feat: Split Youtube downloads in smaller chunks

Fixes #217

classes/YoutubeStream.php

@@ -0,0 +1,38 @@
+<?php
+/**
+ * YoutubeStream class.
+ */
+
+namespace Alltube;
+
+use GuzzleHttp\Psr7\AppendStream;
+
+/**
+ * Stream that downloads a video in chunks.
+ * This is required because Youtube throttles the download speed on chunks larger than 10M.
+ */
+class YoutubeStream extends AppendStream
+{
+    /**
+     * YoutubeStream constructor.
+     *
+     * @param Video $video Video to stream
+     */
+    public function __construct(Video $video)
+    {
+        parent::__construct();
+
+        $stream = $video->getHttpResponse();
+        $fileSize = $stream->getHeader('Content-Length');
+        $curSize = 0;
+        while ($curSize < $fileSize[0]) {
+            $newSize = $curSize + $video->downloader_options->http_chunk_size;
+            if ($newSize > $fileSize[0]) {
+                $newSize = $fileSize[0] - 1;
+            }
+            $response = $video->getHttpResponse(['Range' => 'bytes='.$curSize.'-'.$newSize]);
+            $this->addStream(new YoutubeChunkStream($response));
+            $curSize = $newSize + 1;
+        }
+    }
+}