Adaptive bitrate streaming (ABR) is a delivery method in which a video is encoded at several bitrates and resolutions, split into short segments, and the player picks the best version for each segment based on current network speed and device capability.
Why it matters
Viewers have different devices and connections, and a single connection fluctuates. ABR keeps playback going by trading quality for continuity, so a drop in bandwidth shows as a softer picture for a few seconds rather than buffering. Common implementations are HLS and MPEG-DASH, and segments are normally delivered over HTTP through a CDN.
Example
A streaming ladder might look like this:
- 1080p at 5 Mbps
- 720p at 3 Mbps
- 480p at 1.2 Mbps
- 240p at 0.4 Mbps
The player downloads a manifest listing these versions. If measured throughput falls from 8 Mbps to 2 Mbps, it switches from 1080p to 480p at the next segment boundary and switches back when speed recovers.
Common mistakes
- Offering a ladder with large gaps between rungs, which causes abrupt quality jumps.
- Using very long segments, which slows the player's reaction to changing conditions.
- Forgetting that more renditions mean more storage and encoding cost.
Related
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