ResizeFilter with ffmpeg autorotation

[giulioprovasi]

Q	A
Bug?	yes
New Feature?	no
Version Used	Specific tag or commit sha
FFmpeg Version	FFmpeg 5.1.2
OS	arch linux

Actual Behavior

When doing a vertical video conversion, the resize filter stretches the video

Expected Behavior

Applying the resize filter should keep into consideration the input video rotation

Steps to Reproduce

require 'vendor/autoload.php';

$ffmpeg = FFMpeg\FFMpeg::create();
$video = $ffmpeg->open('video.mov');
$video->filters()
    ->resize(
        new FFMpeg\Coordinate\Dimension(320, 180),
        FFMpeg\Filters\Video\ResizeFilter::RESIZEMODE_INSET
    )
    ->synchronize();

$video
    ->frame(FFMpeg\Coordinate\TimeCode::fromSeconds(10))
    ->save('frame.jpg'); // stretched
$video
    ->save(new FFMpeg\Format\Video\X264(), 'export-x264.mp4'); // stretched

example taken from here

Possible Solutions

I actually tried this and works for my use case, maybe we may change the ResizeFilter accordingly ? (I may work on a PR if this works for you)

- $commands[] = '[in]scale=' . $dimensions->getWidth() . ':' . $dimensions->getHeight() . ' [out]';
+ $commands[] = "[in]scale=w='if(gt(iw\,ih),{$dimensions->getWidth()},{$dimensions->getHeight()})':h='if(gt(iw\,ih),{$dimensions->getHeight()},{$dimensions->getWidth()})'[out]";

By checking the input width/height before applying the resize filter, the output video has a good format/orientation.

Maybe the ResizeFilter may introduce a default parameter to "handle auto detect of input orientation"

-    public function __construct(Dimension $dimension, $mode = self::RESIZEMODE_FIT, $forceStandards = true, $priority = 0)
+    public function __construct(Dimension $dimension, $mode = self::RESIZEMODE_FIT, $forceStandards = true, $priority = 0, $guessOrientation = false)

...

+ if ($this->guessOrientation) {
+    $commands[] = "[in]scale=w='if(gt(iw\,ih),{$dimensions->getWidth()},{$dimensions->getHeight()})':h='if(gt(iw\,ih),{$dimensions->getHeight()},{$dimensions->getWidth()})'[out]";
+ } else {
   $commands[] = '[in]scale=' . $dimensions->getWidth() . ':' . $dimensions->getHeight() . ' [out]';
+ }

[fritzmg]

I noticed the same issue. Had a 1080x1920 vertical video from an iPhone (according to the meta data it has a 90° rotation) and when using

$video
    ->filters()
    ->resize(new Dimension(1920, 1080), ResizeFilter::RESIZEMODE_INSET, false)
    ->synchronize()
;

the video will end up being a 1920x1080 stretched video, instead of 607x1080 (which I would have expected at least).

[fritzmg]

Using this solution solves the issue for me: #177 (comment)