Delivery mechanism
Adaptive Bitrate Streaming
Adaptive bitrate streaming means the player chooses between several versions of the same video while it plays, moving up or down as conditions change. The part most explanations leave out is the constraint: a player can only choose from the renditions that were actually produced for that video. So this page explains the mechanism, and then the five conditions — source, project configuration, processing time, plan and client — that decide what there is to choose from and what a viewer ends up seeing.
A per-project rendition ladder
illustration — enabled heights are a project setting, bounded by the source
- Poor
- Mobile
- Wifi
- Fibre
The mechanism
What adaptive bitrate streaming is
One video, several encoded versions, and a player deciding between them segment by segment.
Rather than sending one fixed file, adaptive delivery offers the same video at several quality levels. The video is cut into short segments, and a manifest lists the levels available. The player reads that manifest and requests the next segment at the level it estimates the connection can sustain, revising as it goes — so a connection that tightens mid-playback can drop a level instead of stalling, and one that improves can climb again.
HLS is the protocol used for that here when a project is configured to produce HLS output. Support in a given browser, operating system or television is a property of the viewer's client rather than of this platform, so it is worth verifying against the device mix your audience actually uses instead of assuming it universally.
The important consequence is simple, and it is the thing to take from this page: adaptation can only work with what exists. If a video has just one high rendition, there is nothing to fall back to when the connection tightens — which is the most common cause of stalling that gets attributed to delivery.
The conditions
What bounds the ladder and the playback result
Five conditions, each of which can be checked rather than assumed.
The source
Processing cannot create detail a source never had. The resolution and bitrate you upload set the ceiling on the renditions that can meaningfully be produced from it.
The project's rendition set
Which heights are produced is a per-project choice from an enumerated list, each with its own bitrate setting. There is no single fixed ladder applied to every video, and whether a low fallback rendition exists is a decision someone made on that project.
The output format
HLS output is a project setting and can be off; a project may be configured for CMAF instead, which certified DRM requires. Adaptive HLS selection applies to the projects that actually produce HLS output — not to all delivery everywhere.
When it was processed
Project settings apply to material processed after they are set. Changing the rendition set today does not re-process a library uploaded last year, so an older video keeps whatever it was given at the time.
Your plan
Capabilities are recorded against each plan, and some are entitlements checked when you switch them on. Confirm what your plan carries on the pricing page rather than assuming a feature is universal.
The client
The final decision is made by the player on a device we do not control, on a connection we cannot see. That is why no page here promises buffer-free playback on any device or any connection.
Compared with
Adaptive streaming and progressive download
Worth understanding as a trade-off rather than as an upgrade with no cost.
A progressive download sends one file at one quality. If it suits the viewer's connection, it is perfectly adequate; if it does not, there is no mechanism to adjust, so the viewer waits. It also means everyone receives the same bitrate regardless of whether their screen or connection can use it.
Adaptive delivery trades that simplicity for choice: more work at processing time, more storage for the additional renditions, and a manifest for the player to negotiate against. In return, a struggling connection can be met with a lower level rather than a stall. Whether that trade is worth it depends on your audience — and if your viewers are all on one predictable network, it may matter less than the internet generally assumes.
Practical
Checking adaptive delivery on your own video
Four checks that tell you what a viewer's player actually has to work with.
- 01
Confirm the project's output format
- 02
Look at which renditions exist
- 03
Check when the video was processed
- 04
Watch it under constraint
Common questions
Adaptive streaming questions
Answered against the project contract rather than the marketing version.
Is adaptive streaming applied to every video?
No, and an earlier version of this page said it was. Whether HLS output is produced is a per-project setting that can be off, and a project may be configured for another format instead — certified DRM, for example, requires CMAF. Which renditions are produced is likewise a per-project choice from an enumerated list of heights, so there is no fixed ladder applied everywhere. Check the project the video belongs to rather than assuming.
Which resolutions will my videos have?
Whichever heights are enabled on that project, bounded by what the source can support and by what your plan records. The old copy listed a fixed set from 360p to 4K as though it applied to every upload; that was wrong. If a low fallback rendition matters to you — and for viewers on poor connections it usually matters most — confirm it is enabled before you rely on it.
Does adaptive streaming mean nobody buffers?
No. Adaptation reduces the chance of a stall by letting the player choose a level it can sustain, but it can only choose from what exists, and the viewer's device and connection are outside our control. Any page promising zero buffering on any device and any connection is promising something it cannot see — including, until this correction, this one.
If I change the settings, do my existing videos update?
Not on their own. Project settings apply to material processed after they are set, so an existing library keeps the outputs it was given at the time. If older videos need a different rendition set, that is a re-processing conversation rather than a toggle — talk to us with the specific project in mind.
Is adaptive streaming included in my plan?
Capabilities are recorded against each plan rather than granted universally, and this page makes no every-plan claim. Read the plan card for the band you are considering on the pricing page, which is generated from the live catalogue, and if a specific delivery capability decides your purchase, ask us to confirm it in writing.
Put this on your own pages, under your own rules
Check what your project actually produces, watch it under a constrained connection, and decide from that rather than from a specification.