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.


Name Type Default Description
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

Live 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, and the required Assembly Instructions to implement them.
You can also try demos of these examples right here, live on our website.

Concatenate two audio files

  "steps": {
    ":original": {
      "robot": "/upload/handle"
    "imported_postroll": {
      "robot": "/http/import",
      "url": ""
    "concatenated": {
      "use": {"steps":[{"name":":original", "fields":"file", "as":"audio_1"},{"name":"imported_postroll", "as":"audio_2"}]},
      "robot": "/audio/concat",
      "result": true,
      "ffmpeg_stack": "v3.3.3"
    "exported": {
      "use": ["imported_postroll", "concatenated", ":original"],
      "robot": "/s3/store",
      "credentials": "demo_s3_credentials",
      "path": "${unique_prefix}/both-anthems.${file.ext}"

Blog posts about our /audio/concat Robot

Over the years, we wrote the following posts about our /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.