EEG File Import

One node reads every EEG recording Grafit meets, by its bytes rather than by its name: a tab- or comma-separated text table with a .info sidecar beside it (a .easy recording), Grafit's own session folders (recording.grafitraw with header.json, and the recording.csv / recording.edf exports), and the European Data Format — EDF, EDF+ with its annotations, and 24-bit BDF. The inspector reports what it found ("EDF+ · 19 channels · 256 Hz · 12:34"). A 107 MB, 32-channel, 500 Hz text recording decodes in under half a second.

It plugs in where a live device does. MTL Data is the same dictionary the device node publishes, so EEG Plot, FFT EEG, Signal Window and Impedance take it unchanged, and MTL Data A…D repeat it in groups of eight channels for patches built around an eight-channel amplifier. It also publishes a Data Lab Signal, so Plot, Signal Window and every Analyze node take it with no bridge in between. The dictionary states its own microvolt scale, so a file shows true microvolts rather than raw converter counts.

The file feeds a rolling ring buffer in real time, exactly as a device would, and the ring's write head never rewinds — a seek, a loop wrap or a scrub only changes which frames come next, so every consumer downstream sees one continuous stream and never has to handle time going backwards.

Files stay where they are: the node keeps a path and a security bookmark, never the bytes, so a project stays small and a recording is never duplicated.

File (string) — the recording. Drop an .easy, .edf, .bdf or .grafitraw file on the graph and the node appears already holding it; drop a session folder and it reads the raw file inside with header.json for names. Cable a Library node's Path here (Kind: EEG Recordings) to step through a folder of recordings.

Play (bool, default true), Speed (float, default 1.0) — the transport. Negative Speed plays backwards.

Time Mode (int, default Transport) — Transport runs on the node's own clock, Scrub hands position to the Scrub input (0…1 of the in/out range), Trigger plays from the start on each rising edge.

Loop Mode (int, default Loop) — Loop · Once — Stop · Ping-Pong. In Point and Out Point (0…1) cut the region that plays, and Restart is a rising-edge jump back to the in point.

Sample Rate (float, default 0 = automatic) — the rate is taken from the sidecar or the header first, then from a timestamp column, and failing that 250 Hz with a warning; any non-zero value here overrides all of it.

Remove DC (bool, default true) — raw electrodes sit at tens of millivolts, which would dwarf the signal on every plot. This subtracts each channel's whole-file mean: no filter, no phase shift, and it says so in Info.

Window (float, default 10) — seconds of history the ring holds, which is what EEG Plot and the spectral nodes see.

Marker Hold (float, default 0) — how long the Marker code stays up after an event, in seconds. Marker Pulse is always a single frame regardless.

Channels are yours: the Settings tab holds a table to include, rename and order them — Anatomical puts Fp, F, C, P, T, O front to back, As in file restores the recording's own order — and the outputs follow. The same tab holds Gain and Vref for the microvolt scale, and a Fill gaps switch for recordings with dropped frames.

Markers are first-class. A trigger column, EDF+ annotations (distinct texts numbered in order of first appearance) and sample-counter gaps in Grafit's own files all become one stream: Marker is the current code (0 = none), Marker Pulse fires for exactly one frame at each event, and Markers carries the whole list for a timeline or a plot overlay. Cable Marker Pulse into a Do Once, a Counter or a Timer and the recording drives the patch.

Gaps are reported, not hidden. A sample counter that skips or a timestamp that jumps is counted as lost frames and marked in the marker stream. Settings' Fill gaps holds the previous frame across each gap so the time axis stays honest; with it off (the default) the gap is simply skipped, as the recorder skipped it.

Decoding stops at 2 GB of samples — roughly four and a half hours of 64 channels at 500 Hz — with a warning naming how much was read.

• EEG from file: EEG File Import → EEG Plot → Canvas — the recording scrolls exactly as a live device would, transport and all.
• File spectrum: EEG File Import (MTL Data) → FFT EEG → EEG Spectrum → Canvas, for band powers in real microvolts squared.
• Into the Data Lab: EEG File Import (Signal) → Signal Window → Plot 2D, or straight into the Analyze nodes for statistics, filters and correlations.
• Event-locked visuals: Marker Pulse → Counter → Switch to change scene on every annotation in an EDF+ file.
• A folder of sessions: Library (Kind: EEG Recordings) → Path → the node's File, with Next / Previous stepping through subjects.
• Scrub for review: Time Mode Scrub with a fader or the Timeline into Scrub — drag through an hour of recording while the plot and the spectrum follow.

A recording has no electrodes to measure, so the Impedance node says so plainly rather than showing a meaningless number.