Changing the aspect ratio of a video is useful for adapting videos to different screen sizes and dimensions. The aspect ratio defines the proportional relationship between the width and height of an image or video frame. Some common aspect ratios are 4:3, 16:9, 21:9, etc. Modifying the aspect ratio can help avoid black bars, pillarboxing, and distorted images when displaying a video on screens with a different aspect ratio than the original.
What is aspect ratio?
The aspect ratio of an image or video refers to the proportional relationship between its width and height. It is expressed as a ratio of width to height, written as W:H. For example:
- 4:3 – Standard definition TVs and computer monitors
- 16:9 – High definition and Full HD displays
- 21:9 – Ultrawide computer monitors and TVs
Some common aspect ratios are:
Aspect Ratio | Dimensions |
---|---|
4:3 | Almost square (wider than it is tall) |
16:9 | Rectangular widescreen |
21:9 | Super widescreen |
The aspect ratio is an important consideration when viewing videos on different devices. A mismatch between the aspect ratios of the video and display will result in black bars, cropping, and image distortion. Changing the video’s aspect ratio can help avoid these issues.
Why change the video aspect ratio?
There are several reasons you may want to modify the aspect ratio of a video:
Avoid black bars and pillarboxing
Black bars appear on the top/bottom or sides of the video when its aspect ratio does not match the display. This is called letterboxing on top/bottom and pillarboxing on the sides. Changing the aspect ratio to match the screen avoids wasted screen space and small picture size.
Prevent image distortion
Displaying a widescreen video on a standard 4:3 display can stretch and warp the image. Similarly, a 4:3 video on a widescreen may get squeezed horizontally. Changing the aspect ratio preserves the proper image geometry and proportions.
Fit multiple videos to the same size
Setting all videos to a common aspect ratio like 16:9 allows displaying uniform sized videos side by side without distortion. Useful for video walls and presentation screens.
Optimize for social media
Social platforms like Instagram and TikTok work best with square 1:1 and vertical 9:16 videos. Converting landscape videos to these sizes optimizes them for mobile viewing.
Creative preference
Cinematographers may choose non-standard aspect ratios for creative reasons. Movies shot in wide 21:9 or narrow 4:3 help evoke different visual styles.
How to change video aspect ratio
There are several ways to change the aspect ratio of videos:
Video editing software
All video editing programs like Premiere Pro, Final Cut Pro, Vegas Pro etc. provide aspect ratio controls. This method offers the most flexibility and fine-tuned control over the final outcome.
Steps:
- Import the video into video editor timeline.
- Select the video and open video effects settings.
- Find the sizing/geometry/transform options and select the desired new aspect ratio.
- Render or export the video in desired format.
Media converters
Online media converters like Cloudconvert, Zamzar, Online-Convert etc. provide quick aspect ratio changes through their web interfaces. Simply upload a video, choose the new dimensions, and download the converted file.
FFmpeg command line
For batch processing, FFmpeg is a popular open-source command line tool for audio/video transformations. The -aspect parameter changes aspect ratios.
Example syntax:
ffmpeg -i input.mp4 -aspect 16:9 output.mp4
VLC Media Player
The popular VLC media player has a handy aspect ratio conversion feature.
Steps:
- Open the video file in VLC.
- Right click on the video frame and select ‘Aspect Ratio’.
- Choose the desired new aspect ratio.
- Go to Tools > Preferences and set ‘Video->Aspect Ratio’ to Custom.
- Save the changes to keep the selected aspect ratio.
Best practices for aspect ratio conversion
Follow these tips for optimal results when changing aspect ratios:
- Maintain the original aspect if possible – Avoid distortion from drastic aspect changes like 4:3 to 16:9.
- Choose proper pillarboxing/letterboxing colors if required – match video background or use black.
- For YouTube uploads, 16:9 is recommended.
- Test on target devices before finalizing.
- Balance element positioning – Don’t cut out key details from frame edges.
- Use highest quality source footage possible.
Conclusion
Modifying aspect ratios allow displaying videos uniformly across varied screens and devices. Powerful video editing software provides fine-tuned control over the transformation process. Online media converters offer quick and easy aspect ratio changes. The optimal target aspect ratio depends on the intended viewing devices and preservation of original image composition. With the proper tools and techniques, changing video aspect ratios can be straightforward.