node.md

Node API

Reference

extractAlpha() Method

import {spawn} from 'child_process';
import {extractAlpha, filterComplex} from 'video-renderer/node';

const ffmpegProc = spawn('ffmpeg', [
  '-i',
  __dirname + '/loop.gif',
  '-movflags',
  'faststart',
  // pix_fmt is needed for converting gifs
  '-pix_fmt',
  'yuv420p',
  '-filter_complex',
  filterComplex(extractAlpha()),
  __dirname + '/loop.mp4',
]);

Generates the complex filter graph required to convert a gif/video with transparent background into a video that uses a separate greyscale image to encode the alpha channel as a mask. This can be used on the client side with an asset kind of AssetKind.VideoWithAlpha. GIFs are currently not supported on the client side without this transformation.

filterComplex() Method

import {spawn} from 'child_process';
import {filterComplex} from 'video-renderer/node';

const ffmpegProc = spawn('ffmpeg', [
  '-i',
  __dirname + '/input.mp4',
  '-movflags',
  'faststart',
  '-filter_complex',
  filterComplex([
    {
      name: 'trim',
      args: {
        start: 0,
        end: 5,
      },
    },
  ]),
  __dirname + '/output.mp4',
]);

Takes the ComplexFilter objects and generates the filter_complex string that is expected by the ffmpeg command line tool.