PowerShell script to convert SRT files to VTT

ConvertTo-VTT.ps1

# Reads SRT and writes VTT
param (
    [Parameter(Mandatory = $true)][string]$SrcPath
    )

# Get all of the matching file names
$MatchingFileNames = (Get-ChildItem $SrcPath -File) | sort-Object Name

# walk through the list of files
foreach($MatchingFileName in $MatchingFileNames) {
    $file_data = Get-Content $MatchingFileName

    # Verify that we are reading a SRT file
    $IsSRT = $file_data[0] -like '1'

    if ($IsSRT -eq $True) {
        # Another check to see if we are reading a SRT file
        $ThisTime = $file_data[1].Split(" ")

        if ($ThisTime.Length -eq 3) {
            $IsSRT = $ThisTime[1] -eq "-->"
        } else {
            $IsSRT = $false
        }
    }

    if ($IsSRT -eq $True) {
        # Generate the destination filename
        $srtFilename = [io.path]::ChangeExtension($MatchingFileName.FullName, 'vtt')

        $new_data = New-Object System.Collections.Generic.List[System.Object]
        $new_data.Add("WEBVTT")
        $new_data.Add("")

        Write-Host ('Reading ' + $MatchingFileName.FullName )
        $CurentLine = 1

        while ($CurentLine -lt $file_data.Length) {
            $percent = ($CurentLine * 100 / $file_data.Length)

            Write-Progress -Activity "Processing $MatchingFileName.FullName to $srtFilename"  -Status "$percent% complete" -PercentComplete $percent

            $ThisLine = $file_data[$CurentLine]

            $ThisTime = $ThisLine.Split(" ")

            if ($ThisTime.Length -eq 3) {
                if ($ThisTime[1] -eq "-->") {
                    # Change the time format from SRT to VTT
                    $ThisLine = $ThisLine.Replace(',', '.')

                    $new_data.Add($ThisLine)

                    $CurentLine++

                    # Read the next set of lines for the caption
                    # Treat as caption until the next blank line

                    $caption = $file_data[$CurentLine]
                    # $currentCaption = ''
                    while ($caption -ne '' -and $CurentLine -lt $file_data.Length) {
                        $new_data.Add($caption)

                        $caption = $file_data[++$CurentLine]
                    }

                    $new_data.Add($caption)
                }
            }
            $CurentLine++
        }

        # Write out the converted data
        Write-Host ('Writing ' + $srtFilename )
        Out-File -FilePath $srtFilename -InputObject $new_data
    }
}