Simple script to convert any audio/video to M4A using drag'n'drop on shortcut after first run

convert2m4a.ps1

#Requires -Version 5.1
Set-StrictMode -Version Latest

if ($args.Length -eq 0) {
    $shell = New-Object -ComObject WScript.Shell
    $shortcut = $shell.CreateShortcut($PSCommandPath.Replace(".ps1", "") + " (Drag'n'Drop).lnk")
    $pwsh = "pwsh"
    if (!$(Get-Command pwsh -ErrorAction SilentlyContinue)) {
        Write-Output "PowerShell (pwsh) not found, falling back to Windows PowerShell (powershell)"
        $pwsh = "powershell"
    }
    $shortcut.TargetPath = $pwsh
    $shortcut.Arguments = "-NoLogo -NoExit -NoProfile -ExecutionPolicy Bypass -Command ""& { $PSCommandPath `$args }"""
    $shortcut.Save()
    exit 0
}

if ($args.Length -ne 1) {
    Write-Error "Expected exactly 1 argument, but found $($args.Length)"
    exit 1
}

if (!$(Get-Command ffmpeg -ErrorAction SilentlyContinue) -or !$(Get-Command ffprobe -ErrorAction SilentlyContinue)) {
    $consent = Read-Host "This script requires FFmpeg, do you want to install it using winget (winget install --id Gyan.FFmpeg -e)? [y/n]"

    if ($consent.Trim().ToLower() -ne "y") {
        Write-Output "Please install FFmpeg manually and try again"
        exit 0
    }

    if (!$(Get-Command winget -ErrorAction SilentlyContinue)) {
        Write-Error "It seems like you don't have winget installed, either update your Windows version or get it from https://github.com/microsoft/winget-cli and try again"
        exit 1
    }
    
    Write-Output "Trying to install FFmpeg"
    winget install --id Gyan.FFmpeg -e

    if ($?) {
        Write-Output "Successfully installed FFmpeg"
    } else {
        Write-Error "Failed to install FFmpeg"
        exit 1
    }
}

$inputFile = [System.IO.Path]::GetFullPath([System.IO.Path]::Combine($PSScriptRoot, $args[0]))
$outputFile = [System.IO.Path]::ChangeExtension($inputFile, ".m4a")

if (!(Test-Path $inputFile)) {
    Write-Error "Input file not found: ""$inputFile"""
    exit 1
}

if (Test-Path $outputFile) {
    Write-Error "Output file already exists: ""$outputFile"""
    exit 1
}

$ffprobe = ffprobe -loglevel warning -print_format json -show_format -show_streams "$inputFile" | ConvertFrom-Json
$audioChannelCount = ($ffprobe.streams | Where-Object codec_type -eq "audio")[0].channels
$audioBitrate = 160
if ($audioChannelCount -gt 2) {
    $audioBitrate = 64 * $audioChannelCount
}

ffmpeg -benchmark -i "$inputFile" -map "0:a" -c:a "aac" -b:a "${audioBitrate}k" -movflags +faststart -map_metadata "-1" -map_chapters "-1" -metadata:g title="" -metadata:g description="" "$outputFile"

if ($?) {
    Write-Output "`nSuccessfully converted ""$inputFile"" to ""$outputFile"" with FFmpeg`n"
    exit 0
} else {
    Write-Error "`nFailed to convert ""$inputFile"" to ""$outputFile"" with FFmpeg`n"
    exit 1
}