php-ffmpeg concat audio filter - an incredibly simple filter to concat multiple audio files together. Should be easily tweaked to allow for videos too.

ConcatAudioFilter.php

<?php

use FFMpeg\Media\Audio;
use FFMpeg\Format\AudioInterface;
use FFMpeg\Filters\Audio\AudioFilterInterface;

class ConcatAudioFilter implements AudioFilterInterface
{
    private $files;
    private $priority;

    public function __construct(array $files = [], $priority = 0)
    {
        $this->files = $files;
        $this->priority = $priority;
    }

    /**
     * {@inheritdoc}
     */
    public function getPriority()
    {
        return $this->priority;
    }

    public function addFile($file)
    {
        $this->files[] = $file;

        return $this;
    }

    public function addFiles(array $files)
    {
        foreach ($files as $file) {
            $this->addFile($file);
        }

        return $this;
    }

    public function deleteFile($fileToDelete)
    {
        $this->files = array_values(array_filter($this->files, function($file) use ($fileToDelete) {
            return $fileToDelete !== $file;
        }));
    }

    /**
     * {@inheritdoc}
     */
    public function apply(Audio $audio, AudioInterface $format)
    {
        $params = [];
        $count = count($this->files) + 1;

        foreach ($this->files as $i => $file) {
            $params[] = '-i';
            $params[] = $file;
        }

        $params[] = '-filter_complex';
        $params[] = 'concat=n='.$count.':v=0:a=1 [a]';
        $params[] = '-map';
        $params[] = '[a]';

        return $params;
    }
}

usage.php

<?php

$ffmpeg = FFMpeg\FFMpeg::create();
$audio = $ffmpeg->open('file1.mp3');

$filter = new ConcatAudioFilter();
$filter->addFiles([
    'file_to_append1.mp3',
    'file_to_append2.mp3'
]);

$format = new FFMpeg\Format\Audio\Mp3();
$audio->addFilter($filter);
$audio->save($format, 'output.mp3');

Hi 😄
I tried to tweak this filter to apply to video but I doesn't work. It says
Class 'ConcatVideoFilter' not found
I edited your code and put the file in the video filters folder, as shown here: http://imgur.com/9olFY5T

What am I doing wrong?

EDIT: Same thing happens if I don't change your code at all and put the file in the audio filters folder.

EDIT2: I made it. A few bit changes in the code and I was able to apply your code to concatenate two video files. Forked.

The best!
Thank you!

Any idea how to show progress? =)

Hey @guivazcabral, would it mind you to help me with that, i'm trying too, to concatenate videos :/
Thanks !