SkuldTurn 1.0 manual

What SkuldTurn does

A printed part often turns in the middle of a busy passage. SkuldTurn moves whole systems (full-width horizontal bands of music) between pages so that every physical page turn falls after a system you marked as a place where you can turn. The notation is never redrawn. Each band is copied from your PDF as clipped vector content, at one uniform scale between 70% and 100%.

You decide where turns are possible. A turn point means only that you marked it. SkuldTurn does not read or judge the music, and it does not detect rests.

What you need

A desktop computer with Google Chrome. Version 1.0 was tested with Google Chrome 152 on Linux. Other browsers and systems were not tested.
One PDF of music you are allowed to copy, for example your own purchased or public-domain part. Scans are fine if they are inside a PDF.
No installation, account or internet connection. Unzip the folder and open app/index.html in Chrome (double-click it, or drag it onto a Chrome window).

First result in three minutes (example score)

SkuldTurn start screen with Open a PDF and Load the example score buttons — Start screen. Click **Load the example score**.

The example turn-study-1.pdf is an original 3-page practice score with 15 numbered systems (S01–S15) and a copyright notice on page 1. Its project already marks turn points after S04, S09, S12 and S15.

Step 1: Review regions

Step 1: source page with coloured bands for the header, music systems and notice — Blue bands are music systems, the dashed grey band is left out (the running header), and green is the notice repeated in the footer.

On each page, check the bands, then tick I reviewed this page. Export stays locked until every page is reviewed. Red shading marks ink that is outside every band. A yellow note warns when a left-out band contains ink.

Step 2: Mark turn points

Step 2: list of systems with turn-point checkboxes — Tick each system after which you have a hand free. The last system always counts as an end.

Step 3: Preview & export

Step 3: preview of four single output pages with turns after S04, S09 and S12 — Single pages at 100% on US Letter with 36 pt margins: pages [S01–S04] [S05–S09] [S10–S12] [S13–S15]. Every turn is at a marked point.

Expected example results (US Letter, margins 36 pt, binding 0, notice repeated):

Layout	Output pages (systems)	Physical turns after
Single pages, 100%	[S01–S04] [S05–S09] [S10–S12] [S13–S15]	S04, S09, S12
Single pages, 80%	[S01–S04] [S05–S09] [S10–S15]	S04, S09
Binder, first page on the left	[S01–S05][S06–S09] \| [S10–S12][S13–S15]	S09
Binder, first page on the right	[S01–S04] \| [S05–S08][S09–S12] \| [S13–S15]	S04, S12

Step 3: binder spreads, first page on the left — Binder spreads with the first page on the left: two open spreads and one turn after S09.

Your own PDF

Click Open PDF (or drop the file on the start screen). SkuldTurn checks the file before it changes anything. If the file is refused, the current project stays as it was.
SkuldTurn proposes bands by finding staff lines. A proposal is only a starting point: it can cut lyrics, titles or dynamics into the wrong band. Check every page.
Fix bands: drag on an empty part of the page to add a band; drag a band edge to move it; use Split, Merge with next, Delete, Undo and Redo. Type exact Top/Bottom values in points, or set the Kind:
- Music system: moves as one unit.
- Title: placed above the first music system and fitted with it.
- Notice: one band, such as a copyright line, repeated at the foot of every output page.
- Leave out: not shown on the printed pages (for example running headers or old page numbers). It is hidden, not deleted: see Privacy.
Check the side trim. Each band keeps the full width between the left and right trim of its page. A warning appears if ink falls outside the trim.
Keyboard: click the page, then press J/K to select the next or previous band, E to switch between top and bottom edge, ↑/↓ to move that edge by 1 pt (Shift for 10 pt), T to toggle a turn point, Delete to remove the band, and Ctrl+Z/Ctrl+Y to undo or redo.

You are responsible for the bands you approve. If a band boundary cuts through notes or lyrics, the export copies exactly that cut. Look at the preview before printing.

Supported files and limits

Item	Supported in 1.0
Input	One PDF of up to 32 MiB (33,554,432 bytes) and 20 pages. Every page must be 216–1296 pt (3–18 inches) on each side and upright (no /Rotate). A MediaBox that does not start at 0,0 is handled (tested); files with a CropBox smaller than the MediaBox open, but that case was not separately tested in 1.0.
Refused (with a message)	Encrypted or permission-restricted PDFs (never bypassed), signature fields, form fields, XFA, JavaScript or document actions, optional-content layers, comment/stamp/widget annotations, rotated pages, damaged files and non-PDF files. Link annotations are allowed but not carried over.
Regions	Up to 120 bands per project, each at least 6 pt tall, with no overlaps. One title band and one notice band.
Output	PDF on US Letter (612 × 792 pt) or A4 (595.28 × 841.89 pt), portrait. Uniform scale 70–100%. Margins 0–144 pt, binding allowance 0–72 pt on the inner edge. Fixed 10 pt gap between bands. Small page labels (“2 / 4”) in the bottom margin when it is at least 16 pt.
Also exported	Turn plan as TXT and JSON (output page, system IDs, source page and bounds, scale, turn points) and an editable project file (`.skuldturn.json`, at most 1 MiB).

Reviewing the result

The preview shows output pages the way you will see them: one page per view in single mode, two pages per open spread in binder modes, with a green TURN bar between views. The summary states the number of output pages, intentionally blank pages and physical turns.

The planner prefers, in order: the fewest output pages, then the fewest physical turns, then the lowest fill of the fullest page (measured to 0.01 pt, as in the turn plan), then earlier breaks: when several layouts are equal on all of these, the one whose first turn comes earliest wins, then the earliest second turn, and so on. It compares whole layouts rather than deciding page by page. Inside a spread it balances the two pages, keeping more systems on the first page when that is equally even. In binder modes an empty page between spreads is kept (and labelled “Intentionally blank”) so the following spreads stay in order; an unused final page is left out.

Infeasible layout message naming S01 to S12 — If your turn points cannot work, SkuldTurn names the stretch (here S01–S12 with only S12 and S15 marked) and suggests a turn point inside the stretch or another layout that fits. Nothing is inserted silently.

Export, print and reopen

Download PDF saves <name>-skuldturn.pdf. Your original PDF is never modified. Chrome keeps earlier downloads (it adds “(1)” to repeated names).
Download turn plan (TXT or JSON) records which system went to which output page.
Save project stores bands, turn points and settings with the SHA-256 fingerprint of your PDF. To reopen, click Open project, then open the same PDF. A different or edited PDF is refused, even with the same name.
Print at actual size / 100%. Turn off “fit to page”. Measure the first page with a ruler: with 36 pt margins, the music starts 0.5 inch from the top edge.

Which way round?

Binder, first page on the right

turn

Binder, first page on the left

turn

“First page on the right” is how a ring binder normally opens: page 1 is on the right, then each turn shows an even page on the left and an odd page on the right. Use “first page on the left” when pages 1 and 2 lie side by side, for example two loose sheets on the stand. SkuldTurn makes no claims about your printer’s duplex settings: print one test sheet first.

Troubleshooting

Message or problem	What to do
“encrypted or has permission restrictions”	SkuldTurn does not remove protection. Use an unprotected copy you are allowed to edit.
“annotation … would be lost”, “form fields”, “optional content”	Flatten the PDF first (for example print it to a new PDF), then open the new file.
“rotated by 90°”	Save an upright copy of the PDF first.
“has no marked turn point that fits”	Mark a real turn point inside the named stretch, reduce the scale or margins, or try a binder layout. The suggestions only change settings when you click them.
“taller than the music area”	One band is too tall for a page: split it at a staff gap or lower the scale.
“wide … printable width”	Narrow the side trim, reduce side margins or binding, or lower the scale.
Export buttons are greyed out	The summary lists what is missing, usually a page that is not yet reviewed.
“does not match the project”	SkuldTurn compares fingerprints, not names. The project file is set aside after this message, so other PDFs open normally again. To use the project, click Open project again and then open the exact PDF it was saved with.

Privacy

SkuldTurn runs entirely inside the Chrome tab. It makes no network requests, collects no statistics and needs no account. Files leave the tab only when you click a download button. Closing the tab discards the work you did not save.

Hidden is not removed. The exported PDF contains each source page, clipped to show only your bands. Left-out bands, trimmed sides and unassigned areas are invisible on paper, but they are still inside the PDF file: their text can be found, copied or extracted with other PDF tools. Do not use SkuldTurn to remove names, notes or other private content before sharing a file.

Uninstall

Delete the unzipped SkuldTurn folder. Nothing else is installed. Downloaded PDFs, plans and projects stay in your downloads folder until you delete them.

Exact limitations

Tested in Google Chrome 152 on Linux only. Windows, macOS, other browsers, tablets and phones are untested. The interface adapts to narrow windows, but editing bands is meant for a desktop.
Bands are full-width horizontal strips. Music cannot be rearranged inside a band, and repeats or D.S./coda jumps are not interpreted: source order is kept.
Automatic band proposals use staff-line detection and can be wrong, especially on skewed or noisy scans and multi-staff systems. For example, a lyric line or marking just under a running header can be proposed as part of the left-out header band. Manual review is required: you are responsible for the bands you approve, and the warnings about ink in left-out or unassigned areas are there to help you check.
Left-out and trimmed areas are hidden, not deleted; this is not redaction.
Interactive PDF content (links, bookmarks, form fields, comments, tags, layers) is not carried over; files that would lose visible content are refused.
No OMR, transposition, audio, cloud storage, copyright advice or DRM removal. Use only music you are allowed to copy, and keep its notices.