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We are phasing out Remotion WebCodecs and are moving to Mediabunny!

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This package is experimental.
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getPartialAudioData()v4.0.328

Part of the @remotion/webcodecs package.

Extracts audio data from a specific time window of a media file and returns it as a Float32Array.

Extract audio data from 10-20 seconds
import {getPartialAudioData} from '@remotion/webcodecs';

const audioData = await getPartialAudioData({
  src: 'https://remotion.media/audio.wav',
  fromSeconds: 10,
  toSeconds: 20,
  channelIndex: 0, // Left channel for stereo audio
  signal: new AbortController().signal,
});

console.log('Audio samples:', audioData.length);
console.log('First sample value:', audioData[0]);

API​

src​

string

A URL pointing to a media file, or a File/Blob object.

If it is a remote URL, it must support CORS and the server must support byte-range requests for efficient seeking.

fromSeconds​

number

The start time in seconds from which to extract audio data.

toSeconds​

number

The end time in seconds until which to extract audio data.

channelIndex​

number

The audio channel index to extract. For stereo audio:

  • 0 = Left channel
  • 1 = Right channel

For mono audio, use 0.

signal​

AbortSignal

An AbortSignal to cancel the operation.

Using AbortController
import {getPartialAudioData} from '@remotion/webcodecs';
import {hasBeenAborted} from '@remotion/media-parser';

const controller = new AbortController();

// Cancel after 5 seconds
setTimeout(() => controller.abort(), 5000);

try {
  const audioData = await getPartialAudioData({
    src: 'https://remotion.media/audio.wav',
    fromSeconds: 0,
    toSeconds: 30,
    channelIndex: 0,
    signal: controller.signal,
  });
} catch (err) {
  if (hasBeenAborted(err)) {
    console.log('Operation was cancelled');
  }
}

Return value​

Returns a Promise<Float32Array> containing the audio samples for the requested time window and channel.

The sample values are normalized floating-point numbers typically in the range of -1.0 to 1.0.

Notes​

  • The function uses a small buffer (0.1 seconds) around the requested time window to ensure accurate extraction of chunks that span across boundaries
  • For multi-channel audio, samples are de-interleaved to extract the specific channel
  • The function leverages @remotion/media-parser for parsing and WebCodecs for efficient audio decoding
  • Sample rate and other audio characteristics depend on the source media file

See also​