PHP-Reader Documentation: Zend_Media_Flac Class

By svollbehr

Introduction

The Zend_Media_Flac class provides a partial implementation of the Free Lossless Audio Codec (FLAC) format.

FLAC is an audio format similar to MP3, but lossless, meaning that audio is compressed in FLAC without any loss in quality. This is similar to how Zip works, except with FLAC you will get much better compression because it is designed specifically for audio, and you can play back compressed FLAC files in your favorite player (or your car or home stereo) just like you would an MP3 file.

FLAC stands out as the fastest and most widely supported lossless audio codec, and the only one that at once is non-proprietary, is unencumbered by patents, has an open-source reference implementation, has a well documented format and API, and has several other independent implementations.

The class is capable of only reading metadata blocks. The class is unable to read or decode the audio data frames. You may, however, implement this functionality on top of what this class provides.

Class Information

• Documentation location: <package>/docs/ or online here
• Source location: <package>/src/Zend/Media/Flac.php
• Requirements:
• <package>/src/Zend/Io package
• <package>/src/Zend/Bit package
• <package>/src/Zend/Media/Flac/Exception.php
• <package>/src/Zend/Media/Flac/MetadataBlock.php
• <package>/src/Zend/Media/Flac/MetadataBlock/ folder
• <package>/src/Zend/Media/Vorbis/Header/Comment.php

• Issues

Metadata Blocks

FLAC supports up to 128 kinds of metadata blocks; currently the following are defined and supported by this class.

Examples

Example #1: How to read FLAC file information

The most common reason to use the Zend_Media_Flac class is probably to extract information from the metadata blocks of an FLAC file, or in particular VorbisComment and Picture metadata blocks. Below is a quick sample how to get you started.

<?php
require_once 'Zend/Media/Flac.php'; // or using autoload

$flac = new Zend_Media_Flac("file.flac");

// Extract picture
if ($flac->hasMetadataBlock(Zend_Media_Flac::PICTURE)) {
    header('Content-Type: ' . $flac->getPicture()->getMimeType());
    echo $flac->getPicture()->getData();
}

// Extract song information
$title = $flac->getVorbisComment()->getTitle();    // contains the first song title
$artist = $flac->getVorbisComment()->getArtist();  // contains the first song artist
$vendor = $flac->getVorbisComment()->getVendor();  // contains the software information

// Extract file information
$sampleRate = $flac->getStreaminfo()->getSampleRate();

Zend_Media_Flac uses the same class for reading the Vorbis Comments as the Zend_Media_Vorbis class does. Hence, please see the Zend_Media_Vorbis class documentation for more about how to read Vorbis Comments.

As already so familiar from the Zend_Media_Id3v1 and Zend_Media_Id3v2 classes, the Zend_Media_Flac class also supports shorthands for accessing metadata blocks and their fields. The above code could also be written as shown below.

<?php
require_once 'Zend/Media/Flac.php'; // or using autoload

$flac = new Zend_Media_Flac("file.flac");

// Extract picture
if ($flac->hasMetadataBlock(Zend_Media_Flac::PICTURE)) {
    header('Content-Type: ' . $flac->picture->mimeType);
    echo $flac->picture->data;
}

// Extract song information
$title = $flac->vorbisComment->title;    // contains the first song title
$artist = $flac->vorbisComment->artist;  // contains the first song artist
$vendor = $flac->vorbisComment->vendor;  // contains the software information

// Extract file information
$sampleRate = $flac->streaminfo->sampleRate; // e.g. 44100Hz

Further Reading

See the class documentation found in the source package for the documentation for all the classes and their methods.

Also, leave a comment if you come up with an idea for an example that would be nice to have added here!