LL-HLS PART-HOLD-BACK is below three part durations
The declared PART-HOLD-BACK is smaller than three times PART-TARGET, so players chase a live edge they cannot reach.
What it means
In low-latency HLS, PART-HOLD-BACK tells the player how far behind the live edge to start. The specification requires it to be at least three times PART-TARGET.
Why it matters
Set too low, the player starts closer to the edge than the server can reliably serve. Every jitter in part production becomes a stall, so the stream rebuffers continuously on exactly the connections low latency was supposed to help.
How to fix it
- Set PART-HOLD-BACK to at least 3 x PART-TARGET in your EXT-X-SERVER-CONTROL tag.
- If you are targeting the lowest possible latency, reduce PART-TARGET rather than PART-HOLD-BACK.
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 "LL-HLS PART-HOLD-BACK is below three part durations" mean?
- In low-latency HLS, PART-HOLD-BACK tells the player how far behind the live edge to start. The specification requires it to be at least three times PART-TARGET.
- Why does it matter?
- Set too low, the player starts closer to the edge than the server can reliably serve. Every jitter in part production becomes a stall, so the stream rebuffers continuously on exactly the connections low latency was supposed to help.
- How do I fix it?
- 1. Set PART-HOLD-BACK to at least 3 x PART-TARGET in your EXT-X-SERVER-CONTROL tag. 2. If you are targeting the lowest possible latency, reduce PART-TARGET rather than PART-HOLD-BACK.
- 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.