Replay Tools

Playing an existing recording as if it were arriving live.

A replay session is the same object as a live stream — every acquisition, DSP, event, visualization, and stimulation tool works on it identically. Only the tools on this page require a replay.

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inspect_recording

Open a file and describe it without starting playback.

Arg	Default	Meaning
path	—	Absolute, or relative to EEG_MCP_RECORDINGS_DIR
board	None	Required for BrainFlow CSV, which has no layout header
max_events	100	Cap on listed events

Returns: sfreq, n_channels, ch_names, duration_sec, n_events_in_file, format, and the events list with onsets in seconds.

Use it to check event labels before building a pipeline that keys on them.

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start_replay

Play a recording against a wall clock, re-emitting its annotations as events.

Arg	Default	Meaning
session_id	—	Handle for later calls
path	—	Absolute or relative to the recordings dir
speed	1.0	Playback rate; 1.0 is true recording rate
loop	false	Restart at the end, emitting replay_loop
start_sec	0.0	Offset to begin from
board	None	Required for BrainFlow CSV
picks	None	MNE channel selection, e.g. "eeg"
use_stim_channel	true	Also extract events from a trigger channel

Timestamps are real Unix time, not file time, so replayed events and dispatched stimulations share one comparable clock.

Speed changes what you are testing

Above 1.0 you are testing logic, not latency — chunks arrive larger and less often. Always do a final pass at speed=1.0.

Supported formats

EDF, BDF, GDF, SET, FIF, BrainVision, and anything else MNE reads, plus BrainFlow CSV. See the format table.

start_replay vs PLAYBACK_FILE_BOARD

	start_replay	PLAYBACK_FILE_BOARD
Formats	Everything MNE reads + BrainFlow CSV	BrainFlow CSV only
Speed control	Yes	No
Seek / pause	Yes	No
Looping	Yes	Yes (loopback_true)
Pacing	This server's media clock	BrainFlow's own

Use the playback board when you specifically want BrainFlow's pacing; otherwise start_replay.

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replay_control

Pause, resume, seek, or change speed.

Arg	Meaning
action	pause, resume, seek, speed, status
position_sec	Required for seek
speed	Required for speed

replay_control(session_id="r1", action="pause")
replay_control(session_id="r1", action="seek", position_sec=310)
replay_control(session_id="r1", action="speed", speed=8.0)

Returns: replay with position_sec, duration_sec, progress, speed, loops_completed, paused, exhausted.

Seek clears the buffers

Both ring buffers are cleared and filter state is reset, so you never get a window that silently straddles the discontinuity. Absolute sample indices stay monotonic, so events from before the jump correctly read as having scrolled out rather than pointing at unrelated samples.

Calling this on a live session raises — playback controls apply only to replays.

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list_recording_events

Every event in the source file, including ones not yet reached.

Two different lists

list_recording_events — the complete list from the file. Use it to plan.

get_events — what has actually been emitted so far. Use it to verify.