Handling metadata when using Reaper for mastering

Metadata handling matters more than it sounds in mastering. A well-organized, searchable archive is essential for any professional studio. Clients often request files years after the process is complete, and proper metadata ensures those files can actually be found.

Missing or incorrect metadata also creates real problems for digital distribution. And despite the streaming numbers, CDs are still a meaningful part of the industry. Musicians care about CD-TEXT, which makes accurate DDP metadata a standard part of the job.

One reason I keep coming back to Reaper for mastering is that it handles everything in a single project: processing, sequencing, and exporting. That means I can store a release's metadata directly in the timeline and automate the exports.

The way I manage this is by attaching metadata directly to Regions.

Why Regions?

Working with regions in Reaper is a natural fit for mastering, especially for time-bounded material like a single track, an album, or movements in a classical piece.

Even for a gapless record, regions help visualize where specific parts begin and end. They let you jump between sections instantly and make cuts to process sections separately if needed, even if you ultimately export everything as a single continuous file.

The Metadata Template

I took a cue from Reaper's built-in system designed for DDP export and developed a standard region naming template.

#TITLE=Title|PERFORMER=Artist|COMPOSER=Composer|LYRICIST=Lyricist|ISRC=PTKNU2600001|VERSION=1|VINYL=A1

My region title template

For each region, I paste this template and edit the fields for that specific track. This allows me to input granular data that can be retrieved later using wildcards during the render process.

Breakdown of Fields

Standard Fields: TITLE, PERFORMER, COMPOSER, LYRICIST, and ISRC are self-explanatory standard tags.
VERSION: Used internally. If a track undergoes revisions, I can trace the version number in the filename.
VINYL: Since I frequently master for vinyl, this field lets me designate sides (e.g., A1, A2, B1, C4). For streaming, the region ID determines track ordering (1, 2, 3...) but for vinyl releases I extract the wildcard from this field to determine sequencing on the physical medium.

This way, separate sequencing for digital and vinyl is always saved in the project.

Global Release Metadata

Region metadata handles track-level details, but I also need fields for the entire release (e.g., Album Artist, Album Title).

I store this in the Project Settings:

Go to File > Project Settings.
Click the Notes tab.
Fill in the "Title" (Album Name) and "Author" (Album Artist) fields.

Exporting Digital Files

Once the regions are named, the next step is instructing Reaper to use that text as metadata.

In the Render to File window:

Toggle on the Metadata... option.
Use wildcards to map your region data to ID3/WAV tags.
For example, to map the Track Title, you would use: $region(#TITLE)[|]
Note on Syntax: The [|] at the end of the wildcard tells Reaper to stop reading at the pipe character | used in our region template.

Reaper Render Metadata with wildcards

Image 1. Reaper Render Metadata window with the wildcards template we currently use at Knurl Mastering.

File Naming Pattern

I also use these wildcards for the actual filenames. Our studio's standard naming pattern looks like this:

$region(PERFORMER)[|] - $regionnumber $region(#TITLE)[|] v$region(VERSION)[|]

This automatically generates filenames like: Artist Name - 01 Song Title v1.wav

Handling DDPs and CD-TEXT

The system above works well for digital files, but Audio CDs (DDP images) require a different approach. DDPs rely on specific markers to identify track start points, indices, and CD-TEXT.

Reaper has native DDP support, but manually placing markers and typing out metadata for them is tedious and prone to error. Fortunately, Reaper allows for scripting.

I wrote a Lua script that automates this entire process. It reads your Region names (which you've already formatted), cleans up special characters, and converts them into the specific markers required for a valid DDP.

This script does two main things:

Converts Regions to Markers: It maps your region starts to track markers (#) and handles the special start (!) and end (@) markers required by the DDP standard.
Sanitizes Text: CD-TEXT is very strict about character sets (ASCII). The script automatically transliterates characters like "ç" to "c" or "ñ" to "n". While not linguistically perfect, it prevents CD players from displaying garbage characters or rejecting the text entirely.

--[[
* ReaScript Name: Convert Regions to DDP Markers
* Description: Creates DDP markers (!, Tracks, @) with full metadata integration and text sanitization.
* Author: Knurl Mastering
--]]

local is_new_value, filename, section_ID, command_ID, mode, resolution, val = reaper.get_action_context()

-----------------------------------------------------------
-- 1. TOOLBAR FLASH LOGIC
-----------------------------------------------------------
local flash_duration = 0.1 
local start_time = 0

function MonitorFlash()
	local now = reaper.time_precise()
	if now - start_time < flash_duration then
		reaper.defer(MonitorFlash) 
	else
		reaper.SetToggleCommandState(section_ID, command_ID, 0)
		reaper.RefreshToolbar2(section_ID, command_ID)
	end
end

function TriggerFlash()
	reaper.SetToggleCommandState(section_ID, command_ID, 1)
	reaper.RefreshToolbar2(section_ID, command_ID)
	start_time = reaper.time_precise()
	MonitorFlash()
end

-----------------------------------------------------------
-- 2. TEXT SANITIZATION
-----------------------------------------------------------
local replacements = {
	["á"]="a", ["à"]="a", ["ã"]="a", ["â"]="a", ["ä"]="a", ["å"]="a",
	["é"]="e", ["è"]="e", ["ê"]="e", ["ë"]="e",
	["í"]="i", ["ì"]="i", ["î"]="i", ["ï"]="i",
	["ó"]="o", ["ò"]="o", ["õ"]="o", ["ô"]="o", ["ö"]="o",
	["ú"]="u", ["ù"]="u", ["û"]="u", ["ü"]="u",
	["ç"]="c", ["ñ"]="n", ["ý"]="y",
	["Á"]="A", ["À"]="A", ["Ã"]="A", ["Â"]="A", ["Ä"]="A", ["Å"]="A",
	["É"]="E", ["È"]="E", ["Ê"]="E", ["Ë"]="E",
	["Í"]="I", ["Ì"]="I", ["Î"]="I", ["Ï"]="I",
	["Ó"]="O", ["Ò"]="O", ["Õ"]="O", ["Ô"]="O", ["Ö"]="O",
	["Ú"]="U", ["Ù"]="U", ["Û"]="U", ["Ü"]="U",
	["Ç"]="C", ["Ñ"]="N", ["Ý"]="Y"
}

function sanitize_text(str)
	if not str then return "" end
	-- Step A: Replace accented chars
	for k, v in pairs(replacements) do
		str = string.gsub(str, k, v)
	end
	-- Step B: Allow # = | and standard punctuation
	str = string.gsub(str, "[^%w%s%-%_%.%,%!%?%'%\"%(%)%#%=%|]", "")
	return str
end

-----------------------------------------------------------
-- 3. METADATA HELPERS
-----------------------------------------------------------
function get_project_title()
	local retval, title = reaper.GetSetProjectInfo_String(0, "PROJECT_TITLE", "", false)
	if retval and title ~= "" then
		return sanitize_text(title)
	else
		return "Unknown Album"
	end
end

function get_project_author()
	local retval, author = reaper.GetSetProjectInfo_String(0, "PROJECT_AUTHOR", "", false)
	if retval and author ~= "" then
		return sanitize_text(author)
	else
		return "Unknown Artist"
	end
end

function create_colored_marker(pos, name, id)
	-- Dark Grey (64, 64, 64)
	local r, g, b = 64, 64, 64
	local color = reaper.ColorToNative(r, g, b) | 0x1000000
	
	reaper.AddProjectMarker2(0, false, pos, 0, name, id, color)
end

-----------------------------------------------------------
-- 4. MAIN LOGIC
-----------------------------------------------------------
function main()
	-- CHECK: Do regions exist?
	local ret, num_markers, num_regions = reaper.CountProjectMarkers(0)
	if num_regions == 0 then return end 
	
	TriggerFlash()
	reaper.Undo_BeginBlock()

	local i = 0
	local regions_to_process = {}
	local last_region_end = 0

	-- LOOP: Gather all Regions
	while true do
		local retval, isrgn, pos, rgnend, name, markrgnindexnumber = reaper.EnumProjectMarkers(i)
		if retval == 0 then break end
		
		if isrgn then
			table.insert(regions_to_process, {
				pos = pos,
				name = name,
				id = markrgnindexnumber
			})
			
			-- Find the absolute end of the album
			if rgnend > last_region_end then
				last_region_end = rgnend
			end
		end
		i = i + 1
	end

	-- A. CREATE START MARKER (ID 99)
	create_colored_marker(0, "!", 99)

	-- B. CREATE TRACK MARKERS
	for _, rgn in ipairs(regions_to_process) do
		local clean_name = sanitize_text(rgn.name)
		create_colored_marker(rgn.pos, clean_name, rgn.id)
	end

	-- C. CREATE END MARKER
	-- Format: @ALBUM|PERFORMER=Artist
	local album_title = get_project_title()
	local album_artist = get_project_author()
	local end_marker_name = "@" .. album_title .. "|PERFORMER=" .. album_artist
	
	-- ID: Number of Regions + 1
	local end_marker_id = num_regions + 1
	
	create_colored_marker(last_region_end, end_marker_name, end_marker_id)

	reaper.Undo_EndBlock("Create DDP Markers", -1)
end

main()