Add convenient Stream::getDimensions method to extract video dimension.

src/FFMpeg/Exception/LogicException.php

@@ -0,0 +1,16 @@
+<?php
+
+/*
+ * This file is part of PHP-FFmpeg.
+ *
+ * (c) Alchemy <info@alchemy.fr>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace FFMpeg\Exception;
+
+class LogicException extends \LogicException implements ExceptionInterface
+{
+}

src/FFMpeg/FFProbe/DataMapping/Stream.php

@@ -11,6 +11,10 @@
 
 namespace FFMpeg\FFProbe\DataMapping;
 
+use FFMpeg\Exception\LogicException;
+use FFMpeg\Exception\RuntimeException;
+use FFMpeg\Coordinate\Dimension;
+
 class Stream extends AbstractData
 {
     /**
@@ -32,4 +36,63 @@ class Stream extends AbstractData
     {
         return $this->has('codec_type') ? 'video' === $this->get('codec_type') : false;
     }
+
+    /**
+     * Returns the dimension of the video stream.
+     *
+     * @return Dimension
+     *
+     * @throws LogicException   In case the stream is not a video stream.
+     * @throws RuntimeException In case the dimensions can not be extracted.
+     */
+    public function getDimensions()
+    {
+        if (!$this->isVideo()) {
+            throw new LogicException('Dimensions can only be retrieved from video streams.');
+        }
+
+        $width = $height = $sampleRatio = $displayRatio = null;
+
+        if ($this->has('width')) {
+            $width = $this->get('width');
+        }
+        if ($this->has('height')) {
+            $height = $this->get('height');
+        }
+        if (null !== $ratio = $this->extractRatio($this, 'sample_aspect_ratio')) {
+            $sampleRatio = $ratio;
+        }
+        if (null !== $ratio = $this->extractRatio($this, 'display_aspect_ratio')) {
+            $displayRatio = $ratio;
+        }
+
+        if (null === $height || null === $width) {
+            throw new RuntimeException('Unable to extract dimensions.');
+        }
+
+        if (null !== $displayRatio && null !== $sampleRatio) {
+            $width = round($width / $sampleRatio[0] * $sampleRatio[1] * $displayRatio[0] / $displayRatio[1]);
+        }
+
+        return new Dimension($width, $height);
+    }
+
+    /**
+     * Extracts a ratio from a string in a \d+:\d+ format given a key name.
+     *
+     * @param  Stream     $stream The stream where to look for the ratio.
+     * @param  string     $name   the name of the key.
+     * @return null|array An array containing the width and the height, null if not found.
+     */
+    private function extractRatio(Stream $stream, $name)
+    {
+        if ($stream->has($name)) {
+            $ratio = $stream->get($name);
+            if (preg_match('/\d+:\d+/', $ratio)) {
+                return array_map(function ($int) { return (int) $int; }, explode(':', $ratio));
+            }
+        }
+
+        return null;
+    }
 }

src/FFMpeg/Filters/Video/ResizeFilter.php

@@ -12,6 +12,7 @@
 namespace FFMpeg\Filters\Video;
 
 use FFMpeg\Coordinate\Dimension;
+use FFMpeg\Exception\RuntimeException;
 use FFMpeg\Media\Video;
 use FFMpeg\Format\VideoInterface;
 
@@ -80,23 +81,21 @@ class ResizeFilter implements VideoFilterInterface
      */
     public function apply(Video $video, VideoInterface $format)
     {
-        $originalWidth = $originalHeight = null;
+        $dimensions = null;
+        $commands = array();
 
         foreach ($video->getStreams() as $stream) {
             if ($stream->isVideo()) {
-                if ($stream->has('width')) {
-                    $originalWidth = $stream->get('width');
-                }
-                if ($stream->has('height')) {
-                    $originalHeight = $stream->get('height');
+                try {
+                    $dimensions = $stream->getDimensions();
+                } catch (RuntimeException $e) {
+
                 }
             }
         }
 
-        $commands = array();
-
-        if ($originalHeight !== null && $originalWidth !== null) {
-            $dimensions = $this->getComputedDimensions(new Dimension($originalWidth, $originalHeight), $format->getModulus());
+        if (null !== $dimensions) {
+            $dimensions = $this->getComputedDimensions($dimensions, $format->getModulus());
 
             $commands[] = '-s';
             $commands[] = $dimensions->getWidth() . 'x' . $dimensions->getHeight();