Convert an Audio File to Another Format With Go and FFMpeg

Prerequisites/Requirements

To run the code, you will need the following:

• Go 1.22 or above
• Docker Desktop (if you want to use the project's Docker Compose configuration)
• A network testing tool such as curl or Postman
• FFMpeg globally installed with [libfdk_aa][ffmpeg_libfdk_aac_docs_url], flac, and [libmp3lame][ffmpeg_libmp3lame_docs_url] encoding support. See the [FFMpeg compilation documentation][ffmpeg_compiling_docs_url] for details on how to enable them.

Application Overview

This is a small Go application that shows how to convert audio files to a limited number of other audio file formats. The application supports an upcoming tutorial on the Twilio blog.

The app's has a single route, that supports POST requests, and is defined as: /convert/{to_format}. {to_format} can be one of aac, flac, or mp3 as the project, currently, only supports converting to AAC, FLAC, and MP3 formats.

The route looks for an audio file in the POST request data, in a variable named audio_file. If found, it converts it to the format specified by {to_format}.

Note: the uploaded audio must be in a format supported by your FFMpeg installation. To view the list of supported formats, run the following command:

ffmpeg -formats

How to use the application

Start the application

To run the project, you can either use Composer or the included Docker Compose configuration.

# Start the project with Composer
composer serve

# Start the project with Docker Compose
docker compose up -d

Convert an audio file

Once up and running, use a network testing tool such as curl or Postman to make a POST request to the default route.

Convert an audio file using Curl

To convert an audio file using curl, use the example below, using curl:

curl \
  --form "audio_file=@resources/audio/sample.mp3" \
  --output sample.flac \
  http://localhost:8080/convert/flac

The example above posts the sample MP3 file that accompanies the project, converting it to FLAC format.

Convert an audio file using Postman

Alternatively, you could use Postman, if you prefer a GUI.

Set the request type to POST. Then, under Body, set the request type to form-data. After that, add a key named audio_file, set its type to File, then chose sample.mp3 file in the resources/audio directory, or use an audio file of your choice. Finally, click Send to make the request.

If the request is successful, you'll see an audio control in the response's body section, which you can then listen to and confirm that the file has been successfully converted.

The sample audio file was created by Lidérc from Pixabay.

[ffmpeg_flac_docs_url]: [ffmpeg_libfdk_aac_docs_url]: https://trac.ffmpeg.org/wiki/Encode/AAC [ffmpeg_libmp3lame_docs_url]: https://trac.ffmpeg.org/wiki/Encode/MP3 [ffmpeg_compiling_docs_url]: https://trac.ffmpeg.org/wiki/CompilationGuide