stream

stream(source, options?): Promise<AsyncGenerator<Float32Array<ArrayBufferLike>, any, any>>

Defined in: packages/pleco-xa/src/scripts/xa-fileio.js:55

Chunked audio reader (NOT true streaming — honesty note, 2026-07-02).

The whole source is decoded up front via decodeAudioData, then yielded in fixed-size sample windows: each block is blockLength SAMPLES and the window advances by hopLength samples, so blockLength > hopLength yields OVERLAPPING blocks. This is a simplified streaming contract — a true frame-based streamer would count block_length in FRAMES of frameLength/hopLength each and read incrementally. Memory use is O(file), not O(block). For live input use createMediaStreamProcessor instead.

With blockLength === hopLength the blocks are non-overlapping and lossless: ceil(N / blockLength) blocks whose concatenation reproduces the decoded source exactly (proof: examples/web/file-io.html).

Parameters

source

string | Blob | File | MediaStream | HTMLMediaElement

Audio source

options?

Streaming options

audioContext

AudioContext

Web Audio context (default: new AudioContext())

blockLength

number

Number of frames per block (default: 2048)

duration

number

Duration to stream in seconds (default: null, entire file)

fillValue

number

Fill value for incomplete blocks (default: 0.0)

frameLength

number

Frame length for analysis (default: 2048)

hopLength

number

Hop length between frames (default: 512)

mono

boolean

Convert to mono (default: true)

offset

number

Start time in seconds (default: 0.0)

onBlock

Function

Callback for each audio block

Returns

Promise<AsyncGenerator<Float32Array<ArrayBufferLike>, any, any>>

Async generator yielding audio blocks

Example

// Stream audio file in 2048-sample blocks
const file = document.getElementById('audio-input').files[0];
const generator = await stream(file, {
  blockLength: 2048,
  mono: true,
  onBlock: (block) => {
    // Process each block in real-time
    const features = mfcc(block);
    console.log('Block features:', features);
  }
});

// Iterate through blocks
for await (const block of generator) {
  // Process block
  console.log('Block shape:', block.length);
}