FA-27668 / HTTP ranges / Member archive

A media player maps a seek time to keyframe-aligned byte range requests around cached spans: a one-byte uncached window tail is still requested · case 03

A media player maps a seek time to keyframe-aligned byte range requests around cached spans: a one-byte uncached window tail is still requested.

Member previewVariant 3 · 3 implementations · 18 checks per implementation

Case contract

x has a time-sorted keyframe index [time,byte-offset], total length, init header length H (bytes 0..H-1), seek time, byte window and cached inclusive spans (unordered). Request the header unless one cached span covers all of it. Start at the last keyframe with time<=seek, or the first keyframe when seeking earlier. A start offset at or beyond total, an empty index or nonpositive total returns null. The media window is [start,min(total-1,start+window-1)]; request only its uncached gaps in ascending order, as inclusive bytes=a-b values after any header request.

Why this case matters

Range responses combine representation identity, conditional requests, framing, and partial-object state.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
tail-emit fixture 12	`[]`	`["bytes=799-799"]`	Failed

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