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Migrating from hls.js 1.x to 1.4+

The 1.4 version of hls.js now ships with an ESM version of the library (dist/hls.mjs) which requires that you specify the workerPath config option in order for web workers to be used. This should point to the dist/hls.worker.js file included in the package.

If you are using the UMD version (dist/hls.js), no changes are required.

Important Notes:

  • If you are using a bundler, such as webpack, the ESM version of the package will likely be used by default. If this is the case, make sure to add the workerPath config option after upgrading to hls.js 1.4 or above.
  • Older web engines may experience severe performance degradation when using the ESM version of this package. If targeting older web engines, consider bundling your client application in loose mode to avoid additional function overhead. Alternatively, use the UMD/ES5 version of the package.

Migrating from hls.js 0.x to 1.x

This guide provides an overview to migrating an application using hls.js from v0.14.x to v1.0.0.

Dependencies

Promise support is now required. If your app requires support for older browsers that do not include support for Promises, include your own Promise polyfill.

Configuration Changes

Back Buffer Eviction

The new backBufferLength setting applies to Live and VOD streams. It defaults to Infinity, leaving back buffer eviction to the browser to perform on SourceBuffer append (https://www.w3.org/TR/media-source-2/#sourcebuffer-coded-frame-eviction). The demo page includes a setting of 90 seconds for demonstration purposes.

In v1.0 and up, the back buffer on VOD and Live content will be left up to the browser by default. Set backBufferLength to Infinity and liveBackBufferLength to 90 if you would like v1 to handle back buffer eviction for Live and VOD streams as older versions did. While liveBackBufferLength can still be used, it has been marked deprecated and may be removed in an upcoming minor release.

Front Buffer Eviction

The new frontBufferFlushThreshold setting defaults to Infinity seconds and governs active eviction of buffered ranges outside of the current contiguous front buffer. For example, given currentTime=0 and bufferedRanges=[[0, 100], [150, 200]] with a configured frontBufferFlushThreshold=60, we will only remove the range from [150, 200] as it lies outside of the target buffer length and is not contiguous with the forward buffer from the currentTime of 0.

Low Latency Streams

The new lowLatencyMode setting is enabled by default. Set to false to disable Low-latency part loading and target latency playback rate adjustment.

Chunked Transfer Support (experimental)

The new experimental progressive setting is disabled by default. Set it to true to stream and append audio and video data as it streams for each segment before segment load completion. Not recommended for production or small segments with only a single GoP or less.

Support for Group-Level Track Switching

  • hls.audioTracks and hls.subtitleTracks as well as AUDIO_TRACKS_UPDATED and SUBTITLE_TRACKS_UPDATED events only list tracks in the active level's audio/sub GROUP-ID after LEVEL_LOADING (this will go unnoticed for streams with no or only one group per track type)
    • The MANIFEST_PARSED event still reports all tracks when multiple GROUP-ID values are present. Applications that used that event to get tracks would need to be updated in v1 to switch to the corresponding track update events to select available tracks using the available indexes.
    • Track ids are no longer indexes of the complete list of audio or subtitle tracks. They are now indexes within each group. So six tracks in two groups that had ids 0,1,2,3,4,5 will now have ids 0,1,2,0,1,2. This allows for tracks to be changed by index/id within the range of available tracks as they were before.
  • Added groupId to audio and subtitle track loading and loaded events

Playback and Level Changes

  • Setting hls.currentLevel no longer pauses the media element while clearing the buffer and loading the new level. This can result in a stall error if playback doesn't start within a quarter of a second. Applications implementing manual quality switching with hls.currentLevel that do not want a stall reported should either pause or set video.playbackRate to 0 until the level switch is complete.

  • The maximum gap that will be jumped is now driven via the GapController MAX_START_GAP_JUMP. By default this value is set to two seconds, to match with the value that browsers will automatically skip when the autoplay attribute on the <video> element is set to true.

Event Changes

Event order and content have changed in some places. See Breaking Changes below, and please report any issues with breaking changes that impact your integrations

  • FRAG_LOADED fires after events handled on progress which can include everything up to appending a fragment if workers are disabled (more details below under Known Issues)
  • BUFFER_CODECS data has changed from { tracks: { video?, audio? } } to simply { video?, audio? }
  • BUFFER_APPENDING data has changed from { type, data, parent, content } to { type, data, frag, chunkMeta }
  • BUFFER_APPENDED data has changed
  • FRAG_DECRYPT_ERROR events are now surfaced as a FRAG_PARSING_ERROR along with other fragment transmuxing errors
  • Added additional error details to help identify the source of certain network error events:
    • SUBTITLE_LOAD_ERROR
    • SUBTITLE_TRACK_LOAD_TIMEOUT
    • UNKNOWN
  • Added additional error detail for streams that cannot start because source buffer(s) could not be created after parsing media codecs
    • BUFFER_INCOMPATIBLE_CODECS_ERROR will fire instead of BUFFER_CREATED with an empty tracks list. This media error is fatal and not recoverable. If you encounter this error make sure you include the correct CODECS string in your manifest, as this is most likely to occur when attempting to play a fragmented mp4 playlist with unknown codecs.
  • FRAG_LOAD_PROGRESS has been deprecated
  • FRAG_PARSING_DATA has been deprecated
  • STREAM_STATE_TRANSITION has been deprecated

Fragment Stats

  • The stats object has changed
    • trequest, tfirst, tload have been replaced by loading: HlsProgressivePerformanceTiming
    • tparsed has been replaced by parsing: HlsProgressivePerformanceTiming
  • On the Fragment object:
    • hasElementaryStream function has been removed
    • setElementaryStream and _elementaryStreams have been renamed (these are only for internal use)

LL-HLS Parts in events

  • FRAG____ events are now fired for LL-HLS part events with a part property that include the part details.

TypeScript

v0.x types are not compatible with v1.x. Type definitions are now exported with the build and npm package in dist/hls.d.ts and dist/hls.d.mts. Please use these type definitions if you are having trouble with DefinitelyTyped @types/hls.js and v1.x.