audace-display 0.2.0

Visualization of Audace DAS acquisition files (.dat / .hdf5 / .tdms / .sgy).

audace-display

Visualization of Audace DAS acquisition files -- simple, fast, safe.

audace-display reads any format produced by the Filewriter (.dat, .hdf5, .tdms, .sgy) via the invisensing library, automatically detects the file mode, and shows:

• a heatmap (time x distance waterfall) for demodulated files,
• an animated oscilloscope (lines replayed in real time, looping) for raw files.

Reading is streamed and decimated: a multi-GB file is reduced to screen resolution without ever being fully loaded into memory.

Installation

pip install audace-display              # matplotlib (static + interactive + PNG)
pip install audace-display[interactive] # + pyqtgraph backend (fast interactive)

Dependencies: numpy, matplotlib, invisensing (>= 1.1.0 recommended for the O(1) seek and TDMS/SEG-Y streaming; works from 1.0.0). Optional interactive extra: pyqtgraph + PyQt5.

Quick start

# Auto: heatmap if demodulated, oscilloscope if raw -- zero options
audace-display acquisition.dat

# PNG export (server / headless mode, no X11/Wayland)
audace-display acquisition.dat --save output.png

That's all for everyday use. The rest is fine-grained control.

Display (backends)

Mode	Command	For
interactive matplotlib	(default)	quick look, publication quality
headless PNG	--save out.png	server without X11/Wayland, batch scripts
interactive pyqtgraph	--backend pyqtgraph	smooth exploration (GPU pan/zoom) on large files

matplotlib stays the default (simple, no heavy dependency). For smooth pan/zoom on long acquisitions, --backend pyqtgraph is far more responsive (GPU re-render + on-the-fly downsampling) -- install the extra pip install audace-display[interactive]. --save always renders the PNG via matplotlib, regardless of --backend.

audace-display heatmap acq.dat --backend pyqtgraph   # fast viewer
audace-display acq.dat --backend pyqtgraph           # same, in auto mode
audace-display acq.dat --save out.png                # headless PNG

Raw mode: real-time oscilloscope

For a raw file, the default is an animated oscilloscope: each frame draws the current line (pulse) -- amplitude vs distance along the fiber -- and the cursor advances at trigger_frequency lines/second (real time), looping. At high rates, lines are skipped to stay real-time (the pace stays exact, locked to the clock). Optimized: O(1) per-line seek (invisensing >= 1.1.0), "peak" decimation of large lines, reused curve, frozen axes. For maximum smoothness, --backend pyqtgraph.

audace-display scope acq.dat                  # real time, looping
audace-display scope acq.dat --speed 0.25     # 4x slow motion
audace-display scope acq.dat --fps 60 --backend pyqtgraph
audace-display scope acq.dat --start-time 1.0 --duration 0.5   # loop over 0.5 s
audace-display scope acq.dat --line 1000 --save frame.png      # 1 frozen line (PNG)

Option	Effect
--speed F	Playback speed (1.0 = real time = trig_frequency lines/s)
--fps N	Render frames/s (default 30)
--line N	Frozen line exported with --save (default 0)
--max-points N	Max points drawn per line (peak decimation). Default 4000

Requires invisensing >= 1.1.0 (O(1) per-line seek).

Subcommands

Command	Role
(none)	Auto: heatmap (demodulated) or animated oscilloscope (raw)
info	Header metadata + stats of the default channel
heatmap	Time x distance waterfall, color = channel
scope	Oscilloscope: replays the lines (pulses) in real time, looping
fft	Temporal spectrum (FFT along the pulses) at 1+ position(s)
trace	1-D time trace at one position
inspect	One location: time waveform + FFT spectrum in a single figure
demod	Demodulate via an external script, then show as heatmap

audace-display info acquisition.dat
audace-display heatmap acquisition.dat --channel magnitude --db
audace-display heatmap acquisition.dat --start-time 0.5 --duration 1.0
audace-display heatmap acquisition.dat --start-distance 50 --end-distance 200
audace-display fft   acquisition.dat --position 120
audace-display fft   acquisition.dat --position 50,100,150 --db
audace-display fft   acquisition.dat --position-range 100:200 --window blackman
audace-display trace acquisition.dat --position 100
audace-display inspect acquisition.dat --index 120
audace-display inspect acquisition.dat --position 60 --fft-log --fmax 200

Channels per mode

File mode	Valid channels	Default
raw	raw	raw
iq	i, q, magnitude (|IQ|), phase_wrapped	magnitude
arctan_magnitude	arctan, magnitude (sqrt(I^2+Q^2))	magnitude
phase	phase	phase

Common aliases: mag/amp -> magnitude, atan -> arctan, angle -> phase_wrapped. No demodulation is applied: channels are read as the Filewriter wrote them.

Large files (200 MB - 10 GB)

The heatmap is computed in a single streaming pass: pulses are read in chunks and aggregated on the fly into a --max-time-bins x --max-space-bins grid (2000 x 2000 by default). RAM does not depend on file size. Line plots use a min/max-preserving decimation (no visual aliasing).

Option	Effect
--max-time-bins N	Temporal (X) resolution of the waterfall. Default 2000
--max-space-bins N	Spatial (Y) resolution of the waterfall. Default 2000
--reduce {mean,rms,std,peak}	Temporal aggregation statistic. Default mean
--max-pulses N	Bound the number of pulses read (default: whole file)
--subsample-time N	(fft/trace) keep only one pulse out of N

.dat and .hdf5 stream natively; .tdms and .sgy also stream with invisensing >= 1.1.0. --start-time seeks directly (O(1) seek) with 1.1.0.

Demodulation via external plugin

audace-display contains no demodulation code: it defines an API contract and loads a Python script that you provide (never published). The result is displayed as a heatmap. This keeps the published package generic and safe — your (often proprietary) signal-processing recipe never leaves your machine.

Your script defines either a stateless demodulate function or a stateful Demodulator class. Both turn a raw pulse chunk (rows, line_size) into a (rows, positions) field:

# my_demod.py  --  stateless function (memoryless transforms)
import numpy as np

OUTPUT_LABEL = "magnitude (V)"   # colorbar label (optional)
IS_ANGULAR   = False             # diverging colormap centered on 0 (optional)

def demodulate(chunk, *, sample_rate, trig_frequency, line_size, meta):
    # interleaved I/Q raw -> |IQ|
    i = chunk[:, 0::2].astype(np.float32)
    q = chunk[:, 1::2].astype(np.float32)
    return np.sqrt(i * i + q * q)

# my_demod.py  --  stateful class (filters with temporal memory)
class Demodulator:
    OUTPUT_LABEL = "phase (rad)"
    IS_ANGULAR   = True

    def __init__(self, *, sample_rate, trig_frequency, line_size, meta):
        ...                        # build filters / allocate state

    def process(self, chunk):      # called on contiguous time chunks, in order
        # chunk: (rows, line_size) raw -> (rows, positions) float32
        ...

audace-display demod raw.dat --script my_demod.py --save demod.png
audace-display demod raw.dat --script my_demod.py --db --start-distance 50 --end-distance 200

The contract in short:

• Input chunk: the buffer from invisensing.File.read_lines, shape (rows, line_size), in the file's native dtype (int16/int32/float32). For interleaved I/Q, chunk[:, 0::2] is I and chunk[:, 1::2] is Q. Cast to float before arithmetic — integer dtypes overflow silently.
• kwargs (keyword-only, all optional — declare only what you use): sample_rate (intra-pulse Hz), trig_frequency (pulse rate Hz), line_size, and meta (full header dict: positions_per_line, range_v, flags, mode, num_lines, …).
• Output: a 2-D (rows, positions) array — rows must match the input (don't resample time), positions constant across chunks. Cast to float32 for display.
• Streaming guarantees: chunks arrive in time order, contiguous, same positions → a stateful filter (IIR, running mean, phase unwrap) is safe in the class form (state on self). The function form sees each chunk independently (state resets per chunk) — use it only for memoryless math.

📖 Full guide with worked examples (I/Q magnitude, instantaneous phase, stateful IIR low-pass), the complete meta reference, the pipeline diagram, how to test a plugin, and FAQ: docs/DEMOD_PLUGIN.md.

Programmatic API

from invisensing import File
from audace_display import load_decimated, resolve_channel

with File("acquisition.dat") as f:
    _, resolver, label, is_angular = resolve_channel(None, f.mode)
    res = load_decimated(f, lambda raw: resolver(f, raw),
                         max_time_bins=1000, max_space_bins=1000)
    # res.data: (n_time, n_space) float32 ; res.t_extent, res.d_extent

Default behavior

• Interactive display by default; --save out.png for headless mode (the Agg backend is chosen automatically when there is no display).
• Auto colormap: viridis (sequential) for magnitude/raw, RdBu_r (diverging, centered on 0) for phase/arctan. Override with --cmap.
• Auto-scaling: 1/99 percentiles in linear, median - 30 dB -> max in dB, centered on 0 for angular channels. Override with --vmin/--vmax.

License

MIT.