Caption And Subtitle Converter for PHP

>> live demo <<

🥳🎉👏 Probably the best subtitle parser 🥳🎉👏

💣 Tested on thousands of user submitted files 🤯
🔥 Almost 100% unit test coverage 💥

Supported formats

Format	Extension	Internal format name
SubRip	.srt	srt
WebVTT	.vtt	vtt
Scenarist	.scc	scc
EBU STL (only reader)	.stl	ebu_stl
Spruce Technologies SubTitles	.stl	stl
Youtube Subtitles	.sbv	sbv
SubViewer	.sub	sub_subviewer
MicroDVD	.sub	sub_microdvd
Advanced Sub Station	.ass	ass
Netflix Timed Text	.dfxp	dfxp
TTML	.ttml	ttml
SAMI	.smi	smi
QuickTime	.qt.txt	txt_quicktime
Rich text format (only reader)	.rtf	rtf
DOCX (only reader)	.docx	docx
LyRiCs	.lrc	lrc
Comma separated values	.csv	csv
Plaintext	.txt	txt

Command line

Can be used from the command line to convert from .srt to .vtt

php subtitles.phar input.srt output.vtt

subtitles.phar file can be found here - https://github.com/mantas-done/subtitles/releases

Installation (supports PHP 7.4...8.4)

composer require mantas-done/subtitles

Usage

Convert .srt file to .vtt:

// add namespace
use \Done\Subtitles\Subtitles;

Subtitles::convert('subtitles.srt', 'subtitles.vtt');

// if no input format is specified, library will determine file format by its content
// if third parameter is specified, library will convert the file to specified format.
// list of formats are in Subtitle::$formats, they are: ass, dfxp, sbv, srt, stl, sub, ttml, txt_quicktime, vtt 
Subtitles::convert('subtitles1', 'subtitles2', ['output_format' => 'vtt']); 

Manually create file

$subtitles = new Subtitles();
$subtitles->add(0, 5, 'This text is shown in the beggining of video for 5 seconds');
$subtitles->save('subtitles.vtt');

Load subtitles from existing file

$subtitles = Subtitles::loadFromFile('subtitles.srt');

Load subtitles from string

$string = "
1
00:02:17,440 --> 00:02:20,375
Senator, we're making our final approach
";  

$subtitles = Subtitles::loadFromString($string);

Save subtitles to file

$subtitles->save('subtitler.vtt');

Get file content without saving to file

echo $subtitles->content('vtt');

Add subtitles

$subtitles->add(0, 5, 'some text'); // from 0, till 5 seconds  

// Add multiline text
$subtitles->add(0, 5, [
    'first line',
    'second line',
]);

// Add styles to VTT file format
// Only VTT supports styles currently
$subtitles->add(0, 5, 'text', ['vtt_cue_settings' => 'position:50% line:15% align:middle']);

Remove subtitles

$subtitles->remove(0, 5); // from 0, till 5 seconds

Trim subtitles

$subtitles->trim(3, 4); // get only from 3, till 4 seconds

Add 1 second to all subtitles

$subtitles->shiftTime(1);

Subtract 0.5 second

$subtitles->shiftTime(-0.5);

Add 5 second to subtitles starting from 1 minute till 2 mintes

$subtitles->shiftTime(5, 60, 120);

Example: shift time gradually by 2 seconds over 1 hour video. At the beginning of the video don't change time, in the middle shift time by 1 second. By the end of video, shift time by 2 seconds.

$subtitles->shiftTimeGradually(2, 0, 3600);

Exceptions

Library will throw UserException, it's message can be shown to the user.

try {
    (new \Done\Subtitles\Subtitles())->add(0, 1, 'very long text... aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa')->content('scc');
} catch (\Done\Subtitles\Code\UserException $e) {
    echo $e->getMessage(); // SCC file can't have more than 4 lines of text each 32 characters long. This text is too long: <text from user file that triggered this error>
}

By default, library tries to detect different file errors that can be shown to the user, so he would be able to fix them. If you want to relax the rules and allow the library to convert even somewhat invalid files, use ['strict' => false]

Subtitles::convert($input, $output, ['strict' => false]);
Subtitles::loadFromString($string, ['strict' => false]);
Subtitles::loadFromFile($input, ['strict' => false]);

How to add new subtitle format?

You need to implement ConverterContract.php interface. It has two methods.

fileContentToInternalFormat($file_content)  
  
internalFormatToFileContent($internal_format)

Basically what your implementation should be able to do, is convert subtitle file to "internal library's format", and from internal library's format back to subtitle file.

"Internal library's" format is used like middle ground, to be able to convert between different formats.

Best example is to look how SrtConverter.php is implemented.
And this is example of .srt file.

Registering your converter

Subtitles::registerConverter(FakeDocxConverter::class, 'docx_fake', 'docx', 'Fake docx converter');

You can add a new converter or replace the existing one if the format name is the same (the second parameter).

"Internal Format"

"Internal Format" is just a PHP array. It is used internally in library to be able to convert between different formats.

Array
(
    [0] => Array
        (
            [start] => 137.44
            [end] => 140.375
            [lines] => Array
                (
                    [0] => Senator, we're making
                    [1] => our final approach into Coruscant.
                )
        )
    [1] => Array
        (
            [start] => 140.476
            [end] => 142.501
            [lines] => Array
                (
                    [0] => Very good, Lieutenant.
                )
        )
)

[start] - when to start showing text (float - seconds)
[end] - when to stop showing text (float -seconds)
[lines] - one or more text lines (array)

Running Tests

php vendor/bin/phpunit

Contribution

You can contribute in any way you want. If you need some guidance, choose something from this table:

Task	Difficulty	Description
Add new formats	Medium	Supporting more formats is nice. Some popular formats: .mcc, .cap
Refactor StlConverter.php file	Easy	.stl format is very similar to .srt. The only problem is that StlConverter.php code can be simplified a lot (check SrtConverter.php as example)
Add .scc format	Hard	Format description

For now library should support only basic features (several lines of text). No need to support different text styles or positioning of text.

Report Bugs

If some file is not working with the library, please create and issue and attach the file.