ABR
ABR (Adaptive Bitrate) streaming allows the player to automatically switch between different quality levels based on the viewer's available bandwidth and device capabilities. When bandwidth drops, the player steps down to a lower quality to avoid buffering; when bandwidth improves, it steps back up for a better picture.
The set of available quality levels is defined by an ABR ladder. Each rung on the ladder specifies a resolution, bitrate, and frame rate. The media engine transcodes the incoming stream into all configured rungs simultaneously, so the player can pick the best one in real time.
Here is an example of a typical ABR ladder:
| Resolution | Bitrate | Frame rate |
|---|---|---|
| 1920×1080 | 4 500 kbps | 30 fps |
| 1280×720 | 2 500 kbps | 30 fps |
| 640×360 | 1 000 kbps | 30 fps |
Since the ladder has impact on pricing and is difficult to get right, setting up available ABR ladders is done during onboarding. If later on new ladders are needed, don't hesitate to contact us.
Important considerations
- Frame rate — the frame rate of the encoder and the channel configuration should match (suggested values: 25, 29.97, 30, 50, 59.94 or 60 fps). Mismatches may lead to information loss and stalls.
- Ingest bitrate — the encoder bitrate should be at least as high as the highest rung of the ABR ladder so the transcoder receives a high-quality source for all output qualities.