Add MP3 audio extraction

src/AudioStream.php

@@ -0,0 +1,100 @@
+<?php
+
+namespace swf2ass;
+
+class AudioStream{
+    const FORMAT_UNCOMPRESSED_NATIVE_ENDIAN = 0;
+    const FORMAT_UNCOMPRESSED_LITTLE_ENDIAN = 3;
+
+    const FORMAT_ADPCM = 1;
+
+    const FORMAT_MP3 = 2;
+
+    const FORMAT_NELLYMOSER_16 = 4;
+    const FORMAT_NELLYMOSER_8 = 5;
+    const FORMAT_NELLYMOSER = 6;
+
+    const FORMAT_SPEEX = 11;
+
+
+    private int $format;
+    private int $sampleRate;
+    private int $sampleSize;
+    private int $channels;
+
+    private ?int $start = null;
+
+
+    private array $frames = [];
+
+    public function __construct(int $format, int $sampleRate, int $sampleSize, int $channels){
+        $this->format = $format;
+        $this->sampleRate = $sampleRate;
+        $this->sampleSize = $sampleSize;
+        $this->channels = $channels;
+    }
+
+    public function getFormat() : int{
+        return $this->format;
+    }
+
+    public function setStartFrame(?int $start){
+        $this->start = $start;
+    }
+
+    public function getStartFrame() : ?int{
+        return $this->start;
+    }
+
+    public function addStreamBlock(array $node){
+        if($node["tagType"] !== "SoundStreamBlock"){
+            throw new \Exception("Invalid tag ". $node["tagType"] );
+        }
+
+        switch ($this->format){
+            case self::FORMAT_MP3:
+                $this->addMP3SoundData($node["soundStreamData"]);
+                break;
+        }
+    }
+
+    private function addMP3SoundData(string $bin){
+        $offset = 0;
+        [,$sampleCount] = unpack("v", $bin, $offset);
+        $offset += 2;
+        [,$seekSamples] = unpack("s", $bin, $offset);
+        $offset += 2;
+
+        $frameSize = $this->sampleRate <= 11025 ? 576 : 1152;
+        $this->frames[] = substr($bin, $offset);
+    }
+
+    public function getAudioData() : string{
+        //TODO: header?
+        return implode("", $this->frames);
+    }
+
+    public static function fromSoundStreamHeadTag(array $node) : ?AudioStream{
+        if(!isset($node["streamSoundCompression"]) or !isset($node["streamSoundRate"]) or !isset($node["streamSoundSize"]) or !isset($node["streamSoundType"])){
+            return null;
+        }
+
+        $rate = null;
+        switch ($node["streamSoundRate"]){
+            case 0:
+                $rate = 5512;
+                break;
+            case 1:
+                $rate = 11025;
+                break;
+            case 2:
+                $rate = 22050;
+                break;
+            case 3:
+                $rate = 44100;
+                break;
+        }
+
+        return new AudioStream($node["streamSoundCompression"], $rate, $node["streamSoundSize"] === 1 ? 16 : 8, $node["streamSoundType"] === 1 ? 2 : 1);
+    }
+}

src/SWFProcessor.php

@@ -14,7 +14,7 @@ class SWFProcessor extends SWFTreeProcessor {
 
     private float $frameRate;
 
-    private $audio = null;
+    private ?AudioStream $audio = null;
 
     private Rectangle $viewPort;
 
@@ -51,7 +51,7 @@ class SWFProcessor extends SWFTreeProcessor {
         return $this->viewPort;
     }
 
-    public function getAudio() {
+    public function getAudio() : ?AudioStream {
         return $this->audio;
     }
 
@@ -68,18 +68,17 @@ class SWFProcessor extends SWFTreeProcessor {
                 return $node["tagType"];
             case "SoundStreamHead":
             case "SoundStreamHead2":
-                $this->audio = (object)["node" => $node, "start" => null, "content" => [],];
+                $this->audio = AudioStream::fromSoundStreamHeadTag($node);
                 return $node["tagType"];
             case "DefineSound":
-                $this->audio = (object)["node" => $node, "start" => $this->getFrame(), "content" => []];
+                //TODO $this->audio = (object)["node" => $node, "start" => $this->getFrame(), "content" => []];
                 return $node["tagType"];
             case "SoundStreamBlock":
-                if ($this->audio !== null) {
-                    if ($this->audio->start === null) {
-                        $this->audio->start = $this->getFrame();
+                if($this->audio !== null){
+                    if($this->audio->getStartFrame() === null){
+                        $this->audio->setStartFrame($this->getFrame());
                     }
-                    //$audio .= substr($data, 2);
-                    $this->audio->content[] = [$this->getFrame(), $node["soundStreamData"]];
+                    $this->audio->addStreamBlock($node);
                 }
                 return $node["tagType"];
         }

swf2ass.php

@@ -127,10 +127,10 @@ if ($swf->header["signature"]) {
     while(($frame = $processor->nextFrameOutput()) !== null){
         $audio = $processor->getAudio();
         if($audio !== null and $frameOffset === 0){
-            if($audio->start === null){
+            if($audio->getStartFrame() === null){
                 continue;
             }
-            $frameOffset = $audio->start;
+            $frameOffset = $audio->getStartFrame();
         }
         $lastFrame = $frame;
 
@@ -222,6 +222,12 @@ if ($swf->header["signature"]) {
     foreach ($assRenderer->flush($lastFrame) as $line){
         fwrite($fp, $line . "\n");
     }
+
+    if($processor->getAudio() !== null and $processor->getAudio()->getFormat() === \swf2ass\AudioStream::FORMAT_MP3){
+        $audioFp = fopen($argv[2] . ".mp3", "w+");
+        fwrite($audioFp, $processor->getAudio()->getAudioData());
+        fclose($audioFp);
+    }
 }
 
 if(count($testVectors) > 0){