Signal Flow Planner

What it is for #

A signal flow diagram answers the question you get asked on every job: what is plugged into what? This planner draws one the way the gear actually looks from the back. Each device is a block with its inputs down the left side and its outputs down the right, so signal reads from left to right across the page, like a block diagram. A cable runs from a specific output to a specific input, like it does in the rack.

It opens on an example rig. Three cameras and two DeckLink playout channels feed an ATEM 2 M/E Constellation HD. One camera has only HDMI, so it goes through a Micro Converter first. The Constellation feeds a HyperDeck and an ATEM Mini Pro ISO, which drives a multiview monitor. The Mini's inputs are HDMI, so there is a second converter on the way in.

How to use it #

Add devices. Drag one in from the library on the left, or click it to drop it in the middle of the view.
Name them. Select a device and give it a label, like CAM 1 or PLAYOUT. The label becomes the device's headline and is what every message calls it.
Cable them. Drag from an output to an input. While you drag, the ports you can drop on light up: green where the connector types match, amber where they don't.
Tidy up. Drag devices around and the cables re-route themselves. Click a cable to show dots on its runs, and drag a dot to move that run. Double-click the cable to hand it back to the router.
Group it. + Zone draws a labelled, coloured area (Sources, Record, Stream). With things selected, it draws the zone around them. Drag a zone by its name tab and everything inside comes along. + Note adds a note (white, or a colour you pick in its panel) and + Text a heading.
Read the warnings. With nothing selected, the panel on the right lists everything that looks wrong. Click a warning to jump to its cable.

Selecting, moving and undoing #

Drag across empty space to select everything the box touches; Shift-click adds or removes one thing. A box drawn inside a zone picks the gear, not the zone.
Drag any selected thing to move the whole selection. Positions snap to the grid, and a device you drag snaps level with a port it is cabled to, so the cable runs straight; hold Alt while dragging to place freely. The arrow keys nudge by one grid step (Shift + arrow: one pixel).
With several things selected, the panel on the right lines them up (left, centre, right, top, middle, bottom) or spaces them evenly. It can also wrap them in a zone or duplicate them.
Double-click a device, note or zone to name it or write in it.
To pan, scroll, hold Space and drag, or drag with the middle button. On a touch screen, one finger pans and two pinch to zoom.
⌘/Ctrl + Z undoes and ⌘/Ctrl + Shift + Z redoes, back through the last hundred changes, including New, Example and Import. ⌘/Ctrl + C / X / V copy, cut and paste through the clipboard, so a selection can go into a plan in another tab; cables between copied devices come along. ⌘/Ctrl + D duplicates and ⌘/Ctrl + A selects everything.

Your plan is saved in this browser as you work. Nothing is uploaded anywhere. Use Export → Plan file to download the plan, and Import… (or drop the file on the editor) to open it again, in this browser or another.

Your own devices #

If the gear you use isn't in the library, build it. + New device opens the builder: a name, a manufacturer, a category, colours, and the two sides of ports. Each port has a name, a connector type and a direction. Ports on the left side are inputs and ports on the right side are outputs; In/Out ports (Ethernet, USB, talkback) can sit on either side. Drag a port's grip, or press Alt + ↑ / ↓ on it, to change its place down the side. + Several… adds a numbered run in one go, like SDI 1 to SDI 20. The preview above the form shows exactly what will be placed.

To change a built-in device, copy it into My devices with its ⧉ button and edit the copy. To change one device in the plan only, like renaming the ports of the switcher you're actually using, select it and choose Edit device…. Save to My devices keeps a copy of a placed device for next time.

A placed device is a copy of its template. Editing a device in My devices never changes plans that already use it, so an old plan always shows the gear as it was drawn.

Export at the top of the library downloads My devices as one file. Import it in another browser, or hand it to a colleague. Importing a device file again replaces the devices it already added, so an updated file can be imported over an old one.

The rules it follows #

An input takes one cable. That is how sockets work. To move a cable, drag its input end somewhere else.
An output may feed several cables, with a warning. Splitting an SDI or HDMI signal needs a distribution amp or a loop-out. The plan lets you draw it, but tells you.
A cable between different connector types is drawn red and dashed. HDMI into SDI won't work without a converter. You can still draw it, since a diagram may be showing a mistake on purpose.
Ethernet, USB and other two-way ports can be either end of a cable, and they take one cable each.
Switchable connectors, like the four on a DeckLink Duo 2, can be set to input or output on the placed device. Select the device and use Make output / Make input next to the port.

The built-in library #

The Blackmagic devices follow the connection lists on Blackmagic's own tech specs pages, trimmed to what gets cabled. Power inlets, media slots and internal connections are left out. A few details to know:

The ATEM Constellation HD models have no dedicated multiview outputs: any SDI output can carry a multiview, so they are all plain OUT ports.
DeckLink connectors that Desktop Video Setup can switch are switchable here too. Their starting direction is a common split.
Gear whose connections couldn't be confirmed from Blackmagic's specs is left out rather than guessed. The generic blocks, or your own devices, cover the rest.

Showing only some connector types #

A full rig drawing carries reference, timecode, RS-422 and network runs that get in the way when you only want to talk about video. View lists every connector type in the plan with how many cables use it. Untick a type to hide it, or choose Video only to keep SDI, HDMI, fiber and DisplayPort. Hidden types leave the drawing completely: their cables go, and so do their ports, so devices shrink to what is shown.

The filter is saved with the plan, and exports draw exactly what you see. A filtered drawing says so in its title block (Showing SDI, HDMI only) and its legend lists only the shown types, so it can't be mistaken for the whole rig. On screen, a note in the corner of the canvas says the same, with a Show all button. Hidden ports can't be cabled until you show them again.

The filter only changes what is drawn. Every cable, port and warning is still in the plan, and the Cable list still lists every cable. Tick Only shown types there to list, download or print just the shown ones.

View → Design switches how devices look. New draws devices as white boxes with a heavy frame and a hard shadow over a line grid; to colour one, tick Colour the body in its Edit device… window (or in the builder for your own devices). Classic draws each device in its built-in colours with coloured edge bars over a dot grid. Each device keeps its colours for both designs, and exports use the design you pick.

To give the drawing more room, Library and Details at the ends of the toolbar fold the side panels away, as do the [ and ] keys. The browser remembers your choice.

Naming a switcher's ports from its ATEM config #

A plan reads better when the switcher's inputs say CAM 1 WIDE and PLAYOUT A rather than IN 1 and IN 4, and those names already exist in the switcher. In ATEM Software Control, save the switcher's configuration (File → Save As). Then select the switcher in the plan, choose Name ports from ATEM config… and pick the file. You can also drop the file on the editor, or open it with Import….

A window lists every port the file would rename: the current name, what the ATEM calls that connector, and the new name. Inputs are matched in order (input 1 to the first video input, and so on), and the SDI outputs the same way. Choose long names, short names (CAM1), or long names with the input number in front. Untick any port you want to keep as it is. Outputs still on the ATEM's factory names (Out 3) start unticked, since they add nothing. If the file names more inputs than the device in the plan has, the window says so. That usually means the plan has a different model than the switcher the file came from.

Only video ports are renamed, never reference, audio or talkback. Port ids stay the same, so every cable stays connected, and undo puts the old names back. The file has to be a full configuration: a macro-only or audio-only export has no input names in it, and the tool will say so.

The cable list #

Every cable gets a number when you draw it, counted per connector type: SDI-001, SDI-002, HDMI-001. The number shows on the cable just before the input it plugs into. The # button hides the numbers, on the canvas and in exports. A cable keeps its number when other cables come and go, and when you move its end to another input, so you can write it on the physical cable and trust it.

Cable list opens every cable in a table: its number, both ends, a length in metres and a note. Lengths and notes apply as you type, and the footer totals each type ("SDI 7 cables, 27.5 m"). Clicking a number takes you to that cable on the canvas. You can also edit a selected cable's number, length and note in the panel on the right.

Renumber numbers each type from 1 again, left to right across the drawing, for a tidy list before the labels go on. Undo puts the old numbers back. Two cables with the same number show up as a warning.
Download CSV gives a spreadsheet of the list. Excel in Denmark, Germany and other countries that write decimals with a comma expects a semicolon between columns, so the separator follows your computer's language. You can change it in the window. Letters like æ, ø and å come through intact.
Print prints the list on A4 with the plan's title, venue, date, revision and author at the top, and the column headings repeated on every page.

Exporting and printing #

With nothing selected, the panel on the right holds the plan's title block: title, venue, date, revision and who drew it. Leave the date empty and the day of export is used. The Export menu turns the plan into:

Image (.svg): the whole drawing on a white sheet, with a frame, a legend of the connector types the cables use, and the title block in the corner. It opens in any browser, and in Inkscape or Illustrator for further work.
Image (.png): the same sheet at twice its size, for slides, chat and documents.
Print or PDF (A4 / A3): the sheet scaled to one landscape page. Choose Save as PDF in the print dialog for a PDF. The paper size is a suggestion; some browsers let the dialog decide.
Cable list (.csv): the cable list as a spreadsheet, the same as Download CSV in the Cable list window.
draw.io (.drawio): a file to keep editing at app.diagrams.net or in the draw.io app. Devices come across as groups with one cell per port, and every cable is attached to its two ports, so cables follow when you move things there. The routes come along as waypoints, so the drawing looks the same when it opens.

The exports are always drawn black on white, whichever theme the editor is in. Untick Title block and legend at the top of the menu for just the drawing.

Export → Embed link… makes a link to a read-only copy of the drawing. Whoever opens it can pan and zoom, but nothing can be moved or changed. It shows the design you are using and the connector types you are showing, so a link from an SDI and HDMI only view shows only those cables. In the window you choose a light or dark theme (or one that follows the viewer's system) and whether the plan's title shows in the corner.

To put the drawing on a Notion page, type /embed, paste the link and choose Embed link. The drawing fits itself to the embed's frame. Drag the corners of the embed to give it more room. The same link works in any tool that embeds web pages, and as a plain link in a message.

What to know about these links:

The plan travels inside the link. It is compressed into the part after the #, which browsers never send to the server. Nothing is uploaded or stored anywhere, and there is no account.
Anyone with the link can see the drawing, including the device labels, notes and title block. Share it like you would share the PDF.
A link is a snapshot. Changes made after you copy it are not in it. Copy a new link and replace the embed when the plan changes.
Open in editor in the viewer opens the plan here, where it can be changed. It asks before it replaces the plan you have open, and Undo brings yours back.
A large plan makes a long link, a few thousand characters for the example rig. Should an app ever cut one short, the viewer says the link is damaged. Share the plan file instead.