PcmFrame class

One PCM frame — raw post-DSP audio samples captured at the player's output, before they're handed to the OS audio driver.

Emitted on PlayerStream.pcm at the rate configured in SpectrumSettings.emitInterval (default ~30 Hz). Use this for time-domain visualisations the FFT pipeline can't express: scrolling waveforms, accurate VU/peak meters, oscilloscopes, vectorscopes, custom feature extractors that need raw amplitude.

For a frequency-domain visualizer (spectrum bars, glow effects), prefer FftFrame from PlayerStream.fft. The two streams share the same upstream tap, so subscribing to both costs only the duplicate FFT computation, not a second tap.

Example — a peak-hold VU meter:

double peak = 0;
player.stream.pcm.listen((frame) {
  for (final s in frame.samples) {
    if (s.abs() > peak) peak = s.abs();
  }
  peak *= 0.92; // decay
  _vuController.value = peak;
});

Constructors

PcmFrame({required Float32List samples, required Duration timestamp, required int sampleRate, required int channels})
Creates a frame. Only used internally by the spectrum pipeline.
const

Properties

channels → int
Channel count — 1 for mono, 2 for stereo, 6 for 5.1, etc. Combine with samples.length to compute samplesPerChannel.
final
hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
sampleRate → int
Sample rate in Hz (typically 44100 or 48000).
final
samples → Float32List
Interleaved Float32 samples in the range [-1.0, +1.0]. For stereo audio the layout is L, R, L, R, …; for 5.1 it's L, R, C, LFE, Ls, Rs, …. Length is samplesPerChannel * channels. Total samples per channel: samples.length ~/ channels.
final
samplesPerChannel → int
Convenience: number of samples per channel — samples.length / channels.
no setter
timestamp → Duration
Wall-clock timestamp at which the audio output captured this frame. Process-monotonic — derived from libmpv's internal mp_time_ns(), which counts from the moment the engine initialised, not from the start of the track. Use it to detect fresh frames or to align side-effects in real time; for the playback PTS of these samples, read PlayerStream.position / PlayerStream.audioPts instead.
final

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited