Quality Presets & Resolutions
When you upload a video you choose a videoQuality preset. AntCDN encodes your video into a ladder of renditions from that preset, and players switch between them as the viewer’s connection changes.
The presets
Resolutions are short-edge lengths. Bitrates are targets for H.264 video; audio is encoded once and shared by every rendition.
| Rendition | standard | high | ultra |
|---|---|---|---|
| 240p | 0.12 Mbps · 30 fps | 0.12 Mbps · 30 fps | 0.12 Mbps · 30 fps |
| 480p | 0.8 Mbps · 30 fps | 0.8 Mbps · 30 fps | 0.8 Mbps · 30 fps |
| 720p | 1.2 Mbps · 30 fps | 1.2 Mbps · 30 fps | 1.2 Mbps · 120 fps |
| 1080p | 2.5 Mbps · 30 fps | 3.5 Mbps · 60 fps | 5 Mbps · 120 fps |
| 1440p | — | 4.5 Mbps · 60 fps | 6 Mbps · 120 fps |
| 2160p (4K) | — | 8 Mbps · 60 fps | 12 Mbps · 120 fps |
Frame rates are ceilings: a rendition never exceeds your source’s frame rate, so a 24 fps film stays at 24 fps in every rendition.
AntCDN never upscales
Renditions larger than your source are skipped, and no rendition’s bitrate exceeds your source’s bitrate. A 1080p upload with ultra gets renditions up to 1080p only — choosing a higher preset never inflates a lower-resolution source.
Short edge: landscape, vertical, and square video
Every resolution on this page, and in the playback quality controls, refers to the video’s short edge:
| Source orientation | Short edge | Example source | Its 2160p rendition |
|---|---|---|---|
| Landscape | height | 3840 × 2160 | 3840 × 2160 |
| Vertical (portrait) | width | 2160 × 3840 | 2160 × 3840 |
| Square | width (= height) | 2160 × 2160 | 2160 × 2160 |
The other edge follows your source’s aspect ratio. So a vertical phone video keeps its full resolution: a 1080 × 1920 upload gets a 1080 × 1920 top rendition, labelled 1080p.
Note
Widescreen films are measured the same way. A 3840 × 1600 (2.40:1) master has a short edge of 1600, which sits between the 1440p and 2160p rungs, so its top rendition is 1440p (3456 × 1440).
Checking what was encoded
The video details endpoint returns the ladder that was produced for a video. Each entry in encodings has a shortEdgePixels value and a shortEdgeIsWidth flag (true for vertical and square sources).
curl "https://api.antcdn.net/v1/videos/{assetId}" \ -H "X-Api-Key: YOUR_API_KEY"