HLS rendition group has an ambiguous default
A group has no DEFAULT rendition, or more than one, so which track plays at start-up is left to the player.
What it means
Within one GROUP-ID, at most one EXT-X-MEDIA entry may carry DEFAULT=YES. An audio group should carry exactly one; more than one is invalid.
Why it matters
The default is the track a viewer gets before choosing anything. With none, players fall back to their own heuristics — often the first entry, sometimes the device language — so the same stream starts in different languages on different devices. With two, behaviour is simply undefined.
How to fix it
- Mark exactly one rendition per audio group DEFAULT=YES.
- Subtitles are the exception: a group with no default means subtitles start off, which is usually what you want.
- Set AUTOSELECT=YES on renditions a player may switch to based on the viewer’s system language.
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 rendition group has an ambiguous default" mean?
- Within one GROUP-ID, at most one EXT-X-MEDIA entry may carry DEFAULT=YES. An audio group should carry exactly one; more than one is invalid.
- Why does it matter?
- The default is the track a viewer gets before choosing anything. With none, players fall back to their own heuristics — often the first entry, sometimes the device language — so the same stream starts in different languages on different devices. With two, behaviour is simply undefined.
- How do I fix it?
- 1. Mark exactly one rendition per audio group DEFAULT=YES. 2. Subtitles are the exception: a group with no default means subtitles start off, which is usually what you want. 3. Set AUTOSELECT=YES on renditions a player may switch to based on the viewer’s system language.
- How do I check an HLS playlist for this automatically?
- Paste the master or media playlist URL into the free HLS analyzer. It runs this check on every analysis alongside the ladder, timing and live-edge audits, and links each finding back to the page that explains it.
- What is the first thing to try?
- Mark exactly one rendition per audio group DEFAULT=YES.
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.