@corewire/audio-source

import { FileSource, LiveSource, UrlSource } from '@corewire/audio-source';

Every source implements AudioSource from @corewire/airplay and produces 44100 Hz stereo signed 16-bit big-endian PCM. Every class name ends in Source, so none of them shadows a global such as File or URL. See URLs and audio streams.

Sources

Export	Description
abstract class BufferAudioSource	A source over a decoded PCM buffer. constructor(buffer: Buffer, duration: number, frameSize?: number); readFrames(), reset(), start(), stop()
class UrlSource extends BufferAudioSource	static fromUrl(url: string, options?: UrlSourceOptions): Promise<UrlSource>. Detects MP3, OGG Vorbis, FLAC, WAV and QOA; raw PCM needs format: 'pcm'
class FileSource extends BufferAudioSource	static fromPath(path: string): Promise<FileSource>. MP3, OGG and WAV; raw PCM otherwise
class Mp3Source extends BufferAudioSource	static fromBuffer(data: Buffer): Promise<Mp3Source>, static fromUrl(url: string, options?: FetchOptions): Promise<Mp3Source>
class OggSource extends BufferAudioSource	static fromBuffer(data: Buffer): Promise<OggSource>, static fromUrl(url: string, options?: FetchOptions): Promise<OggSource>
class WavSource extends BufferAudioSource	static fromBuffer(data: Buffer): Promise<WavSource>, static fromUrl(url: string, options?: FetchOptions): Promise<WavSource>
class PcmSource extends BufferAudioSource	constructor(pcm: Buffer, options?: PcmSourceOptions); resamples to 44100 Hz when needed
class SineWaveSource extends BufferAudioSource	constructor(options: SineWaveSourceOptions); a tone with a 50 ms fade in and out
class FfmpegSource implements AudioSource	constructor(options: FfmpegSourceOptions). Decodes with ffmpeg from the PATH while streaming; stats reports its buffer (bufferedBytes, peakBufferedBytes, bufferLimit, paused). reset() makes the next start() decode from the beginning
class LiveSource implements AudioSource	constructor(options?: LiveSourceOptions). A ring buffer: write(data: Buffer): number, end(): void, available, capacity, ended. duration is Infinity

The classes with a factory have a private constructor. The decoders run in a worker thread (decode-worker.mjs in the package). When that file cannot load, decoding runs on the calling thread instead.

Options

Type	Definition
FetchOptions	{signal?: AbortSignal; maxBytes?: number; timeoutMs?: number}; maxBytes defaults to 64 MiB, timeoutMs to 30000
UrlSourceOptions	FetchOptions & {format?: 'encoded' | 'pcm'}; encoded when omitted
PcmSourceOptions	{sampleRate?: number}; 44100 when omitted
SineWaveSourceOptions	{duration: number; frequency?: number; sampleRate?: number; channels?: number}; seconds, 440 Hz, 44100 Hz and 2 channels when omitted
FfmpegSourceOptions	{path: string; duration: number}; the file and its length in seconds
LiveSourceOptions	{bufferDuration?: number}; seconds of audio the ring buffer holds, 2 when omitted

AudioSource

Member	Description
duration: number	Seconds
readFrames(count: number): Promise<Buffer | null>	Null when the source ran out
reset(): Promise<void>	Back to the start
start(): Promise<void>	Called once before the first read
stop(): Promise<void>	Called when the stream ends, fails or is cancelled