feat(28): Add write-stream output support (#36)

* Update @ScottyFillups as a contributor

* Add @cmd430 as a contributor

* Add write-stream output support

* Add null output support

.all-contributorsrc

@@ -15,7 +15,19 @@
       "avatar_url": "https://avatars2.githubusercontent.com/u/18666879?v=4",
       "profile": "http://scottyfillups.io",
       "contributions": [
-        "doc"
+        "doc",
+        "code",
+        "design"
+      ]
+    },
+    {
+      "login": "cmd430",
+      "name": "cmd430",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/2668906?v=4",
+      "profile": "https://github.com/cmd430",
+      "contributions": [
+        "code",
+        "ideas"
       ]
     }
   ]

README.md

@@ -1,5 +1,5 @@
 # simple-thumbnail 
-[![All Contributors](https://img.shields.io/badge/all_contributors-1-orange.svg?style=rounded)](#contributors)
+[![All Contributors](https://img.shields.io/badge/all_contributors-2-orange.svg?style=rounded)](#contributors)
 [![npm version](https://badge.fury.io/js/simple-thumbnail.svg)](https://badge.fury.io/js/simple-thumbnail)
 [![Build Status](https://travis-ci.org/ScottyFillups/simple-thumbnail.svg?branch=master)](https://travis-ci.org/ScottyFillups/simple-thumbnail)
 [![Coverage Status](https://coveralls.io/repos/github/ScottyFillups/simple-thumbnail/badge.svg?branch=master)](https://coveralls.io/github/ScottyFillups/simple-thumbnail?branch=master)
@@ -34,6 +34,13 @@ async function run () {
 }
 
 run()
+
+// genThumbnail also supports piping to write streams, so you can do this with Express!
+app.get('/some/endpoint', (req, res) => {
+  genThumbnail('path/to/video.webm', res, '150x100')
+    .then(() => console.log('done!'))
+    .catch(err => console.error(err))
+})
 ```
 
 ## Getting FFmpeg
@@ -69,9 +76,9 @@ The URL, file path, or read-stream of an image or video.
 
 #### output
 
-Type: `String`
+Type: `String | stream.Writable | Null`
 
-The file path of the generated thumbnail, assumes directories exist.
+The file path of the generated thumbnail, a write-stream, or null. If null, `genThumbnail` will resolve to a read-stream that you can pipe somewhere. If you're specifying a file path, make sure the directories exist.
 
 #### size
 
@@ -106,8 +113,12 @@ Seeks the video to the provided time. The time must be in the following form: `h
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 <!-- prettier-ignore -->
-| [<img src="https://avatars2.githubusercontent.com/u/18666879?v=4" width="100px;"/><br /><sub><b>Philip Scott</b></sub>](http://scottyfillups.io)<br />[📖](https://github.com/ScottyFillups/simple-thumbnail/commits?author=ScottyFillups "Documentation") |
-| :---: |
+| [<img src="https://avatars2.githubusercontent.com/u/18666879?v=4" width="100px;"/><br /><sub><b>Philip Scott</b></sub>](http://scottyfillups.io)<br />[📖](https://github.com/ScottyFillups/simple-thumbnail/commits?author=ScottyFillups "Documentation") [💻](https://github.com/ScottyFillups/simple-thumbnail/commits?author=ScottyFillups "Code") [🎨](#design-ScottyFillups "Design") | [<img src="https://avatars1.githubusercontent.com/u/2668906?v=4" width="100px;"/><br /><sub><b>cmd430</b></sub>](https://github.com/cmd430)<br />[💻](https://github.com/ScottyFillups/simple-thumbnail/commits?author=cmd430 "Code") [🤔](#ideas-cmd430 "Ideas, Planning, & Feedback") |
+| :---: | :---: |
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 <!-- ALL-CONTRIBUTORS-LIST: START - Do not remove or modify this section -->
 <!-- ALL-CONTRIBUTORS-LIST:END -->
+
+This project follows the [all-contributors](https://github.com/kentcdodds/all-contributors) specification.
+
+Contributions of any kind are welcome!

index.js

@@ -63,19 +63,24 @@ function buildArgs (input, output, { width, height, percentage }, seek) {
 /**
  * Spawn an instance of ffmpeg and generate a thumbnail
  * @func    ffmpegExecute
- * @param   {String}          path   The path of the ffmpeg binary
- * @param   {Array<string>}   args   An array of arguments for ffmpeg
- * @param   {stream.Readable} stream A readable stream to pipe data to
- *                                   the standard input of ffmpeg
+ * @param   {String}          path      The path of the ffmpeg binary
+ * @param   {Array<string>}   args      An array of arguments for ffmpeg
+ * @param   {stream.Readable} [rstream] A readable stream to pipe data to
+ *                                      the standard input of ffmpeg
+ * @param   {stream.Writable} [wstream] A writable stream to receive data from
+ *                                      the standard output of ffmpeg
  * @returns {Promise}  Promise that resolves once thumbnail is generated
  */
-function ffmpegExecute (path, args, stream = null) {
+function ffmpegExecute (path, args, rstream, wstream) {
   const ffmpeg = spawn(path, args, { shell: true })
   let stderr = ''
 
   return new Promise((resolve, reject) => {
-    if (stream) {
-      stream.pipe(ffmpeg.stdin)
+    if (rstream) {
+      rstream.pipe(ffmpeg.stdin)
+    }
+    if (wstream) {
+      ffmpeg.stdout.pipe(wstream)
     }
 
     ffmpeg.stderr.on('data', (data) => {
@@ -84,23 +89,40 @@ function ffmpegExecute (path, args, stream = null) {
     ffmpeg.stderr.on('error', (err) => {
       reject(err)
     })
-
-    ffmpeg.on('close', resolve)
     ffmpeg.on('exit', (code, signal) => {
       if (code !== 0) {
         const err = new Error(`ffmpeg exited ${code}\nffmpeg stderr:\n\n${stderr}`)
-
         reject(err)
       }
     })
+    ffmpeg.on('close', resolve)
   })
 }
 
+/**
+ * Spawn an instance of ffmpeg and generate a thumbnail
+ * @func    ffmpegStreamExecute
+ * @param   {String}          path      The path of the ffmpeg binary
+ * @param   {Array<string>}   args      An array of arguments for ffmpeg
+ * @param   {stream.Readable} [rstream] A readable stream to pipe data to
+ *                                      the standard input of ffmpeg
+ * @returns {Promise}  Promise that resolves to ffmpeg stdout
+ */
+function ffmpegStreamExecute (path, args, rstream) {
+  const ffmpeg = spawn(path, args, { shell: true })
+
+  if (rstream) {
+    rstream.pipe(ffmpeg.stdin)
+  }
+
+  return Promise.resolve(ffmpeg.stdout)
+}
+
 /**
  * Generates a thumbnail from the first frame of a video file
  * @func    genThumbnail
- * @param   {String|stream.Readable} input      Path to video, or a read stream
- * @param   {String}  output                    Output path of the thumbnail
+ * @param   {String|stream.Readable}   input    Path to video, or a read stream
+ * @param   {String|stream.Writeable}  output   Output path of the thumbnail
  * @param   {String}  size         The size of the thumbnail, eg. '240x240'
  * @param   {Object}  [config={}]  A configuration object
  * @param   {String}  [config.path='ffmpeg']    Path of the ffmpeg binary
@@ -110,18 +132,22 @@ function ffmpegExecute (path, args, stream = null) {
 function genThumbnail (input, output, size, config = {}) {
   const ffmpegPath = config.path || process.env.FFMPEG_PATH || 'ffmpeg'
   const seek = config.seek || '00:00:00'
+  const rstream = typeof input === 'string' ? null : input
+  const wstream = typeof output === 'string' ? null : output
 
   const parsedSize = parseSize(size)
   const args = buildArgs(
     typeof input === 'string' ? input : 'pipe:0',
-    output,
+    typeof output === 'string' ? output : '-f singlejpeg pipe:1',
     parsedSize,
     seek
   )
 
-  return typeof input === 'string'
-    ? ffmpegExecute(ffmpegPath, args)
-    : ffmpegExecute(ffmpegPath, args, input)
+  if (output === null) {
+    return ffmpegStreamExecute(ffmpegPath, args, rstream)
+  }
+
+  return ffmpegExecute(ffmpegPath, args, rstream, wstream)
 }
 
 module.exports = genThumbnail