Hls.js: After changing level on initial load live stream with dvr starts at the middle

Created on 5 Oct 2016 · 3Comments · Source: video-dev/hls.js

Bug for hls.js

Environment

[x] The stream has correct Access-Control-Allow-Origin headers (CORS)
[x] There are no network errors such as 404s in the browser console when trying to play the stream
[x] The issue observed is not already reported by searching on Github under https://github.com/dailymotion/hls.js/issues
[x] The issue occurs in the latest reference client on http://dailymotion.github.io/hls.js/demo and not just on my page
Link to playable M3U8 file: http://edge-sgp-1.facecast.net/public/11234.m3u8
Hls.js version: 0.6.3 and 0.5.49
Browser name/version: Chrome 53, Firefox 48
OS name/version: Any

Steps to reproduce

Start live stream with dvr using a server that is far away (slow connection)
Hls.js will get the best playlist (e.g. source.m3u8) and the last chunk -> loading will be too slow and it will switch to the worse playlist (e.g. 160p.m3u8) but it will start playing from the middle chunk and not the last.

100% reproducible

Expected behavior

Stream will start at the last chunk

Actual behavior

Stream start at the middle chunk

Image of a bug

The weird thing is that I logged out levelDetails in _ensureFragmentAtLivePoint method of stream-controller.js file and it says for the 160p.m3u8 playlist that PTSKnown is true, however when you log out just the levelDetails.PTSKnown it is false. Maybe I don't understand something, but I don't see how local variable changes like that.

Console output

[log] > media source opened
[log] > manifest loaded,5 level(s) found, first bitrate:398860
[log] > startLoad
[log] > engine state transition from undefined to STOPPED
[log] > demuxing in webworker
[log] > engine state transition from STOPPED to STARTING
[log] > switching to level 4
[log] > (re)loading playlist for level 4
[log] > engine state transition from STARTING to WAITING_LEVEL
[log] > audio tracks updated
[log] > live playlist, reload in 1000 ms
[log] > level 4 loaded [0,10629],duration:53150.41311
[log] > live playlist - first load, unknown sliding
[log] > configure startPosition to 53132.41311
[log] > engine state transition from WAITING_LEVEL to IDLE
stream-controller.js:335 leveldetails: Object {type: null, version: 3, url: "http://edge-sgp-1.facecast.net/public/11209/source.m3u8", fragments: Array[10630], live: true…}
stream-controller.js:336 PTSKnown is false
[log] > Loading 10626 of [0 ,10629],level 4, currentTime:53132.41311,bufferEnd:53132.413
[log] > engine state transition from IDLE to FRAG_LOADING
[log] > fragLoadedDelay/bufferStarvationDelay/fragLevelNextLoadedDelay[3] :4.7/0.0/7.1
[log] > fragLoadedDelay/bufferStarvationDelay/fragLevelNextLoadedDelay[2] :4.7/0.0/5.3
[log] > fragLoadedDelay/bufferStarvationDelay/fragLevelNextLoadedDelay[1] :4.7/0.0/3.6
[log] > fragLoadedDelay/bufferStarvationDelay/fragLevelNextLoadedDelay[0] :4.7/0.0/2.3
[log] > switching to level 0
[log] > (re)loading playlist for level 0
[warn] > abort previous loader for type:level
[warn] > loading too slow, abort fragment loading and switch to level 0
[log] > engine state transition from FRAG_LOADING to IDLE
[log] > switching to level 0
[log] > (re)loading playlist for level 0
[warn] > playlist request ongoing
[log] > engine state transition from IDLE to WAITING_LEVEL
[log] > live playlist, reload in 1000 ms
[log] > level 0 loaded [0,10631],duration:53160.41311
[log] > live playlist - first load, unknown sliding
[log] > engine state transition from WAITING_LEVEL to IDLE
stream-controller.js:335 leveldetails: Object {type: null, version: 3, url: "http://edge-sgp-1.facecast.net/public/11209/160p.m3u8", fragments: Array[10632], live: true…}PTSKnown: true, averagetargetduration: 5.000038855342363, endSN: 10631, fragments: Array[10632], live: truestartSN: 0, targetduration: 6, tload: 15702.78, totalduration: 53160.41311, type: null, url: "http://edge-sgp-1.facecast.net/public/11209/160p.m3u8" }
stream-controller.js:336 PTSKnown is false
[log] > live playlist, switching playlist, unknown, load middle frag : 5316
[log] > Loading 5316 of [0 ,10631],level 0, currentTime:53132.41311,bufferEnd:53132.413
[warn] > abort previous fragment loader for type:main
[log] > engine state transition from IDLE to FRAG_LOADING
[log] > Loaded  5316 of level 0
[log] > engine state transition from FRAG_LOADING to PARSING

Bug

Source