Mapset Verifier (MV) is a desktop app which tests quantifyable issues in beatmapsets from osu!, such as unsnapped objects and unused files. Many of these issues would otherwise disqualify the map from being ranked. Although mainly aimed at Beatmap Nominators, this can also be used by mapset creators and reviewers to speed up the ranking process.

MV is a successor to the game's built-in AiMod and Sieg's Modding Assistant, providing more features and greater scalability. Some examples include auto-updates, plugin support, and integrated documentation and diff utilities.

This is currently being ported to osu!lazer. You can track its progress here!

Note

Some issues are not easily quantified, especially ones related to metadata and timing; far from everything is covered. Also, false positives and false negatives may occur, as with any similar tool. So always use your own judgement and be critical about what the program points out, especially warnings.

Download

See the latest release. On Windows, get the exe file. On Linux, get the tar.gz / use this package on archlinux.

Version	Date Released	Windows	Linux
1.8.2	2021-09-21
1.8.0	2021-09-14
1.7.2	2020-10-07
1.7.1	2020-10-03
1.7.0	2020-09-28
1.6.6	2020-08-04
1.6.5	2020-07-03

Common Problems

• Windows protected pc

  • Solution: More info > Run anyway OR Right click installer > Properties > Unblock
  • Reason: Installer has no signed certificate (costs)

• Stuck on install screen when reinstalling

  • Solution: Uninstall before reinstalling
  • Reason: Limitation in electron-builder

• Javascript error ENOENT, no MapsetVerifierBackend.exe in /app/api/win-x86

  • Solution: Uninstall, reinstall, then whitelist this exe in your antivirus before running again
  • Reason: Antivirus false positive, deletes the backend (part that does checks) on first run

Feature Comparison

Feature	Mapset Verifier	Modding Assistant	AiMod
Difficulty Interpretation	✅ (Option, Name, SR)	✅ (Name, SR)	✅ (SR)
Snapshots	✅ (Automatic)	✅ (Manual)	⬜️
Integrated Documentation	✅	✅ (RC Snippets)	⬜️
Timeline Comparison	✅	✅ (Taiko-only)	⬜️
Song folder detection	✅	⬜️	✅
Automatic Updates	✅ (Windows-only)	⬜️	✅
Verbose Mode	✅	⬜️	✅
Plugin Support	✅	⬜️	⬜️
Open Source	✅	⬜️	⬜️
Difficulty Graph	✅	✅ (Outdated SR)	⬜️

Examples of fixed false positives/negatives

Modding Assistant

• counting extended break times as drain time.
• failing to account for minimum SV (0.1x).
• misinterpreting hit sounds on slider bodies as hit sounds on heads/tails.
• completely ignoring storyboard variables and animation frames.

AiMod

• incorrectly detecting unsnaps on slider tails < 2 ms off
• not accounting for stacking.
• using a vastly outdated star rating system, saying you need an easy/normal when you already have one.
• using inaccurate playfield measurements to detect offscreen hit objects.

Plugins

Add check DLLs to %APPDATA%/Mapset Verifier Externals/checks to have them load in just like the default checks. To create these DLLs, have a look at how MapsetChecks was created. This is probably also useful.

Third-party plugins (that I'm aware of):

• CatchCheck by -Keitaro, adds osu!catch-specific checks.
• MapsetChecksCatch by Greaper, adds osu!catch-specific checks.
• MVTaikoChecks by Hivie, adds osu!taiko-specific checks.

In general, do be careful about which check plugins you use, as they can be malicious. The plugins are executed by the back end of the application, so they can pretty much do anything the rest of the application can.

Technical Overview

The backend is written in C#/.NET, with a simple ASP.NET Core server. The frontend is an Electron desktop application written in HTML, CSS, and JS/JQuery. The server-client communication is done with SignalR. Upon selecting a mapset, the frontend requests tabs to be rendered, and the backend returns HTML.

Checks (last updated 2021-09-14)

General

Category	Issue Message
Resources	Missing background.
Resources	Too high or low background resolution.
Resources	Inconsistent video usage.
Resources	Overlay layer usage.
Resources	Too high sprite resolution.
Resources	Inconsistent video offset.
Resources	Too high video resolution.
Metadata	Inconsistent metadata.
Metadata	Incorrect marker format.
Metadata	Incorrect marker spacing.
Metadata	BMS used as source.
Metadata	Incorrect format of (TV Size) / (Game Ver.) / (Short Ver.) / (Cut Ver.) / (Sped Up Ver.) in title.
Metadata	Unicode in romanized fields.
Metadata	Missing genre/language in tags.
Files	Issues with updating or downloading.
Files	0-byte files.
Files	Unused files.
Audio	Audio channels in video.
Audio	More than 20% unused audio at the end.
Audio	Too high or low audio bitrate.
Audio	Frequent finish hit sounds.
Audio	Delayed hit sounds.
Audio	Incorrect hit sound format.
Audio	Imbalanced hit sounds.
Audio	Too short hit sounds.
Audio	Multiple or missing audio files.
Audio	Incorrect audio format.

All Modes

Category	Issue Message
Timing	Concurrent or conflicting timing lines.
Timing	First line toggles kiai or is inherited.
Timing	Inconsistent uninherited lines, meter signatures or BPM.
Timing	Unsnapped kiai.
Timing	Inconsistent or unset preview time.
Timing	Unsnapped hit objects.
Timing	Unused timing lines.
Timing	Wrongly or inconsistently snapped hit objects.
Spread	Lowest difficulty too difficult for the given drain/play time(s).
Settings	Abnormal difficulty settings.
Settings	Inconsistent mapset id, countdown, epilepsy warning, etc.
Settings	Slider tick rates not aligning with any common beat snap divisor.
Settings	Abnormal difficulty settings.
Hit Sounds	Low volume hit sounding.
Events	Breaks only achievable through .osu editing.
Compose	Abnormal amount of slider nodes.
Compose	Concurrent hit objects.
Compose	Too short drain time.
Compose	Invisible sliders.
Compose	Abnormal amount of slider nodes.

Standard

Category	Issue Message
Timing	Hit object is unaffected by a line very close to it.
Spread	Multiple reverses on too short sliders.
Spread	Too short sliders.
Spread	Object too close or far away from previous.
Spread	Too short spinner time or spinner recovery time.
Spread	Perfect stacks too close in time.
Spread	Objects close in time not overlapping.
Settings	Default combo colours without forced skin.
Settings	Too dark or bright combo colours or slider borders.
Hit Sounds	Long periods without hit sounding.
Events	Storyboarded hit sounds.
Compose	Burai slider.
Compose	Too short spinner.
Compose	Obscured reverse arrows.
Compose	Offscreen hit objects.
Compose	Abnormally large spacing.
Compose	Ambiguous slider intersection.

Taiko

Category	Issue Message
Timing	Inconsistent omitted bar lines.
Timing	Hit object is unaffected by a line very close to it.
Events	Storyboarded hit sounds.

Catch

Category	Issue Message
Timing	Hit object is unaffected by a line very close to it.
Settings	Default combo colours without forced skin.
Settings	Too dark or bright combo colours or slider borders.
Hit Sounds	Long periods without hit sounding.
Events	Storyboarded hit sounds.
Compose	Spinner gap too small.

Modes apart from standard do not have their SRs implemented, so difficulty levels will likely be wrong.

Reporting Bugs

Either post an issue here or contact me on Discord @naxess. Give beatmapset and reproduction steps if applicable. If you don't have me on discord just join the Aiess Project, after which you should be able to message me.