Fade-in and out multiple times within the same audio file

In this demo, we are going to look at how you can fade in and out audio multiple times within the same audio file. If you are familiar with our other demos, you will have noticed that we have a demo that covers the idea of fading in and out audio so you may wonder why we are showing this again. Well, the thing is FFmpeg's fade-out effect sets the audio volume to equal 0 for the remainder of a file, meaning if a user wishes to use a following fade-in after the initial fade-out, FFmpeg will have nowhere to go as the volume of the file has been set to 0.

So we can get around this we're going to discuss the concept of timeline editing. Timeline editing allows us to set expressions that are evaluated before effects are applied to our files. And well under our given circumstance, this means we have a method which will allow us to create our desired effect. Notice how we use =enable='between(t, 0, 15)' at the beginning of our af statement. This means that the afade effect for fading in is only applied to the first 15 seconds of the audio. We repeat this method to apply a fade-out which is only applied to the following 15 seconds, before again repeating the effect throughout our file. Finally, we use FFmpeg's to parameter to set the total file's track length to 70 seconds.

Step 1:

Handle uploads

We can handle uploads of your users directly.Learn more

joakim_karud-rock_angel.mp3

Audio – 8.9 MB

233s

":original": {
  "robot": "/upload/handle"
}

/upload/handle

This bot receives uploads that your users throw at you from browser or apps, or that you throw at us programmatically

Step 2:

Encode audio

We offer a variety of features to reduce audio size while maintaining quality, as well as add effects like loops or watermarks.Learn more

joakim_karud-rock_angel.mp3

Audio – 1.1 MB

70s

"encode_audio": {
  "use": ":original",
  "robot": "/audio/encode",
  "result": true,
  "ffmpeg": {
    "af": "afade=enable='between(t,0,15)':t=in:ss=0:d=6, afade=enable='between(t,15,30)':t=out:st=15:d=6,afade=enable='between(t,30,60)':t=in:st=30:d=6, afade=t=out:st=60:d=6",
    "to": "70"
  },
  "ffmpeg_stack": "v7",
  "preset": "mp3"
}

/audio/encode

This bot converts audio files into all kinds of formats for you. We provide encoding presets for the most common formats

Step 3:

Export files to Amazon S3

We export to the storage platform of your choice.Learn more

:original

https://demos.transloadit.com/37/51babf3b2e4b4c9ce32af19f594d8a/joakim_karud-rock_angel.mp3

encode_audio

https://demos.transloadit.com/2f/e95c01318b4c139203ded344f2de65/joakim_karud-rock_angel.mp3

"exported": {
  "use": [
    "encode_audio",
    ":original"
  ],
  "robot": "/s3/store",
  "credentials": "demo_s3_credentials",
  "url_prefix": "https://demos.transloadit.com/"
}

/s3/store

This bot exports encoding results to Amazon S3

Live Demo. See for yourself

Loading Uppy demo…

This live demo is powered by Uppy, our open source file uploader that you can also use without Transloadit, and tus, our open protocol for resumable file uploads that is making uploading more reliable across the world.

Build this in your own language

<!-- This pulls Uppy from our CDN -->
<!-- For smaller self-hosted bundles, install Uppy and plugins manually: -->
<!-- npm i --save @uppy/core @uppy/dashboard @uppy/remote-sources @uppy/transloadit ... -->
<link
  href="https://releases.transloadit.com/uppy/v3.10.0/uppy.min.css"
  rel="stylesheet"
/>
<button id="browse">Select Files</button>
<script type="module">
  import {
    Uppy,
    Dashboard,
    ImageEditor,
    RemoteSources,
    Transloadit,
  } from 'https://releases.transloadit.com/uppy/v3.10.0/uppy.min.mjs'
  const uppy = new Uppy()
    .use(Transloadit, {
      waitForEncoding: true,
      alwaysRunAssembly: true,
      assemblyOptions: {
        params: {
          // It's often better store encoding instructions in your account
          // and use a `template_id` instead of adding these steps inline
          steps: {
            ':original': {
              robot: '/upload/handle',
            },
            encode_audio: {
              use: ':original',
              robot: '/audio/encode',
              result: true,
              ffmpeg: {
                af: 'afade=enable='between(t,0,15)':t=in:ss=0:d=6, afade=enable='between(t,15,30)':t=out:st=15:d=6,afade=enable='between(t,30,60)':t=in:st=30:d=6, afade=t=out:st=60:d=6',
                to: '70',
              },
              ffmpeg_stack: 'v7',
              preset: 'mp3',
            },
            exported: {
              use: ['encode_audio', ':original'],
              robot: '/s3/store',
              credentials: 'demo_s3_credentials',
              url_prefix: 'https://demos.transloadit.com/',
            },
          },
        },
      },
    })
    .use(Dashboard, { trigger: '#browse' })
    .use(ImageEditor, { target: Dashboard })
    .use(RemoteSources, {
      companionUrl: 'https://api2.transloadit.com/companion',
    })
    .on('complete', ({ transloadit }) => {
      // Due to `waitForEncoding:true` this is fired after encoding is done.
      // Alternatively, set `waitForEncoding` to `false` and provide a `notify_url`
      console.log(transloadit) // Array of Assembly Statuses
      for (const assembly of transloadit) {
        console.log(assembly.results) // Array of all encoding results
      }
    })
    .on('error', (error) => {
      console.error(error)
    })
</script>

Read docs: Browsers

So many ways to integrate

Transloadit is a service for companies with developers. And there are many ways developers can put Transloadit to good use inside your company to automate media processing.