Compatibility
Python wheels cover CPython 3.10+ on manylinux x86-64, Windows AMD64, macOS Intel, and
macOS Apple Silicon; musllinux is not provided. Node.js >=18 is required. Chromium
is acceptance-tested. Other evergreen browsers are designed for but unverified.
AudioWorklet support requires HTTPS or localhost; direct file: loading is unsupported.
The npm package is ESM-only; use .mjs or a consumer package with
"type": "module". CommonJS require() is unsupported.
Graph v1 is supported on the JavaScript and Python bindings only; see Graph v1 supported surfaces.
The core does not decode, encode, resample, call ffmpeg, host VST/AU, or expose public integrated-LUFS/true-peak measurement.
Analyzers and telemetry
LevelMeter, NoteSpectrogram, Oscilloscope, SpectrumAnalyzer,
Spectrogram, and StereoMeter expose decoded semantic observations in Python, JavaScript offline and
streaming processing, and AudioWorklet. Telemetry is opt-in: the first callback or
subscriber enables it and the last unsubscribe disables it. Long renders drain after
every processing block. Public frames identify the semantic effect and contain owned
arrays; binary frame types, versions, tap IDs, payload bytes, and Worklet transport stay
private. Unknown or malformed frames are discarded.
Common metadata:
| JavaScript / Python | Meaning |
|---|---|
kind / kind |
level, noteSpectrogram, oscilloscope, spectrum, spectrogram, or stereo |
effectType / effect_type |
Semantic effect type |
effectId / effect_id |
Declared effect ID, or null / None |
effectIndex / effect_index |
Zero-based position in the declared DSP chain |
sequence / sequence |
Per-tap telemetry sequence number |
dropped / dropped |
Frames lost since the previous decoded delivery |
Analyzer fields:
| Kind | JavaScript / Python | Unit and shape / order |
|---|---|---|
| Level | channels / channels |
Processing-channel order; each item has linear-amplitude peak, linear-amplitude rms, and boolean clipped (a sample exceeded full scale) |
| Oscilloscope | sampleRate / sample_rate |
Hz |
| Oscilloscope | captureSampleCount / capture_sample_count |
Samples in the full capture |
| Oscilloscope | triggerOffset / trigger_offset |
Trigger position in samples from capture start |
| Oscilloscope | triggered / triggered |
True for a real trigger; false for an automatic sweep |
| Oscilloscope | encoding / encoding |
samples for raw points or minMax for ordered envelope points |
| Oscilloscope | sampleIndices / sample_indices |
[point] capture indices, paired by position with values |
| Oscilloscope | values / values |
[point] linear-amplitude values |
| Spectrum | sampleRate / sample_rate |
Hz |
| Spectrum | points / points |
FFT size exponent; FFT size is 2 ** points |
| Spectrum | binsTruncated / bins_truncated |
True when the highest bins were omitted to fit transport capacity |
| Spectrum | currentDb / current_db |
dBFS [bin], ascending frequency from DC |
| Spectrum | peakDb / peak_db |
Peak-held dBFS [bin], same order and length as current |
| Note Spectrogram | sampleRate / sample_rate |
Hz |
| Note Spectrogram | timeSeconds / time_seconds |
Observation time in seconds on the processing timeline |
| Note Spectrogram | firstMidi / first_midi |
21, the first piano-key MIDI note before fine-pitch offsets are applied |
| Note Spectrogram | hopSeconds / hop_seconds |
Nominal time step between analysis observations, in seconds |
| Note Spectrogram | frameIndex / frame_index |
Unsigned observation counter within the current analysis generation |
| Note Spectrogram | divisionsPerSemitone / divisions_per_semitone |
5; each semitone has bins at -40, -20, 0, +20, and +40 cents around its center |
| Note Spectrogram | generation / generation |
Non-zero analysis generation; a change indicates that analyzer state restarted |
| Note Spectrogram | levels / levels |
Pitch confidence in [0, 1] as JavaScript Float32Array[440] or Python tuple[440]; index i maps to MIDI firstMidi + (i - 2) / divisionsPerSemitone |
| Note Spectrogram | volumeDb / volume_db |
Volume in dB as JavaScript Float32Array[440] or Python tuple[440], with the same pitch indexing as levels; values include a 3 dB/octave correction above 100 Hz, and -240 dB means no level was measured |
| Spectrogram | sampleRate / sample_rate |
Hz |
| Spectrogram | timeSeconds / time_seconds |
Observation time in seconds on the processing timeline |
| Spectrogram | points / points |
FFT size exponent; FFT size is 2 ** points |
| Spectrogram | intensities / intensities |
uint8[256] display intensity, high-to-low log-frequency cells from index 0 through 255 |
| Stereo | sampleRate / sample_rate |
Hz |
| Stereo | discontinuity / discontinuity |
True when the sample delta is incomplete after truncation or a window change |
| Stereo | samples / samples |
JavaScript Float32Array[side0, mid0, ...]; Python tuple[(side, mid), ...]; linear amplitude where side is R-L and mid is L+R |
| Stereo | envelope / envelope |
Linear-amplitude [360] polar-angle bins in index order |
| Stereo | correlation / correlation |
Unitless stereo correlation in [-1, 1] |
| Stereo | balance / balance |
Right-versus-left energy balance in dB |
| Stereo | peakLeft / peak_left |
Left linear-amplitude peak |
| Stereo | peakRight / peak_right |
Right linear-amplitude peak |
frame.dropped reports loss since the previous decoded delivery. By contrast,
dropped_telemetry_frames on a Python stream and droppedTelemetryFrames on a
JavaScript stream or node are cumulative for that object’s lifetime.
Telemetry stays local: the library only passes decoded frames to in-process Python callbacks or callbacks in the browser page. It does not automatically collect, persist, or send telemetry over the network, and it does not collect device or user identifiers.
Other catalog telemetry remains metadata-only in v0.1. Integrated LUFS, BS.1770/EBU R128, true peak, and dynamics gain-reduction observations are not part of this API.