How Adaptive Video Quality Works on a Shared Clip

Save Replay creates HLS renditions at suitable heights for the processed source rather than enlarging every clip to the same ladder. A 1080p source currently produces 360p, 720p, and 1080p renditions. A 540p source produces 360p and 540p. Sources above 1080p can add a source-sized rendition up to the current 1440p processing limit.

Each rendition is encoded as H.264 video with AAC audio and split into roughly four-second HLS segments. A master playlist records the bitrate and resolution of each rendition. The watch page receives those rendition details only after HLS processing has completed successfully.

When hls.js is supported, Auto can seed its estimate from the browser's reported downlink. If the browser exposes no recent estimate, the player starts with a bandwidth probe. Data Saver removes the configured 720p quality floor, and hls.js replaces its starting estimate with throughput measured while it downloads segments.

Some browsers play HLS through their native media support instead. In that path, the browser manages automatic switching. The Save Replay quality menu appears only while the page is using an adaptive stream and has rendition choices to show, so viewers on a direct MP4 fallback will not see the same controls.

A manual level can help when Auto is slow to react, a connection is unstable, or small text needs more detail. Selecting 360p reduces the requested video bitrate; selecting 1080p asks for more pixels and a higher bitrate when that rendition exists. The source resolution still limits the menu.

Choosing a level cannot repair a weak connection or add detail absent from the source. Return to Auto when conditions may change. If the adaptive stream or its player cannot load, Save Replay tries the ready processed MP4 when one is available rather than claiming that every browser can play every HLS rendition.