# Mp3Info
The fastest PHP library to get mp3 tags&meta.

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This class extracts information from mpeg/mp3 audio:

| Audio        | id3v1 Tags | id3v2 Tags |
|--------------|------------|------------|
| duration     | song       | TIT2       |
| bitRate      | artist     | TPE1       |
| sampleRate   | album      | TALB       |
| channel      | year       | TYER       |
| framesCount  | comment    | COMM       |
| codecVersion | track      | TRCK       |
| layerVersion | genre      | TCON       |

1. Usage
2. Performance
3. Console scanner
4. API
	- Audio information
	- Object members
	- Static methods
4. Technical information

# Usage
After creating an instance of `Mp3Info` with passing filename as the first argument to the constructor, you can retrieve data from object properties (listed below).

If you need parse tags, you should set 2nd argument this way:

```php
use wapmorgan\Mp3Info\Mp3Info;
$audio = new Mp3Info($fileName, true);
// or omit 2nd argument to increase parsing speed
$audio = new Mp3Info($fileName);
```

And after that access object properties to get audio information:

```php
echo 'Audio duration: '.floor($audio->duration / 60).' min '.floor($audio->duration % 60).' sec'.PHP_EOL;
echo 'Audio bitrate: '.($audio->bitRate / 1000).' kb/s'.PHP_EOL;
// and so on ...
```

To access id3v1 tags use `$tags1` property:

```php
echo 'Song '.$audio->tags1['song'].' from '.$audio->tags1['artist'].PHP_EOL;
```

# Performance

* Typically it parses one mp3-file with size around 6-7 mb in less than 0.001 sec.
* List of 112 files with constant & variable bitRate with total duration 5:22:28 are parsed in 1.76 sec. *getId3* library against exactly the same mp3 list works for 8x-10x slower - 9.9 sec.
* If you want, there's a very easy way to compare. Just install `nass600/get-id3` package and run console scanner against any folder with audios. It will print time that Mp3Info spent and that getId3.


# Console scanner
To test Mp3Info you can use built-in script that scans dirs and analyzes all mp3-files inside them. To launch script against current folder:

```bash
php bin/scan ./
```

# API

### Audio information

| Property        | Description                                                        | Values                                                      |
|-----------------|--------------------------------------------------------------------|-------------------------------------------------------------|
| `$codecVersion` | MPEG codec version                                                 | 1 or 2                                                      |
| `$layerVersion` | Audio layer version                                                | 1 or 2 or 3                                                 |
| `$audioSize`    | Audio size in bytes. Note that this value is NOT equals file size. | *int*                                                       |
| `$duration`     | Audio duration in seconds.microseconds                             | like 3603.0171428571 (means 1 hour and 3 sec)               |
| `$bitRate`      | Audio bit rate in bps                                              | like 128000 (means 128kb/s)                                 |
| `$sampleRate`   | Audio sample rate in Hz                                            | like 44100 (means 44.1KHz)                                  |
| `$isVbr`        | Contains true if audio has variable bit rate                       | *boolean*                                                   |
| `$channel`      | Channel mode                                                       | `'stereo'` or `'dual_mono'` or `'joint_stereo'` or `'mono'` |

### Object members
- `float $_parsingTime`

	Contains time spent to read&extract audio information in *sec.msec*.

- `array $tags1`

	Audio tags ver. 1 (aka id3v1).

- `array $tags2`

	Audio tags ver. 2 (aka id3v2).

- `public function __construct($filename, $parseTags = false)`

	Creates new instance of object and initiate parsing. If second argument is *true*, audio tags will be parsed.

### Static methods

- `static public function isValidAudio($filename)`

	Checks if file `$filename` looks like an mp3-file. Returns **true** if file similar to mp3, otherwise false.

## Technical information
Supporting features:
* id3v1
* id3v2.3.0
* Variable Bit Rate (VBR)

Used sources:
* [mpeg header description](http://mpgedit.org/mpgedit/mpeg_format/mpeghdr.htm)
* [id3v2 tag specifications](http://id3.org/Developer%20Information). Сoncretely: [id3v2.3.0](http://id3.org/id3v2.3.0), [id3v2.2.0](http://id3.org/id3v2-00), [id3v2.4.0](http://id3.org/id3v2.4.0-changes)
* [Xing, Info and Lame tags specifications](http://gabriel.mp3-tech.org/mp3infotag.html)