameter(Mandatory=$false)]
        [double]$milliseconds,
        [Parameter(Mandatory=$true)]
        $file
    )

    $file = get-childitem -literalpath $file
    $content = Get-Content -literalpath $file

    if ($SourceFPS -and $TargetFPS) {
        if (-not $SourceFPS -or -not $TargetFPS) {
            Write-Error "Parameters `$SourceFPS and `$TargetFPS are required for this process."
            return
        }
        for($i=0; $i -le $content.Length; ++$i)
        {

            if($content[$i] | Select-String -Pattern "\d+:\d+:\d+\.\d+")
            {
                $name = $content[$i].Split("=")[0]
                $time = $content[$i].Split("=")[1]
                $time_timespan = ([datetime] $time).TimeOfDay
    
                $diff = $SourceFPS / $TargetFPS
                $new_time = "{0:hh\:mm\:ss\.fff}" -f ($time_timespan * $diff)
                $content[$i] = $name + "=" + $new_time
            }
        }
    
        $content | Set-Content (join-path $($file.DirectoryName) "$($file.basename).FIXED$($file.extension)")

    } elseif ($milliseconds) {
        if (-not $milliseconds) {
            Write-Error "`$milliseconds is required for this process."
            return
        }
        for($i=0; $i -le $content.Length; ++$i)
        {
            if($content[$i] | Select-String -Pattern "\d+:\d+:\d+\.\d+")
            {
                if ($i -gt 0) {
                    $name = $content[$i].Split("=")[0]
                    $time = $content[$i].Split("=")[1]
                    $time_timespan = ([datetime] $time).TimeOfDay
                    $new_time = "{0:hh\:mm\:ss\.fff}" -f ($time_timespan.add([System.TimeSpan]::FromMilliseconds($milliseconds)))
                    $content[$i] = $name + "=" + $new_time
                }
                
            }
        }
    
        $content | Set-Content (join-path $($file.DirectoryName) "$($file.basename).FIXED$($file.extension)")

    } else {
        Write-Error "You must specify parameters for either Process 1 (`$SourceFPS and `$TargetFPS) or Process 2 (`$milliseconds)."
    }
}