Refactor: split out code into files + separate image/video processing

lib/image/gmagick.js

@@ -0,0 +1,66 @@
+const gm = require('gm')
+
+const DEFAULT_PHOTO_QUALITY = 90 // percent
+
+exports.prepare = function (source, options) {
+  // start processing with GraphicsMagick
+  const image = gm(source)
+
+  // read baked-in orientation info, and output a rotated image with orientation=0
+  image.autoOrient()
+
+  // optional watermark
+  const cropping = options.width && options.height
+  if (options.watermark && !cropping) {
+    image.composite(options.watermark.file)
+    if (options.watermark.position === 'Repeat') {
+      image.tile(options.watermark.file)
+    } else if (typeof options.watermark.position === 'string') {
+      image.gravity(options.watermark.position)
+    } else {
+      image.gravity('SouthEast')
+    }
+  }
+
+  // resize if necessary
+  if (cropping) {
+    // crop to the exact height and weight
+    image.resize(options.width, options.height, '^')
+    image.gravity('Center')
+    image.crop(options.width, options.height)
+    image.out('+repage')
+  } else if (options.height) {
+    // resize to a maximum height
+    image.resize(null, options.height, '>')
+  } else if (options.width) {
+    // resize to a maximum width
+    image.resize(options.width, null, '>')
+  }
+
+  // default quality, for typical web-friendly sizes
+  image.quality(options.quality || DEFAULT_PHOTO_QUALITY)
+
+  // apply custom post-processing arguments (sharpen, brightness...)
+  exports.addRawArgs(image, options.args)
+
+  return image
+}
+
+/*
+  Applies an array of GraphicsMagick string arguments to a <gm> instance
+  e.g. apply(image, ['--modulate 120'])
+*/
+exports.addRawArgs = function (image, args) {
+  if (args && args.length) {
+    args.forEach(arg => {
+      const index = arg.indexOf(' ')
+      if (index === -1) {
+        image.out(arg)
+      } else {
+        const command = arg.substr(0, index)
+        const values = arg.substr(index + 1)
+        image.out(command, values)
+      }
+    })
+  }
+}

lib/index.js

@@ -1,16 +1,13 @@
 const async = require('async')
 const fs = require('fs')
-const gm = require('gm')
 const mkdirp = require('mkdirp')
 const path = require('path')
-const gifsicle = require('./gifsicle')
-const gmargs = require('./gmargs')
-const ffmpeg = require('./ffmpeg')
+const gifsicle = require('./image/gifsicle')
+const gmagick = require('./image/gmagick')
+const ffmpeg = require('./video/ffmpeg')
+const ffargs = require('./video/ffargs')
 
 const GIF_FILE = /\.gif$/i
-const DEFAULT_PHOTO_QUALITY = 90 // percent
-const DEFAULT_AUDIO_BITRATE = '96k'
-const DEFAULT_VIDEO_FPS = 25
 
 /*
   Convert and/or resize an image
@@ -30,45 +27,8 @@ exports.image = function (source, target, options, callback) {
     }
   }
 
-  // start processing with GraphicsMagick
-  const image = gm(source)
-
-  // read baked-in orientation info, and output a rotated image with orientation=0
-  image.autoOrient()
-
-  // optional watermark
-  const cropping = options.width && options.height
-  if (options.watermark && !cropping) {
-    image.composite(options.watermark.file)
-    if (options.watermark.position === 'Repeat') {
-      image.tile(options.watermark.file)
-    } else if (typeof options.watermark.position === 'string') {
-      image.gravity(options.watermark.position)
-    } else {
-      image.gravity('SouthEast')
-    }
-  }
-
-  // resize if necessary
-  if (cropping) {
-    // crop to the exact height and weight
-    image.resize(options.width, options.height, '^')
-    image.gravity('Center')
-    image.crop(options.width, options.height)
-    image.out('+repage')
-  } else if (options.height) {
-    // resize to a maximum height
-    image.resize(null, options.height, '>')
-  } else if (options.width) {
-    // resize to a maximum width
-    image.resize(options.width, null, '>')
-  }
-
-  // default quality, for typical web-friendly sizes
-  image.quality(options.quality || DEFAULT_PHOTO_QUALITY)
-  // apply custom post-processing arguments (sharpen, brightness...)
-  gmargs.apply(image, options.args)
-  // write the output image
+  // process the image with GraphicsMagick
+  const image = gmagick.prepare(source, options)
   image.write(target, callback)
 }
 
@@ -80,33 +40,8 @@ exports.video = function (source, target, options, callback) {
   // create target folder if needed
   mkdirp.sync(path.dirname(target))
 
-  // common options
-  const args = ['-i', source, '-r', DEFAULT_VIDEO_FPS, '-vsync', '2', '-movflags', '+faststart', '-ab', DEFAULT_AUDIO_BITRATE]
-
-  // output to mp4 or webm which are well read on the web
-  if (options.format === 'webm') {
-    args.push('-f', 'webm', '-vcodec', 'libvpx-vp9', '-strict', '-2')
-  } else {
-    args.push('-f', 'mp4', '-vcodec', 'libx264')
-  }
-
-  // set average bitrate or perceptual quality
-  if (options.bitrate) {
-    args.push('-b:v', options.bitrate)
-  } else {
-    // TODO: add configurable CRF value
-    args.push('-b:v', 0, '-crf', 20)
-  }
-
-  // AVCHD/MTS videos need a full-frame export to avoid interlacing artefacts
-  if (path.extname(source).toLowerCase() === '.mts') {
-    args.push('-vf', 'yadif=1')
-  }
-
-  // target filename
-  args.push('-y', target)
-
-  // return a EventEmitter to follow progress, since this can take a long time
+  // run ffmpeg to create the downsized video
+  const args = ffargs.prepare(source, target, options)
   return ffmpeg.exec(args, callback)
 }
 

lib/video/ffargs.js

@@ -0,0 +1,44 @@
+const path = require('path')
+
+const DEFAULT_AUDIO_BITRATE = '96k'
+const DEFAULT_VIDEO_FPS = 25
+// const ENCODER_CRF_MAX = { h264: 51, vpx: 63 }
+
+exports.prepare = function (source, target, options) {
+  // source file
+  const args = ['-i', source]
+
+  // output framerate
+  args.push('-r', DEFAULT_VIDEO_FPS)
+
+  // misc options
+  args.push('-vsync', '2', '-movflags', '+faststart')
+
+  // audio bitrate
+  args.push('-ab', DEFAULT_AUDIO_BITRATE)
+
+  // output to mp4 or webm which are well read on the web
+  if (options.format === 'webm') {
+    args.push('-f', 'webm', '-vcodec', 'libvpx-vp9', '-strict', '-2')
+  } else {
+    args.push('-f', 'mp4', '-vcodec', 'libx264')
+  }
+
+  // set average video bitrate or perceptual quality
+  if (options.bitrate) {
+    args.push('-b:v', options.bitrate)
+  } else {
+    // TODO: add configurable CRF value
+    args.push('-b:v', 0, '-crf', 20)
+  }
+
+  // AVCHD/MTS videos need a full-frame export to avoid interlacing artefacts
+  if (path.extname(source).toLowerCase() === '.mts') {
+    args.push('-vf', 'yadif=1')
+  }
+
+  // target filename
+  args.push('-y', target)
+
+  return args
+}

package.json

@@ -4,7 +4,7 @@
   "description": "Convert / resize / transcode photos & videos to be web-friendly",
   "main": "lib/index.js",
   "scripts": {
-    "test": "tape test/*.js | tap-spec",
+    "test": "tape test/**/*.js | tap-spec",
     "pretest": "standard && require-lint"
   },
   "author": "thumbsup",

test/gmargs.js → test/image/gmagick.js

@@ -1,4 +1,4 @@
-const gmargs = require('../lib/gmargs')
+const gmagick = require('../../lib/image/gmagick')
 const sinon = require('sinon')
 const tape = require('tape')
 
@@ -11,23 +11,23 @@ function gm () {
 tape('no arguments', t => {
   t.plan(1)
   const image = gm()
-  gmargs.apply(image, undefined)
+  gmagick.addRawArgs(image, undefined)
   t.equal(image.out.callCount, 0)
   t.end()
 })
 
 tape('empty array of arguments', t => {
   t.plan(1)
   const image = gm()
-  gmargs.apply(image, [])
+  gmagick.addRawArgs(image, [])
   t.equal(image.out.callCount, 0)
   t.end()
 })
 
 tape('single argument with no values', t => {
   t.plan(2)
   const image = gm()
-  gmargs.apply(image, ['-equalize'])
+  gmagick.addRawArgs(image, ['-equalize'])
   t.equal(image.out.callCount, 1)
   t.deepEqual(image.out.args[0], ['-equalize'])
   t.end()
@@ -36,7 +36,7 @@ tape('single argument with no values', t => {
 tape('single argument with one value', t => {
   t.plan(2)
   const image = gm()
-  gmargs.apply(image, ['-modulate 120'])
+  gmagick.addRawArgs(image, ['-modulate 120'])
   t.equal(image.out.callCount, 1)
   t.deepEqual(image.out.args[0], ['-modulate', '120'])
   t.end()
@@ -45,7 +45,7 @@ tape('single argument with one value', t => {
 tape('single argument with space-separated values', t => {
   t.plan(2)
   const image = gm()
-  gmargs.apply(image, ['-unsharp 2 0.5 0.5 0'])
+  gmagick.addRawArgs(image, ['-unsharp 2 0.5 0.5 0'])
   t.equal(image.out.callCount, 1)
   t.deepEqual(image.out.args[0], ['-unsharp', '2 0.5 0.5 0'])
   t.end()
@@ -54,7 +54,7 @@ tape('single argument with space-separated values', t => {
 tape('multiple arguments', t => {
   t.plan(2)
   const image = gm()
-  gmargs.apply(image, [
+  gmagick.addRawArgs(image, [
     '-equalize',
     '-modulate 120',
     '-unsharp 2 0.5 0.5 0'

test/diff.js → test/integration/diff.js

@@ -1,7 +1,7 @@
 const _ = require('lodash')
 const childProcess = require('child_process')
 const gm = require('gm')
-const convert = require('../lib/index')
+const convert = require('../../lib/index')
 
 // process an image, and compare to the expected output
 exports.image = function (test, args) {

test/video.js → test/integration/video.js

@@ -1,7 +1,7 @@
 const assert = require('assert')
 const tape = require('tape')
 const diff = require('./diff')
-const convert = require('../lib/index')
+const convert = require('../../lib/index')
 
 tape('can downsample a video for a smaller filesize', (test) => {
   diff.video(test, {

test/ffmpeg.js → test/video/ffmpeg.js

@@ -1,7 +1,7 @@
 const assert = require('assert')
 const tape = require('tape')
 const childProcess = require('child_process')
-const ffmpeg = require('../lib/ffmpeg')
+const ffmpeg = require('../../lib/video/ffmpeg')
 const mockSpawn = require('mock-spawn')
 const sinon = require('sinon')