konowebcodecs/docs/api.md

API

• createFFmpeg()
  • ffmpeg.load
  • ffmpeg.run
  • ffmpeg.FS
  • ffmpeg.setLogging
  • ffmpeg.setLogger
  • ffmpeg.setProgress

---

createFFmpeg(options): ffmpeg

createFFmpeg is a factory function that creates a ffmpeg instance.

Arguments:

• options an object of customized options
  • corePath path for ffmpeg-core.js script
  • log a boolean to turn on all logs, default is false
  • logger a function to get log messages, a quick example is ({ message }) => console.log(message)
  • progress a function to trace the progress, a quick example is p => console.log(p)

Examples:

const { createFFmpeg } = FFmpeg;
const ffmpeg = createFFmpeg({
  corePath: "./node_modules/@ffmpeg/core/dist/ffmpeg-core.js",
  log: true,
});

ffmpeg.load(): Promise

Load ffmpeg.wasm-core script.

In browser environment, the ffmpeg.wasm-core script is fetch from CDN and can be assign to a local path by assigning corePath. In node environment, we use dynamic require and the default corePath is $ffmpeg/core.

Typically the load() func might take few seconds to minutes to complete, better to do it as early as possible.

Examples:

(async () => {
  await ffmpeg.load();
})();

ffmpeg.run(...args): Promise

This is the major function in ffmpeg.wasm, you can just imagine it as ffmpeg native cli and what you need to pass is the same.

Arguments:

• args string arguments just like cli tool.

Examples:

(async () => {
  await ffmpeg.run('-i', 'flame.avi', '-s', '1920x1080', 'output.mp4');
  /* equals to `$ ffmpeg -i flame.avi -s 1920x1080 output.mp4` */
})();

ffmpeg.FS(method, ...args): any

Run FS operations.

For input/output file of ffmpeg.wasm, it is required to save them to MEMFS first so that ffmpeg.wasm is able to consume them. Here we rely on the FS methods provided by Emscripten.

For more info, check https://emscripten.org/docs/api_reference/Filesystem-API.html

Arguments:

• method string method name
• args arguments to pass to method

Examples:

/* Write data to MEMFS, need to use Uint8Array for binary data */
ffmpeg.FS('writeFile', 'video.avi', new Uint8Array(...));
/* Read data from MEMFS */
ffmpeg.FS('readFile', 'video.mp4');
/* Delete file in MEMFS */
ffmpeg.FS('unlink', 'video.mp4');

ffmpeg.setLogging(logging)

Control whether to output log information to console

Arguments

• logging a boolean to turn of/off log messages in console

Examples:

ffmpeg.setLogging(true);

ffmpeg.setLogger(logger)

Set customer logger to get ffmpeg.wasm output messages.

Arguments

• logger a function to handle the messages

Examples:

ffmpeg.setLogger(({ type, message }) => {
  console.log(type, message);
  /*
   * type can be one of following:
   *
   * info: internal workflow debug messages
   * fferr: ffmpeg native stderr output
   * ffout: ffmpeg native stdout output
   */
});

ffmpeg.setProgress(progress)

Progress handler to get current progress of ffmpeg command.

Arguments

• progress a function to handle progress info

Examples:

ffmpeg.setProgress(({ ratio }) => {
  console.log(ratio);
  /*
   * ratio is a float number between 0 to 1.
   */
});