node-ffmpeg

Documentation · API reference · Migration guide

A small, typed Node.js wrapper around the FFmpeg and ffprobe command-line tools. It keeps the original ffmpeg package API—Promise or callback construction, chainable setters, conversion, frame extraction, audio extraction, and watermarks—while using modern Node.js primitives.

Requirements

• Node.js 24 or newer
• ffmpeg and ffprobe on PATH, or explicit executable paths

The package intentionally does not download binaries. This keeps installation small and lets the application choose the FFmpeg build and codecs it needs.

npm install ffmpeg

Quick start

import ffmpeg from 'ffmpeg';

const video = await ffmpeg('/media/input.mp4');

video.on('progress', ({ percent, time }) => {
  console.log(percent === undefined ? `${time}s` : `${percent.toFixed(1)}% (${time}s)`);
});

await video
  .setVideoCodec('libx264')
  .setVideoBitRate(2_000)
  .setAudioCodec('aac')
  .setAudioBitRate(192)
  .setVideoSize('1280x?', true, true, 'black')
  .save('/media/output.mp4');

CommonJS remains callable, as in 0.0.4:

const ffmpeg = require('ffmpeg');
const video = await new ffmpeg('/media/input.mp4');
await video.setVideoCodec('copy').setAudioCodec('copy').save('/media/copy.mp4');

The legacy callback API also remains available:

new ffmpeg('/media/input.mp4', (error, video) => {
  if (error) return console.error(error);
  video.save('/media/output.mp4', (saveError, output) => {
    if (saveError) console.error(saveError);
    else console.log(output);
  });
});

For new TypeScript code, the named factory is the clearest form:

import { create } from 'ffmpeg';

const video = await create('/media/input.mp4', {
  timeout: 120_000,
  overwrite: true,
});

For services that process several files with one fixed FFmpeg installation, inspect capabilities once with an isolated client:

import { createClient } from 'ffmpeg';

const client = await createClient({ overwrite: true, timeout: 120_000 });
const video = await client.open('/media/input.mp4');

Client executable paths, environment, and working directory are snapshotted at creation. Per-open settings may adjust timeout, buffering, overwrite behavior, encoding, and cancellation without invalidating the cached capabilities.

Executable paths

Set paths globally for legacy applications:

ffmpeg.bin = '/opt/ffmpeg/bin/ffmpeg';
ffmpeg.ffprobeBin = '/opt/ffmpeg/bin/ffprobe';

Or per operation:

await ffmpeg('/media/input.mp4', {
  ffmpegPath: '/opt/ffmpeg/bin/ffmpeg',
  ffprobePath: '/opt/ffmpeg/bin/ffprobe',
});

When an absolute ffmpegPath is supplied and ffprobePath is omitted, a sibling ffprobe executable is inferred. Hierarchical URLs such as HTTP, HTTPS, and RTSP are accepted as inputs when supported by the installed FFmpeg build. Non-hierarchical virtual inputs, stdin (-), and Node.js streams are not supported as primary inputs because initialization probes the source first.

Settings

Setting	Default	Meaning
encoding	utf8	Process output encoding
timeout	0	Maximum operation time in milliseconds; 0 disables it
maxBuffer	16 MiB	Conversion output tail and maximum complete probe output
overwrite	false	Use -y; otherwise -n prevents interactive hangs
ffmpegPath	ffmpeg	FFmpeg executable
ffprobePath	ffprobe	ffprobe executable
signal	—	AbortSignal used to cancel an operation
cwd, env	inherited	Child-process working directory and environment

Long-running conversions retain only the most recent maxBuffer bytes of stdout and stderr. Probe and configuration output must remain complete: if stdout exceeds the limit, the operation fails with error 119 instead of parsing a truncated document.

API

All setters are chainable:

• Video: setDisableVideo, setVideoFormat, setVideoCodec, setVideoBitRate, setVideoFrameRate, setVideoStartTime, setVideoDuration, setVideoAspectRatio, setVideoSize, setVideoQuality
• Audio: setDisableAudio, setAudioCodec, setAudioFrequency, setAudioChannels, setAudioBitRate, setAudioQuality
• General: setMetadata, setThreads, setWatermark, addInput, addCommand, addOutputOption, addFilterComplex, getCommand
• Execution: save, fnExtractSoundToMP3, fnExtractFrameToJPG, fnAddWatermark

copy is accepted by both codec setters. Repeated custom options such as multiple -map or -metadata entries are supported.

Terminal methods consume the current fluent options at invocation. Their validation and process errors always arrive through Promise rejection or the optional callback. Input/settings validation performed by ffmpeg(), new ffmpeg(), create() and client.open() remains synchronous, as do setters and getCommand(). Concurrent operations on one Video use isolated option snapshots. Their shared lifecycle events may interleave, but every event includes an immutable operation context for correlation.

Metadata

video.metadata preserves the original package shape (duration, video, audio, and common tags) and adds the complete ffprobe response at video.metadata.raw. Available formats and encoders are exposed at video.info_configuration.

Progress and lifecycle events

video.on('start', (command) => console.log(command));
video.on('progress', (progress, operation) => {
  console.log(operation.operationId, operation.destination, progress.percent);
});
video.on('stderr', (chunk) => process.stderr.write(chunk));
video.on('end', (result) => console.log(result.code));
video.on('error', (error) => console.error(error)); // optional

An error listener is optional: failed Promise operations reject normally instead of causing an unhandled EventEmitter error.

Frame extraction

const files = await video.fnExtractFrameToJPG('/media/frames', {
  start_time: '00:00:10',
  every_n_seconds: 5,
  number: 10,
  size: '640x?',
  quality: 2,
  file_name: 'preview_%s',
});

Only one of every_n_frames, every_n_seconds, or every_n_percentage may be set. Returned paths are limited to files matching the extraction pattern, rather than every file in the directory.

Custom FFmpeg options

await video
  .addCommand('-movflags', '+faststart')
  .addCommand('-map', '0:v:0')
  .addCommand('-map', '0:a:0?')
  .save('/media/output.mp4');

Arguments are passed directly to spawn with shell: false; do not add shell quotes. Custom input, command, output-option, and filter methods are trusted escape hatches and must not receive unvalidated user strings. Output destinations beginning with - are rejected; use an explicit ./-name.ext or absolute path when the filename intentionally starts with a dash.

Migrating from 0.0.4

• Node.js 24+ and ffprobe are now required.
• Native Promises replace when; normal await and .then() usage is unchanged.
• Errors are FfmpegError instances with the historical numeric code and msg fields.
• Watermark compass positions now follow their conventional meaning (for example, NE is top-right). This fixes the old east/west inversion.
• Bitrates use modern stream-specific flags (-b:v and -b:a); numeric values are interpreted as kbit/s.
• Existing outputs are protected with -n. Set overwrite: true to use -y.
• The project publishes both ESM and CommonJS and includes its own TypeScript declarations; @types/ffmpeg is no longer needed.

See AUDIT.md for the code and issue audit and CHANGELOG.md for the release summary.

Security

FFmpeg processes untrusted and highly complex media. Keep the system FFmpeg build patched, apply resource limits appropriate to your service, and see SECURITY.md before accepting untrusted input.

License

MIT © Damiano Ciarla