When an interstitial has X-CUE="ONCE", the resume offset is ignored

[matvp91]

What version of Hls.js are you using?

v1.6.0-beta.2

What browser (including version) are you using?

132.0.6834.111

What OS (including version) are you using?

macOS 15

Test stream

N/A

Configuration

{}

Additional player setup steps

No response

Checklist

• The issue observed is not already reported by searching on Github under https://github.com/video-dev/hls.js/issues
• The issue occurs in the stable client (latest release) on https://hlsjs.video-dev.org/demo and not just on my page
• The issue occurs in the latest client (main branch) on https://hlsjs-dev.video-dev.org/demo and not just on my page
• The stream has correct Access-Control-Allow-Origin headers (CORS)
• There are no network errors such as 404s in the browser console when trying to play the stream

Steps to reproduce

As per spec:

If the X-RESUME-OFFSET is not present, the player uses the duration of interstitial playback for the resume offset, which is appropriate for live
playback where playback is to be kept at a constant delay from the live edge, or for VOD playback where the HLS interstitial is intended to replace content in the primary asset.

I've simulated a live stream with primary content and short, linear, ad pods in between. For each ad pod, there is an interstitial scheduled for "ad replacement" purposes.

...

#EXTINF:2.24
https://cdn.superstreamer.xyz/package/435028e4-0d63-47f1-8f8f-21eefaf14917/hls/video_1080_4000000_h264/9.m4s
#EXT-X-DATERANGE:ID="1738309865524",CLASS="com.apple.hls.interstitial",START-DATE="2025-01-31T08:51:05.524+01:00",X-RESTRICT="SKIP,JUMP",X-ASSET-LIST="http://localhost:52002/out/asset-list.json?dt=2025-01-31T08%3A51%3A05.524%2B01%3A00&sid=56498c0e-4be7-450b-9281-dab88803392e&mdur=20",X-CONTENT-MAY-VARY="YES",X-TIMELINE-OCCUPIES="POINT",X-TIMELINE-STYLE="HIGHLIGHT",X-PLAYOUT-LIMIT=20

The interstitial above correctly respects the X-PLAYOUT-LIMIT offset but once we add X-CUE="once", the playout limit is no longer respected. For reference, I'll add your comment from a PM here: "the schedule is being updated to remove the interstitial and this is interfering with resumption offset".

Expected behaviour

Respect the resumption offset unrelated to X-CUE.

What actually happened?

The resumption offset is ignored.

Console output

N/A

Chrome media internals output

N/A

[robwalch]

Hi @matvp91,

X-CUE="once"

Did you mean "ONCE"? "X-CUE" was promoted to a first class EXT-X-DATERANGE attribute: "CUE" with Trigger Identifiers PRE, POST, and ONCE (all caps).

When you are reproducing this issue, at what point is the client joining the live stream: before or mid interstitial?

If joining before, what is the latency before and after interstitial playback?

I created a live stream with an interstitial matching these attributes and could not reproduce the issue in dev. The stream began with 6 seconds of latency and resumed with the same amount. The interstitial played for only 20 seconds of it's 37 second duration.

Have you tried latest dev? This looks like it was resolved with the fix for #6911:

• Missing INTERSTITIALS_PRIMARY_RESUMED after Event with CUE ONCE #6911

[matvp91]

I rely on beta 2 from npm, which does not include the PR above. I have yet to try the latest dev branch but very likely we caught this with #6911.

I'll have an answer for you next week.

[robwalch]

This should be fixed in https://github.com/video-dev/hls.js/releases/tag/v1.6.0-beta.3