Add amr

README.md

@@ -18,6 +18,7 @@ Supported formats:
   - aac
   - ogg
   - mp3
+  - amr
 
 How to use:
 

src/AmrAdapter.php

@@ -0,0 +1,93 @@
+<?php
+namespace wapmorgan\MediaFile;
+
+use Exception;
+use wapmorgan\BinaryStream\BinaryStream;
+
+/**
+ * Based on information from http://hackipedia.org/File%20formats/Containers/AMR,%20Adaptive%20MultiRate/AMR%20format.pdf
+ */
+class AmrAdapter implements AudioAdapter {
+    protected $filename;
+    protected $stream;
+    protected $bitrates;
+    protected $length;
+
+    static protected $modes = array(
+        0 => 4750,
+        1 => 5150,
+        2 => 5900,
+        3 => 6700,
+        4 => 7400,
+        5 => 7950,
+        6 => 10200,
+        7 => 12200,
+    );
+
+    static protected $frameSizes = array(
+        0 => 13,
+        1 => 14,
+        2 => 16,
+        3 => 18,
+        4 => 20,
+        5 => 21,
+        6 => 27,
+        7 => 32,
+    );
+
+    public function __construct($filename) {
+        if (!file_exists($filename) || !is_readable($filename)) throw new Exception('File "'.$filename.'" is not available for reading!');
+        $this->filename = $filename;
+        $this->stream = new BinaryStream($filename);
+        $this->stream->saveGroup('frame', array(
+            '_' => 1,
+            'mode' => 3,
+            '__' => 4,
+        ));
+        $this->scan();
+    }
+
+    protected function scan() {
+        if (!$this->stream->compare(5, '#!AMR'))
+            throw new Exception('File is not an amr file!');
+        $this->stream->readString(6);
+
+        $bitrates = array();
+
+        $frames = 0;
+        while (!$this->stream->isEnd()) {
+            $frames++;
+            $frame = $this->stream->readGroup('frame');
+            $bitrate = self::$modes[$frame['mode']];
+            if (isset($bitrates[$bitrate])) $bitrates[$bitrate]++;
+            else $bitrates[$bitrate] = 1;
+            $this->stream->readString(self::$frameSizes[$frame['mode']]);
+        }
+        $this->bitrates = $bitrates;
+        $this->length = 0.02 * $frames;
+    }
+
+    public function getLength() {
+        return $this->length;
+    }
+
+    public function getBitRate() {
+        return array_sum(array_keys($this->bitrates)) / count($this->bitrates);
+    }
+
+    public function getSampleRate() {
+        return 8000;
+    }
+
+    public function getChannelsMode() {
+        return self::MONO;
+    }
+
+    public function isVariableBitRate() {
+        return true;
+    }
+
+    public function isLossless() {
+        return false;
+    }
+}

src/MediaFile.php

@@ -12,6 +12,7 @@ class MediaFile {
     const FLAC = 'flac';
     const AAC = 'aac';
     const OGG = 'ogg';
+    const AMR = 'amr';
 
     protected $filename;
     protected $type;
@@ -46,6 +47,10 @@ static public function open($filename) {
                     $type = self::AUDIO;
                     $format = self::MP3;
                     break;
+                case 'amr':
+                    $type = self::AUDIO;
+                    $format = self::AMR;
+                    break;
                 default:
                     throw new Exception('Unknown file extension "'.$ext.'"!');
             }
@@ -78,6 +83,9 @@ public function __construct($filename, $type, $format) {
                 case self::MP3:
                     $this->adapter = new Mp3Adapter($filename);
                     break;
+                case self::AMR:
+                    $this->adapter = new AmrAdapter($filename);
+                    break;
 
                 default:
                     throw new Exception('Type "'.$type.'" does not have format "'.$format.'"!');