HLS Lens

Read HLS manifests in VS Code — with the manifest telling you what is wrong with it.

An .m3u8 file is a list of claims, and a text editor shows you all of them equally. HLS Lens reads a manifest the way someone who has debugged a stream reads it, and reports what it finds on the line you have to fix.

• Usage — commands, the tree, the deep check, settings
• Rule reference — all 84 rules with the reason each one matters
• Roadmap — what is shipped and what is next, generated from the backlog
• Source on GitHub

This site is built from the same markdown the repository keeps, by a renderer that is part of the extension: no theme, no framework, no dependency — the same rule the code follows.

In one screenshot's worth of words

#EXTM3U
#EXT-X-VERSION:3                        ← error   syntax/version-too-low
#EXT-X-TARGETDURATION:6                          EXT-X-MAP needs 6
#EXT-X-PLAYLIST-TYPE:VOD                ← error  media/missing-endlist
#EXT-X-KEY:METHOD=AES-128,URI="http://…" ← error  media/key-over-http
#EXT-X-MAP:URI="init.mp4"
#EXTINF:8.500,                          ← error   media/extinf-exceeds-target
seg-01205.m4s                                    8.5s against a 6s target

Two layers, on purpose

The 84 rules in the extension read the manifest: they are instant, work offline, and need nothing installed. The defects that cannot be seen from the manifest — a timeline gap no EXT-X-DISCONTINUITY declares, a 1080p rung whose bitstream codes 720p, a real segment duration that drifts from its EXTINF — need the segment bytes, and those are segcheck's job. HLS Lens: Deep Check Segments runs it and brings its findings into the same Problems panel.

Nothing in the extension reimplements a demuxer, and nothing in segcheck duplicates a manifest rule.