PowerShell script to split video into multiple files using ffmpeg

splitvideo.ps1

param (
    [Parameter(Mandatory=$true)]
    [string]$inVideoPath,

    [Parameter(Mandatory=$false)]
    [string]$outVideoDirectory
)

$ErrorActionPreference = "Stop"
$ffmpegCommand = 'ffmpeg'

# Validation

if (!(Test-Path $inVideoPath)) {
    throw 'Input file does not exist: ' + $inVideoPath
}

if (!(Test-Path $inVideoPath -PathType Leaf)) {
    throw 'Input path is not a file: ' + $inVideoPath
}

$fileExtension = [io.path]::GetExtension($inVideoPath)
if (!$fileExtension) {
    throw 'Input file has no extension: ' + $inVideoPath
}

if ($outVideoDirectory) {
    if (!(Test-Path $outVideoDirectory)) {
        throw 'Output path does not exist: ' + $outVideoDirectory
    }

    if (!(Test-Path $outVideoDirectory -PathType Container)) {
        throw 'Output path is not a directory: ' + $outVideoDirectory
    }
}


# Input

Write-Host 'Enter split points in the format "m:ss[ filename]". Use a blank line to finish.'

$inlines = @()
while ($true) {
    $inline = Read-Host
    if ($inline -eq '') {
        break
    }

    $inlines += $inline
}

$splitPoints = @()
foreach ($inline in $inlines) {
    $regex = '^\s*(\d+:[0-5][0-9]+(.[0-9]+)?)(\s+([^' + [Regex]::Escape(-join [System.Io.Path]::GetInvalidFileNameChars()) + ']+))?\s*$'
    $valid = $inline -match $regex
    if (!$valid) {
        throw 'Invalid format: ' + $inline
    }

    $splitPoint = @{
        Offset = $Matches[1]
        FileName = $Matches[3]
    }
    
    if (!$splitPoint.FileName) {
        $escapedOffset = [Regex]::Replace($splitPoint.Offset, '[.' + [Regex]::Escape(-join [System.Io.Path]::GetInvalidFileNameChars()) + ']', '_')
        $splitPoint.FileName = [io.path]::GetFileNameWithoutExtension($inVideoPath) + " " + $escapedOffset
    }

    # TODO: Detect duplicate file names in the list

    $splitPoints += $splitPoint
}


# Preparation

$commands = @()
for ($i = 0; $i -lt $splitPoints.Length; ++$i) {
    $splitPoint = $splitPoints[$i]

    $outVideoFileName = if ([io.path]::HasExtension($splitPoint.FileName)) { $splitPoint.FileName } else { [io.path]::ChangeExtension($splitPoint.FileName, $fileExtension) }
    $outVideoPath = if ($outVideoDirectory) { Join-Path -Path $outVideoDirectory -ChildPath $outVideoFileName } else { $outVideoFileName }
    
    # TODO: Maybe move this check closer to when we will actually create the file
    if (Test-Path $outVideoPath -PathType Leaf) {
        throw 'Destination file already exists: ' + $outVideoPath
    }

    $toParameter = if ($i -lt $splitPoints.Length - 1) { "-to $($splitPoints[$i + 1].Offset) " } else { '' }
    $command = @{
        Program = $ffmpegCommand
        Arguments = "-loglevel warning -i ""$inVideoPath"" -c copy -ss $($splitPoint.Offset) $($toParameter)""$outVideoPath"""
    }

    $commands += $command
}

if (!(Get-Command $ffmpegCommand -ErrorAction SilentlyContinue)) {
    throw "$ffmpegCommand not found in PATH"
}

# Execution

foreach ($command in $commands) {
    # TODO: On error, clean up

    $process = New-Object System.Diagnostics.Process
    $process.StartInfo.FileName = $command.Program
    $process.StartInfo.Arguments = $command.Arguments
    $process.StartInfo.UseShellExecute = $false
    $process.StartInfo.RedirectStandardError = $true
    $process.StartInfo.WorkingDirectory = Get-Location

    Write-Host ($process.StartInfo.FileName + ' ' + $process.StartInfo.Arguments)
    $process.Start() > $null
    $output = $process.StandardError.ReadToEnd()
    $process.WaitForExit()
    
    if ($output.Trim()) {
        Write-Host $output
    }

    if ($process.ExitCode -ne 0) {
        throw "$($process.StartInfo.FileName) exited with code $($process.ExitCode)"
    }
}