lossless-cut/src/ffmpeg.js

const execa = require('execa');
const bluebird = require('bluebird');
const which = bluebird.promisify(require('which'));
const path = require('path');
const fs = require('fs');
const fileType = require('file-type');
const readChunk = require('read-chunk');
const _ = require('lodash');
const readline = require('readline');
const moment = require('moment');

const util = require('./util');

bluebird.promisifyAll(fs);


function showFfmpegFail(err) {
  alert(`Failed to run ffmpeg:\n${err.stack}`);
  console.error(err.stack);
}

function getWithExt(name) {
  return process.platform === 'win32' ? `${name}.exe` : name;
}

function canExecuteFfmpeg(ffmpegPath) {
  return execa(ffmpegPath, ['-version']);
}

function getFfmpegPath() {
  const internalFfmpeg = path.join(__dirname, '..', 'app.asar.unpacked', 'ffmpeg', getWithExt('ffmpeg'));
  return canExecuteFfmpeg(internalFfmpeg)
    .then(() => internalFfmpeg)
    .catch(() => {
      console.log('Internal ffmpeg unavail');
      return which('ffmpeg');
    });
}

function handleProgress(process, cutDuration, onProgress) {
  const rl = readline.createInterface({ input: process.stderr });
  rl.on('line', (line) => {
    try {
      const match = line.match(/frame=\s*[^\s]+\s+fps=\s*[^\s]+\s+q=\s*[^\s]+\s+(?:size|Lsize)=\s*[^\s]+\s+time=\s*([^\s]+)\s+/); // eslint-disable-line max-len
      if (!match) return;

      const str = match[1];
      console.log(str);
      const progressTime = moment.duration(str).asSeconds();
      console.log(progressTime);
      onProgress(progressTime / cutDuration);
    } catch (err) {
      console.log('Failed to parse ffmpeg progress line', err);
    }
  });
}

async function cut({
  customOutDir, filePath, format, cutFrom, cutTo, cutToApparent, videoDuration, rotation,
  includeAllStreams, onProgress, stripAudio, keyframeCut,
}) {
  const ext = path.extname(filePath) || `.${format}`;
  const cutSpecification = `${util.formatDuration(cutFrom, true)}-${util.formatDuration(cutToApparent, true)}`;

  const outPath = util.getOutPath(customOutDir, filePath, `${cutSpecification}${ext}`);

  console.log('Cutting from', cutFrom, 'to', cutToApparent);

  const cutDuration = cutToApparent - cutFrom;

  // https://github.com/mifi/lossless-cut/issues/50
  const cutFromArgs = cutFrom === 0 ? [] : ['-ss', cutFrom];
  const cutToArgs = cutTo === undefined || cutTo === videoDuration ? [] : ['-t', cutDuration];

  const inputCutArgs = keyframeCut ? [
    ...cutFromArgs,
    '-i', filePath,
    ...cutToArgs,
    '-avoid_negative_ts', 'make_zero',
  ] : [
    '-i', filePath,
    ...cutFromArgs,
    ...cutToArgs,
  ];

  const rotationArgs = rotation !== undefined ? ['-metadata:s:v:0', `rotate=${rotation}`] : [];
  const ffmpegArgs = [
    ...inputCutArgs,

    ...(stripAudio ? ['-an'] : ['-acodec', 'copy']),

    '-vcodec', 'copy',
    '-scodec', 'copy',

    ...(includeAllStreams ? ['-map', '0'] : []),
    '-map_metadata', '0',

    ...rotationArgs,

    '-f', format, '-y', outPath,
  ];

  console.log('ffmpeg', ffmpegArgs.join(' '));

  onProgress(0);

  const ffmpegPath = await getFfmpegPath();
  const process = execa(ffmpegPath, ffmpegArgs);
  handleProgress(process, cutDuration, onProgress);
  const result = await process;
  console.log(result.stdout);

  await util.transferTimestamps(filePath, outPath);
}

async function html5ify(filePath, outPath, encodeVideo) {
  console.log('Making HTML5 friendly version', { filePath, outPath, encodeVideo });

  const videoArgs = encodeVideo
    ? ['-vf', 'scale=-2:400,format=yuv420p', '-sws_flags', 'neighbor', '-vcodec', 'libx264', '-profile:v', 'baseline', '-x264opts', 'level=3.0', '-preset:v', 'ultrafast', '-crf', '28']
    : ['-vcodec', 'copy'];

  const ffmpegArgs = [
    '-i', filePath, ...videoArgs, '-an',
    '-y', outPath,
  ];

  console.log('ffmpeg', ffmpegArgs.join(' '));

  const ffmpegPath = await getFfmpegPath();
  const process = execa(ffmpegPath, ffmpegArgs);
  const result = await process;
  console.log(result.stdout);

  await util.transferTimestamps(filePath, outPath);
}

/**
 * ffmpeg only supports encoding certain formats, and some of the detected input
 * formats are not the same as the names used for encoding.
 * Therefore we have to map between detected format and encode format
 * See also ffmpeg -formats
 */
function mapFormat(requestedFormat) {
  switch (requestedFormat) {
    // These two cmds produce identical output, so we assume that encoding "ipod" means encoding m4a
    // ffmpeg -i example.aac -c copy OutputFile2.m4a
    // ffmpeg -i example.aac -c copy -f ipod OutputFile.m4a
    // See also https://github.com/mifi/lossless-cut/issues/28
    case 'm4a': return 'ipod';
    case 'aac': return 'ipod';
    default: return requestedFormat;
  }
}

function determineOutputFormat(ffprobeFormats, ft) {
  if (_.includes(ffprobeFormats, ft.ext)) return ft.ext;
  return ffprobeFormats[0] || undefined;
}

function getFormat(filePath) {
  return bluebird.try(() => {
    console.log('getFormat', filePath);

    return getFfmpegPath()
      .then(ffmpegPath => path.join(path.dirname(ffmpegPath), getWithExt('ffprobe')))
      .then(ffprobePath => execa(ffprobePath, [
        '-of', 'json', '-show_format', '-i', filePath,
      ]))
      .then((result) => {
        const formatsStr = JSON.parse(result.stdout).format.format_name;
        console.log('formats', formatsStr);
        const formats = (formatsStr || '').split(',');

        // ffprobe sometimes returns a list of formats, try to be a bit smarter about it.
        return readChunk(filePath, 0, 4100)
          .then((bytes) => {
            const ft = fileType(bytes) || {};
            console.log(`fileType detected format ${JSON.stringify(ft)}`);
            const assumedFormat = determineOutputFormat(formats, ft);
            return mapFormat(assumedFormat);
          });
      });
  });
}

module.exports = {
  cut,
  getFormat,
  showFfmpegFail,
  html5ify,
};