Choose the canvas before you export
Aspect ratio and resolution answer different questions
A 9:16 canvas is taller than it is wide; 16:9 is wider than it is tall. Neither ratio specifies the number of pixels. Use Resize / Canvas for the shape and layout. If your goal is a smaller file, another format, or a different output resolution, start with Transcode Video.
Fit preserves the picture; Fill prioritizes coverage
For a landscape recording on a portrait canvas, Fit keeps the full frame and leaves background above and below it. Fill covers the portrait canvas by cropping the sides. Check a frame with faces or captions near the edges before choosing; a full canvas does not mean the full original picture is visible.
What the illustrated result shows
The example below uses a six-second landscape clip, a 1:1 canvas, Fit, and the default black background. The result preview shows the landscape picture surrounded by background rather than stretched into a square. This is the illustrated output; it is not a before-and-after demonstration of every available layout.
Decide which change you actually need
If the video is sideways, rotating it may solve the problem without adding a new canvas. Resize changes the surrounding shape; rotation changes the picture’s orientation. Check the result again before saving to Photos.
01
Open Resize / Canvas in Process
Open Process, then tap Resize / Canvas.
02
Choose the video to process
In Select Video, tap Choose from Photos or Choose from Files and select your video. You can import a video even when the download list is empty.
03
Choose the canvas ratio
Select Canvas Ratio, then check Layout and background color. The example uses 1:1, Fit, and black.
Original, 16:9, 9:16, 1:1, 4:3, and 3:4
Original keeps the source ratio. 16:9 is a common landscape ratio, 9:16 portrait, and 1:1 square. A ratio describes width relative to height, rather than a pixel resolution such as 1080p.
Background Color*
#000000 is black. When Fit places a differently shaped picture inside the canvas, the remaining area shows this background. Changing the color requires VIP.
04
Choose Fit, Fill, or another layout
Open Layout, select a mode, then return to confirm the summary and tap Start Processing.
Fit keeps the whole picture
Fit scales the entire picture proportionally, potentially leaving background areas. Use it when subjects, subtitles, or edge details must remain visible.
Fill covers the canvas
Fill scales proportionally to cover the canvas and may crop edges when the ratios differ. Check subtitles, heads, and side edges in the preview.
Starred blur and multi-panel layouts
Blur 1:1*, Double 1:1*, Symmetric Double 1:1*, Triple 1:1*, and Triple Blur 1:1* are VIP blur-background or multi-panel layouts.
05
Check the result, then save or keep processing
Preview the output and check the canvas shape, edges, and background. With Fit, make sure the full picture remains visible before saving.
Preview and save
Play the result and check picture, duration, and sound, then tap Save to Photos. The first save may require permission to add photos and videos. After the success message, check the file in Photos.
What the other buttons do
Keep Processing takes the result into tool selection. Share File opens sharing options. Done closes the result page; it does not save to Photos.
Troubleshooting
Decide whether edge cropping is acceptable
Try Fit first when text or important subjects are near the edges. Try Fill for full coverage, and inspect important frames.
Frequently asked questions
Does changing the ratio stretch the picture?
Fit preserves proportions and adds background where needed. Preview other layouts before exporting to check for cropping or stretching.
How do I change pixel resolution?
This tool focuses on canvas ratio and layout. See the Resolution choices in Transcode Video for size and format conversion.
Try it on your device
ClipDock is free to download, with in-app purchases. Features and available options depend on the current app version.
Download on the App Store