✨ Support attachments

src/Attachment.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Danjones\FFMpeg;
+
+use FFMpeg\Format\FormatInterface;
+
+class Attachment extends Stream
+{
+    protected string $input = '';
+
+    public function __construct(Map $map, string $file = '')
+    {
+        $this->map = $map;
+        $this->input = $file;
+        // Shouldn't be necessary, but just in case
+        $this->codec = new Format\Copy();
+    }
+
+    public function mime(string $mime): static
+    {
+        return $this->addMetadata('mimetype', $mime);
+    }
+
+    public function setCodec(FormatInterface $codec): static
+    {
+        return $this;
+    }
+
+    protected function parseCodec(): static
+    {
+        return $this;
+    }
+
+    public function saveAttachment(): Map
+    {
+        return $this->saveStream();;
+    }
+
+    public function buildCommand(int $idx = 0): array
+    {
+        $commands    = parent::buildCommand($idx);
+        $commands[0] = '-attach';
+
+        return $commands;
+    }
+}