Read a complete HLS media playlist as a duration ledger

The useful distinctions

• EXTINF gives the following segment's duration.
• EXT-X-PLAYLIST-TYPE:VOD identifies a playlist that does not change.
• EXT-X-ENDLIST indicates that no further segments will be added.

Turn the list into intervals

The invented presentation contains two segments lasting 6.0 and 5.5 seconds. A useful worksheet places the first at presentation interval zero through six and the second at six through eleven and a half. Adding the values gives the described presentation length. That sum answers a different question from the target-duration field, which is a playlist-level bound rather than a promise that every segment lasts exactly that long.

Keep text validity separate from media validity

The sample is a complete media-playlist text example, but no media objects accompany it. Its duration declarations have therefore been reviewed as arithmetic, not measured against encoded samples. A real publication check would compare the declarations with the referenced media, verify that the relative references resolve, and confirm the objects are retained. The final marker concerns whether this list will grow; it does not prove that every object is downloadable. Likewise, choosing VOD is a mutability commitment, not an instruction to append new recordings to the same published playlist. If the presentation changes, review the publication version and caching policy as separate engineering decisions. If a later edit changes the second declaration to 4.5 seconds, update the duration ledger to 10.5 seconds. That is a change in the playlist's described timeline, not a measured duration of media bytes.

Worked example · synthetic

The declared duration is 6.0 + 5.5 = 11.5 seconds. The relative references are synthetic and have not been fetched; target duration six is consistent with these declarations.

Synthetic text example; no network operation has been performed.

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-PLAYLIST-TYPE:VOD
#EXT-X-TARGETDURATION:6
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:6.0,
segment-a.ts
#EXTINF:5.5,
segment-b.ts
#EXT-X-ENDLIST

Check the interpretation

• Sum the EXTINF values.
• Check each declaration against target-duration requirements.
• Validate actual sample durations separately when media exists.