PowerShell script to batch convert FLAC to MP3 using FFmpeg

FlacToMp3.ps1

<#
.SYNOPSIS
    Recursively converts FLAC tracks to MP3 320 kbps using FFmpeg.
    Usage:
    .\convert.ps1 | Converts all FLACs in the current directory to 320k MP3 in a "_Converted" subfolder.
    .\convert.ps1 -DestinationRoot "D:\Music\MP3" -Bitrate 256k | Converts files to the specified path at 256kbps.
#>

[CmdletBinding()]
param(
    [Alias("h", "help")]
    [switch]$ShowHelp,

    [Parameter(Position=0)]
    [string]$DestinationRoot,

    [Parameter(Position=1)]
    [ValidatePattern("^\d+k$")]
    [string]$Bitrate = "320k"
)

if ($ShowHelp) {
    Get-Help $PSCommandPath
    exit
}

if (!(Get-Command ffmpeg -ErrorAction SilentlyContinue)) {
    Write-Host "Error: FFmpeg was not found in your system path." -ForegroundColor Red
    Write-Host "Please install it using the following command (Admin PowerShell):" -ForegroundColor Yellow
    Write-Host "`n    winget install --id Gyan.FFmpeg`n" -ForegroundColor Cyan
    return
}

$sourceRoot = (Get-Location).Path
if ([string]::IsNullOrWhiteSpace($DestinationRoot)) {
    $DestinationRoot = Join-Path $sourceRoot "_Converted"
}

if (!(Test-Path $DestinationRoot)) {
    New-Item -ItemType Directory -Path $DestinationRoot -Force | Out-Null
}

Write-Host "--- Audio Conversion Started ---" -ForegroundColor Cyan
Write-Host "Source: $sourceRoot"
Write-Host "Destination: $DestinationRoot"
Write-Host "Bitrate: $Bitrate" -ForegroundColor Cyan

# Get all unique folders containing FLAC files
$albumDirs = Get-ChildItem -Path $sourceRoot -Recurse -File -Filter *.flac | 
             Select-Object -ExpandProperty DirectoryName -Unique |
             Where-Object { $_ -notlike "*$DestinationRoot*" }

foreach ($dir in $albumDirs) {
    # 1. Path Calculation and Folder Renaming
    $relativeDir = ""
    if ($dir.Length -gt $sourceRoot.Length) {
        $relativeDir = $dir.Substring($sourceRoot.Length).TrimStart([IO.Path]::DirectorySeparatorChar)
    }

    # "Year Album" -> "Year - Album"
    $pathSegments = $relativeDir.Split([IO.Path]::DirectorySeparatorChar)
    $renamedSegments = $pathSegments | ForEach-Object { 
        $_ -replace '^(\d{4})\s+(?!-\s)', '$1 - ' 
    }
    $newRelativeDir = $renamedSegments -join [IO.Path]::DirectorySeparatorChar
    $targetDir = Join-Path $DestinationRoot $newRelativeDir

    if (!(Test-Path $targetDir)) { New-Item -ItemType Directory -Path $targetDir -Force | Out-Null }

    Write-Host "`nFolder: $relativeDir" -ForegroundColor Magenta

    # 2. Cover Art Handling (.jpg, .jpeg, .png)
    $artFile = Get-ChildItem -Path $dir -File | Where-Object { 
        $_.BaseName -eq "Cover" -and ($_.Extension -match '^\.(jpg|jpeg|png)$') 
    } | Select-Object -First 1

    if ($artFile) {
        Copy-Item -Path $artFile.FullName -Destination (Join-Path $targetDir $artFile.Name) -Force
        Write-Host "  [OK] Cover art: $($artFile.Name)" -ForegroundColor Yellow
    }

    # 3. Process FLAC files
    $flacsInDir = Get-ChildItem -Path $dir -Filter *.flac

    foreach ($flac in $flacsInDir) {
        $matchingCue = Join-Path $dir ($flac.BaseName + ".cue")
        
        if (Test-Path $matchingCue) {
            # --- SCENARIO: MONOLITHIC FLAC ---
            Write-Host "  [CUE] Splitting image: $($flac.Name)" -ForegroundColor Cyan
            
            $globalMetadata = @{ PERFORMER = "Unknown Artist"; TITLE = $flac.BaseName; DATE = "" }
            $tracks = @()
            $currentTrack = $null

            Get-Content $matchingCue -Encoding UTF8 | ForEach-Object {
                $line = $_.Trim()
                if ($line -match '^REM DATE (\d+)') { $globalMetadata.DATE = $matches[1] }
                elseif ($line -match '^PERFORMER "(.*)"') { if ($currentTrack) { $currentTrack.Artist = $matches[1] } else { $globalMetadata.PERFORMER = $matches[1] } }
                elseif ($line -match '^TITLE "(.*)"') { if ($currentTrack) { $currentTrack.Title = $matches[1] } else { $globalMetadata.TITLE = $matches[1] } }
                elseif ($line -match '^TRACK (\d+) AUDIO') {
                    if ($currentTrack) { $tracks += $currentTrack }
                    $currentTrack = [ordered]@{ Number = $matches[1]; Title = "Track $($matches[1])"; Artist = $globalMetadata.PERFORMER; Start = 0 }
                }
                elseif ($line -match 'INDEX 01 (\d+):(\d+):(\d+)') {
                    $currentTrack.Start = ([int]$matches[1] * 60) + [int]$matches[2] + ([int]$matches[3] / 75.0)
                }
            }
            if ($currentTrack) { $tracks += $currentTrack }

            for ($i = 0; $i -lt $tracks.Count; $i++) {
                $t = $tracks[$i]
                $startStr = $t.Start.ToString("0.000", [System.Globalization.CultureInfo]::InvariantCulture)
                $duration = if ($i -lt $tracks.Count - 1) { $tracks[$i+1].Start - $t.Start } else { $null }
                
                $outName = "$($t.Number). $($t.Title -replace '[\\/:*?"<>|]', '_').mp3"
                $outPath = Join-Path $targetDir $outName

                $args = @("-ss", $startStr, "-i", "`"$($flac.FullName)`"")
                if ($artFile) { $args += @("-i", "`"$($artFile.FullName)`"") }
                $args += @("-map", "0:a")
                if ($artFile) { $args += @("-map", "1:v", "-c:v", "copy", "-disposition:v", "attached_pic") }
                $args += @("-ab", $Bitrate, "-id3v2_version", "3", "-metadata", "title=$($t.Title)", "-metadata", "artist=$($t.Artist)", "-metadata", "album=$($globalMetadata.TITLE)", "-metadata", "date=$($globalMetadata.DATE)", "-metadata", "track=$($t.Number)/$($tracks.Count)")
                if ($duration) { $args += @("-t", $duration.ToString("0.000", [System.Globalization.CultureInfo]::InvariantCulture)) }
                $args += "`"$outPath`""

                cmd /c "ffmpeg -hide_banner -loglevel error -y $args"
            }
        }
        else {
            # --- SCENARIO: SEPARATE TRACKS ---
            Write-Host "  [FILE] Converting: $($flac.Name)" -ForegroundColor Green
            $outPath = Join-Path $targetDir ($flac.BaseName + ".mp3")

            $args = @("-i", "`"$($flac.FullName)`"")
            if ($artFile) { $args += @("-i", "`"$($artFile.FullName)`"") }
            $args += @("-map", "0:a")
            if ($artFile) { $args += @("-map", "1:v", "-c:v", "copy", "-disposition:v", "attached_pic") }
            $args += @("-ab", $Bitrate, "-map_metadata", "0", "-id3v2_version", "3", "-y", "`"$outPath`"")
            
            cmd /c "ffmpeg -hide_banner -loglevel error $args"
        }
    }
}

Write-Host "`nConversion Complete!" -ForegroundColor Green