We are a Swiss Army knife for your files
Transloadit is a service for companies with developers. We handle their file uploads and media processing. This means that they can save on development time and the heavy machinery that is required to handle big volumes in an automated way.
We pioneered with this concept in 2009 and have made our customers happy ever since. We are still actively improving our service in 2026, as well as our open source projects uppy.io and tus.io, which are changing how the world does file uploading.
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
":original": {
"robot": "/upload/handle"
}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
"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"
}Step 3:
Export files to Amazon S3
We export to the storage platform of your choice.Learn more
"exported": {
"use": [
"encode_audio",
":original"
],
"robot": "/s3/store",
"credentials": "demo_s3_credentials",
"url_prefix": "https://demos.transloadit.com/"
}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>
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.
Bulk imports
Add one of our import Robots to acquire and transcode massive media libraries.
Handling uploads
We are the experts at reliably handling uploads. We wrote the protocol for it.
Front-end integration
We integrate with web browsers via our next-gen file uploader Uppy and SDKs for Android and iOS.
Back-end integration
Send us batch jobs in any server language using one of our SDKs or directly interfacing with our REST API.
Pingbacks
Configure a notify_url to let your server receive transcoding results JSON in the transloadit POST field.
On-demand
Use our Smart CDN to adapt files on-demand and stream them directly to your users.
Audio encoding
Document processing