How to use stream-mmmagic - 3 common examples

save(file, readStream, cb) {
    debug('save', file)
    if (file.metadata.secure && (!file.crypto.algorithm || !file.crypto.passphrase)) {
      return cb('You did not provide a valid crypto algorithm and/or passphrase.')
    }

    detectMime(readStream, (err, mime, dataStream) => {
      if (err) {
        return cb(err)
      }

      // set default mime value if libmagic fails
      if (mime === null) {
        mime = { type: 'application/octet-stream' }
      }

      // perform additional lookup when mime type is text/plain
      mime.type = mime.type === 'text/plain'
        ? mimeType.lookup(file.filename) || 'text/plain'
        : mime.type

      // detect if file is blacklisted
      const { blacklist } = this._storageConfig

save(file, readStream, cb) {
    debug('save', file)
    if (file.metadata.secure && (!file.crypto.algorithm || !file.crypto.passphrase)) {
      return cb('You did not provide a valid crypto algorithm and/or passphrase.')
    }

    detectMime(readStream, (err, mime, dataStream) => {
      if (err) {
        return cb(err)
      }

      // set default mime value if libmagic fails
      if (mime === null) {
        mime = { type: 'application/octet-stream' }
      }

      // perform additional lookup when mime type is text/plain
      mime.type = mime.type === 'text/plain'
        ? mimeType.lookup(file.filename) || 'text/plain'
        : mime.type

      // detect if file is blacklisted
      const { blacklist } = this._storageConfig

var _ = require("underscore");
var path = require("path");
var VideoConverter = require("./VideoConverter.js");
var Stream = require('stream');
var magic = require('stream-mmmagic');
magic.config.magicFile = "(null),"+path.join(__dirname,"../misc/magic");
var presets = require("./presets.js");


/**
 *
 *
 * @param options configuration options
 * @param options.ffmpeg {String} path to ffmpeg
 * @param options.im {String} path to imagemagick
 * @constructor
 */
function MediaConverter(options) {
    options = _.defaults(options || {}, {
        programs: {
            // Path to the ffmpeg program
            ffmpeg: 'ffmpeg',