Add read support for FLAC metadata blocks

git-svn-id: http://php-reader.googlecode.com/svn/trunk@241 51a70ab9-7547-0410-9469-37e369ee0574
2011-06-11 16:46:52 +00:00
parent 0d792cf221
commit 8bdcf4209a
12 changed files with 1431 additions and 12 deletions
--- a/src/Zend/Media/Flac/MetadataBlock/Seektable.php
+++ b/src/Zend/Media/Flac/MetadataBlock/Seektable.php
@@ -0,0 +1,82 @@
+<?php
+/**
+ * Zend Framework
+ *
+ * LICENSE
+ *
+ * This source file is subject to the new BSD license that is bundled
+ * with this package in the file LICENSE.txt.
+ * It is also available through the world-wide-web at this URL:
+ * http://framework.zend.com/license/new-bsd
+ * If you did not receive a copy of the license and are unable to
+ * obtain it through the world-wide-web, please send an email
+ * to license@zend.com so we can send you a copy immediately.
+ *
+ * @category   Zend
+ * @package    Zend_Media
+ * @subpackage FLAC
+ * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ * @version    $Id$
+ */
+
+/**#@+ @ignore */
+require_once 'Zend/Media/Flac/MetadataBlock.php';
+/**#@-*/
+
+/**
+ * This class represents the seektable metadata block. This is an optional block for storing seek points. It is possible
+ * to seek to any given sample in a FLAC stream without a seek table, but the delay can be unpredictable since the
+ * bitrate may vary widely within a stream. By adding seek points to a stream, this delay can be significantly reduced.
+ * Each seek point takes 18 bytes, so 1% resolution within a stream adds less than 2k. There can be only one SEEKTABLE
+ * in a stream, but the table can have any number of seek points. There is also a special 'placeholder' seekpoint which
+ * will be ignored by decoders but which can be used to reserve space for future seek point insertion.
+ *
+ * @category   Zend
+ * @package    Zend_Media
+ * @subpackage FLAC
+ * @author     Sven Vollbehr <sven@vollbehr.eu>
+ * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ * @version    $Id$
+ */
+final class Zend_Media_Flac_MetadataBlock_Seektable extends Zend_Media_Flac_MetadataBlock
+{
+    /** @var Array */
+    private $_seekpoints = array();
+
+    /**
+     * Constructs the class with given parameters and parses object related data.
+     *
+     * @param Zend_Io_Reader $reader The reader object.
+     */
+    public function __construct($reader)
+    {
+        parent::__construct($reader);
+
+        $seekpointCount = $this->getSize() / 18;
+        for ($i = 0; $i < $seekpointCount; $i++) {
+            $this->_seekpoints[] = array(
+                'sampleNumber'    => $this->_reader->readInt64BE(),
+                'offset'          => $this->_reader->readInt64BE(),
+                'numberOfSamples' => $this->_reader->readUInt16BE()
+            );
+        }
+    }
+    
+    /**
+     * Returns the seekpoint table. The array consists of items having three keys.
+     *
+     *   o sampleNumber    --  Sample number of first sample in the target frame, or 0xFFFFFFFFFFFFFFFF for a
+     *                         placeholder point.
+     *   o offset          --  Offset (in bytes) from the first byte of the first frame header to the first byte of the
+     *                         target frame's header.
+     *   o numberOfSamples --  Number of samples in the target frame.
+     *
+     * @return Array
+     */
+    public function getSeekpoints()
+    {
+        return $this->_seekpoints;
+    }
+}