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What is Video Aspect Ratio?

Video aspect ratio expresses the proportional relationship between a frame’s displayed width and height, such as 16:9 or 9:16. It can differ from raw pixel dimensions when the pixels are not square.

How Video Aspect Ratio works

Displayed aspect ratio is derived from the stored raster, any pixel-aspect declaration, clean aperture or crop, and orientation metadata. Consequently, two streams with identical pixel dimensions can be intended for different display shapes, while anamorphic material can display correctly without square pixels. Players resolve these signals before fitting the picture into a viewport. Aspect handling appears during ingest normalization, cropping, rendition creation, thumbnails, and responsive layout.

Key facts

  1. For uncropped material, display width-to-height equals the stored raster ratio multiplied by the pixel aspect ratio; assuming square pixels can visibly stretch anamorphic sources.
  2. Rotation metadata can swap the effective display orientation without rearranging stored samples, so a portrait recording may be encoded in a landscape-shaped raster.
  3. A contain fit preserves the full frame with unused space, while a cover fit fills the viewport by cropping; neither choice corrects wrongly signaled source aspect metadata.

When Video Aspect Ratio matters

Match player layout and output crops to the intended display ratio. Ignoring source and pixel aspect ratios can produce stretching, unwanted cropping, pillarboxing, or letterboxing.

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