HLS ladder has a duplicated rung
Two variants are indistinguishable — same resolution, codec, dynamic range and bitrate — so one is wasted.
What it means
Two entries match on every attribute a player selects by. Note that several rungs at one resolution with *different* bitrates is deliberate and good practice; this is about true duplicates.
Why it matters
A duplicate rung gives the player no new option while adding a playlist entry and, usually, a whole encoding ladder’s worth of storage and origin cost. It is normally the result of a packaging job that ran twice or a merge that went wrong.
How to fix it
- Remove one of the two entries.
- If they are meant to differ — a backup origin, say — express that with PATHWAY-ID rather than a bare duplicate.
Check your own stream
The free HLS analyzer runs this check on every analysis and links each finding straight back here.
Open the HLS analyzer →Frequently asked questions
- What does "HLS ladder has a duplicated rung" mean?
- Two entries match on every attribute a player selects by. Note that several rungs at one resolution with *different* bitrates is deliberate and good practice; this is about true duplicates.
- Why does it matter?
- A duplicate rung gives the player no new option while adding a playlist entry and, usually, a whole encoding ladder’s worth of storage and origin cost. It is normally the result of a packaging job that ran twice or a merge that went wrong.
- How do I fix it?
- 1. Remove one of the two entries. 2. If they are meant to differ — a backup origin, say — express that with PATHWAY-ID rather than a bare duplicate.
- How can I detect this automatically?
- Paste your HLS streaming URL into StreamTest's free HLS analyzer. It runs this check on every analysis, flags the finding, and links straight back to this page — no sign-up required.
Related HLS checks
- HLS ladder has a bitrate inversionA lower-resolution variant is allocated more bandwidth than a higher-resolution one, so adaptive switching picks the wrong rendition.
- HLS variant is missing the CODECS attributeWithout CODECS, players must download a segment before they can tell whether they can play the rendition at all.
- HLS variant references an undeclared rendition groupA variant points at an AUDIO or SUBTITLES group that has no matching EXT-X-MEDIA entry, which breaks playback on strict players.
- HLS segment is longer than EXT-X-TARGETDURATIONA segment rounds to more than the declared target duration, which violates the HLS specification.
- HLS live window is shorter than three target durationsThe playlist holds too little content, so any player that falls slightly behind runs off the end of the window.
- HLS playlist has no EXT-X-PROGRAM-DATE-TIMEWithout program date-time the stream cannot be mapped to wall-clock time, which breaks DVR seeking and multi-stream alignment.