How to Stack Two Videos with Different Resolutions Horizontally Using FFmpeg

Stacking two videos with different resolutions can be a challenging task, especially when you want to keep their original audio and display them side by side in a single video. In this article, we will explore how to use FFmpeg's powerful filters to achieve this task.

The first step is to identify the resolution of each video. For our example, let's assume that one video has a resolution of 1280x720 pixels (HD), while the other has a resolution of 640x480 pixels (VGA). To stack these videos horizontally using FFmpeg, we will use the `scale2ref` filter.

The `scale2ref` method scales or resizes the input video based on a reference video. This is useful when you want to match the resolution of one video with another. In our case, we will use this filter to scale the second video (640x480) to match the resolution of the first video (1280x720).

The command to do the trick will be:

```

ffmpeg -i main-video.mp4 -i right-side-video.mp4 -filter_complex 'scale2ref='oh*mdar':'if(lt(main_h,ih),ih,main_h)' 'out'' -map 'out' -ac 2 output.mp4

```

Let's break down this command:

* `-i main-video.mp4` and `-i right-side-video.mp4` specify the input files.

* `filter_complex 'scale2ref='oh*mdar':'if(lt(main_h,ih),ih,main_h)' 'out''` applies the `scale2ref` filter to the second video, scaling it based on the main video's resolution. The `'out'` label specifies the output of this filter.

* `-map 'out'` maps the filtered output to the final video stream.

* `-ac 2` specifies that we want to keep the audio from both videos.

By using the `scale2ref` filter, we can easily match the resolution of our two input videos. This is especially useful when you're dealing with web camera streams or other scenarios where the resolution may vary.

In conclusion, stacking two videos with different resolutions horizontally using FFmpeg's `scale2ref` filter is a powerful and efficient way to create a single video from multiple sources while maintaining their original audio. By following this guide, you should be able to achieve this task with ease.

Ffmpeg scale to 1080p