silid / transcode-to-mp3-stream

Php library for streaming various audio files as mp3 by transcoding on the fly

Transcode to MP3 Stream PHP Library

Transcode, on the fly, any media file that ffmpeg can read into an MP3 stream playable natively by any modern browser. The library handles the annoying requirements of generating the correct headers and relies on ffmpeg to handle the actual transcoding.

Useful for cases where you have a large collection of audio files which you want users to be able to stream, but don't wish to transcode them all in advance.

Works well with HTML5/JS audio players such as audio.js.

Status

Beta. This package is working, but may still have some kinks to workout.

Dependencies

We require shell access to ffmpeg with the lame codec for mp3 encoding. We also require a newish version of ffprobe (which comes with ffmpeg). However, the current version of in the Ubuntu repository is not modern enough. I'll update with more on that later.

On Ubuntu, these packages do the trick for me:

sudo apt-get install ffmpeg
sudo apt-get install libavcodec-extra-53

Installation

Add this line to your composer.json file's "require" section:

"captbaritone/transcode-to-mp3-stream": "dev-master"

Then issue at the command line, in your projects directory:

composer update

Usage

I'm assuming, you have the package installed via composer.

The only method you should need is output() on the Mp3Stream object. It takes the following arguments, of which only the first is required:

• $sourceMedia Path to the file you wish to transcode
• $outputFilename The filename for the transcoded output
• $kbps The constant bitrate bits per second to encode the output with
• $start The point in the source where we want to start (in seconds)
• $end The point in the source where we want to stop (in seconds)

Simple usage:

<?php

use Captbaritone\TranscodeToMp3Stream\Mp3Stream;

$mp3Stream = new Mp3Stream();
$mp3Stream->output('example.flac');

Example

See example.php for an example of how the script can be used.

If you have a new enough version of PHP, you could test it by issuing this in your terminal...

cd /path/to/transcode-to-mp3-stream
php -S localhost:9000 example.php

...and then opening http://localhost:8000 in your browser.

Testing

Assuming you have both composer and phpunit install globally:

git clone [email protected]:captbaritone/transcode-to-mp3-stream.git
cd transcode-to-mp3-stream
composer --dev install
phpunit

Help/questions

If you have any questions, or get stuck please let me know: [email protected].

License

This project is released under the MIT License. The example audio file is an excerpt from a Creative Commons recording of J.S. Bach's Goldberg Variations. You can find the whole recording, and more information at the Open Goldberg Variations website.