Add audio formats MP3 and Flac

src/FFMpeg/Format/Audio/Flac.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace FFMpeg\Format\Audio;
+
+use FFMpeg\Format\DefaultAudioFormat;
+
+class Flac extends DefaultAudioFormat
+{
+
+    protected $audioCodec = 'flac';
+
+    protected function getAvailableAudioCodecs()
+    {
+        return array('flac');
+    }
+
+}

src/FFMpeg/Format/Audio/Mp3.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace FFMpeg\Format\Audio;
+
+use FFMpeg\Format\DefaultAudioFormat;
+
+class Mp3 extends DefaultAudioFormat
+{
+
+    protected $audioCodec = 'libmp3lame';
+
+    protected function getAvailableAudioCodecs()
+    {
+        return array('libmp3lame');
+    }
+
+}

src/FFMpeg/Format/DefaultAudioFormat.php

@@ -7,7 +7,7 @@ abstract class DefaultAudioFormat implements AudioFormat
 
     protected $audioCodec;
     protected $audioSampleRate = 44100;
-    protected $kiloBitrate     = 1000;
+    protected $kiloBitrate     = 128;
 
     public function getExtraParams()
     {

src/FFMpeg/Format/DefaultVideoFormat.php

@@ -7,9 +7,10 @@ abstract class DefaultVideoFormat extends DefaultAudioFormat implements VideoFor
 
     protected $width;
     protected $height;
-    protected $frameRate = 25;
+    protected $frameRate   = 25;
     protected $videoCodec;
-    protected $GOPsize   = 25;
+    protected $GOPsize     = 25;
+    protected $kiloBitrate = 1000;
 
     public function __construct($width, $height)
     {

src/FFMpeg/Format/VideoFormat.php

@@ -2,7 +2,7 @@
 
 namespace FFMpeg\Format;
 
-interface VideoFormat
+interface VideoFormat extends AudioFormat
 {
 
     public function getWidth();