The /audio/concat Robot

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

The /audio/concat Robot concatenates several audio files together.

Parameters

Name Type Default Description
use (required) String / Array of Strings

General

Specifies which Step(s) to use as the input to this Robot.

Special Step names

A special Step name is ":original", which provides user uploads handled by Transloadit.

Providing several Steps as input

You can add arrays to use several Steps:
"use": [
  ":original",
  "encoded",
  "resized"
]

Step bundling

Some Robots can gather several Step results for a single invocation. For example, the /file/compress Robot would normally create one Zip file for each file passed to it. If you'd set bundle_steps to true, however, it will create one archive containing all the result files from all Steps you give it. To enable bundling, provide an object like the one below to the use parameter:
  "use": {
    "steps": [
      ":original",
      "encoded",
      "resized"
    ],
    "bundle_steps": true
  }
This is a crucial parameter for the /video/adaptive Robot, otherwise you'll generate 1 playlist for each viewing quality.
Keep in mind that all input Steps must be present in your Template. If one of them is missing, no result is generated because the Robot waits indefinitely for all input Steps to be finished.

Group by original

Sticking with the /file/compress Robot example, you can set group_by_original to true, in order to create a separate Zip file for each of your uploaded or imported files, instead of creating one archive containing all originals (or one per resulting file). This is a crucial parameter for the /media/playlist Robot.

Demo

See a demo for the use parameter here.
preset String "mp3" Performs conversion using pre-configured settings. If you specify your own FFmpeg parameters using the Robot's ffmpeg parameter and you have not specified a preset, then the default mp3 preset is not applied. This is to prevent you from having to override each of the MP3 preset's values manually. For a list of audio presets, see audio presets.
bitrate Integer Auto Bit rate of the resulting audio file, in bits per second. If not specified will default to the bit rate of the input audio file
sample_rate Integer Auto Sample rate of the resulting audio file, in Hertz. If not specified will default to the sample rate of the input audio file

Demos

Our /audio/concat Robot can be used in combination with other Robots, to create powerful workflows unique to your use case. Here are a few example scenarios that you can try live on our website:

Blog posts about the /audio/concat Robot

We wrote the following posts about the /audio/concat Robot on our blog:

Did you know?

You can easily combine Robots to create powerful workflows, unique to your business.
This is the power of Transloadit.