mfx/site/versioned_docs/version-0.8.2/tutorial/pipelines.md

In-browser video editing toolkit, with effects accelerated by WebGL

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sidebar_position: 2
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# Pipelines

A "pipeline" is a simple representation of streams of data that load → transform → store the video data.

## A complete pipeline

```js title="pipeline.js"
import {
  decode,
  encode,
  effect,
  visual,
  writeToFile,
} from "mfx";

// Files can be fetched locally
const file = await fetch("https://example.com/myvideo.mp4");

// Decode video container, returns each track as a WebStream
const { video, audio } = await decode(file, "video/mp4", {
  // Addresses Chromium WebCodecs bug, Set to true for HEVC or if "Can't readback frame textures" is thrown. Has ~10% performance impact.
  forceDecodeToSoftware: false,
});

// Hardware accelerated (WebGL2) effect pipeline
const videoOutput = effect(video, [
  // Apply zoom out effect
  visual.zoom({ factor: 0.5, x: 0.5, y: 0.25 }),
  visual.add(video2, {}),
]);

// Readable WebStream
const outputStream = encode({
  mimeType: `video/webm; codecs="vp8,opus"`, // Transcode to WebM VP8 (video) and Opus (audio)
  video: {
    ...video.track.config, // Inherit configuration from input video
    stream: videoOutput,
    width: 640,
    height: 360,
    bitrate: 1e6,
    framerate: 30,
  },
  audio: {
    ...audio.track.config, // Inherit configuration from input audio
    stream: audio
  }
});

// Opens a save dialog in the browser
await writeToFile(outputStream, "output.webm");
```