flv.js API

This document use TypeScript-like definitions to describe interfaces.


flv.js exports all the interfaces through flvjs object which exposed in global context window.

flvjs object can also be accessed by require or ES6 import.





function createPlayer(mediaDataSource: MediaDataSource, config?: Config): Player;

Create a player instance according to type field indicated in mediaDataSource, with optional config.


Field Type Description
type string Indicates media type, 'flv' or 'mp4'
isLive? boolean Indicates whether the data source is a live stream
cors? boolean Indicates whether to enable CORS for http fetching
withCredentials? boolean Indicates whether to do http fetching with cookies
hasAudio? boolean Indicates whether the stream has audio track
hasVideo? boolean Indicates whether the stream has video track
duration? number Indicates total media duration, in milliseconds
filesize? number Indicates total file size of media file, in bytes
url? string Indicates media URL, can be starts with 'https(s)' or 'ws(s)' (WebSocket)
segments? Array<MediaSegment> Optional field for multipart playback, see MediaSegment

If segments field exists, transmuxer will treat this MediaDataSource as a multipart source.

In multipart mode, duration filesize url field in MediaDataSource structure will be ignored.


Field Type Description
duration number Required field, indicates segment duration in milliseconds
filesize? number Optional field, indicates segment file size in bytes
url string Required field, indicates segment file URL


Field Type Default Description
enableWorker? boolean false Enable separated thread for transmuxing (unstable for now)
enableStashBuffer? boolean true Enable IO stash buffer. Set to false if you need realtime (minimal latency) for live stream playback, but may stalled if there’s network jittering.
stashInitialSize? number 384KB Indicates IO stash buffer initial size. Default is 384KB. Indicate a suitable size can improve video load/seek time.
isLive? boolean false Same to isLive in MediaDataSource, ignored if has been set in MediaDataSource structure.
lazyLoad? boolean true Abort the http connection if there’s enough data for playback.
lazyLoadMaxDuration? number 3 * 60 Indicates how many seconds of data to be kept for lazyLoad.
lazyLoadRecoverDuration? number 30 Indicates the lazyLoad recover time boundary in seconds.
deferLoadAfterSourceOpen? boolean true Do load after MediaSource sourceopen event triggered. On Chrome, tabs which be opened in background may not trigger sourceopen event until switched to that tab.
autoCleanupSourceBuffer boolean false Do auto cleanup for SourceBuffer
autoCleanupMaxBackwardDuration number 3 * 60 When backward buffer duration exceeded this value (in seconds), do auto cleanup for SourceBuffer
autoCleanupMinBackwardDuration number 2 * 60 Indicates the duration in seconds to reserve for backward buffer when doing auto cleanup.
fixAudioTimestampGap boolean true Fill silent audio frames to avoid a/v unsync when detect large audio timestamp gap.
accurateSeek? boolean false Accurate seek to any frame, not limited to video IDR frame, but may a bit slower. Available on Chrome > 50, FireFox and Safari.
seekType? string 'range' 'range' use range request to seek, or 'param' add params into url to indicate request range.
seekParamStart? string 'bstart' Indicates seek start parameter name for seekType = 'param'
seekParamEnd? string 'bend' Indicates seek end parameter name for seekType = 'param'
rangeLoadZeroStart? boolean false Send Range: bytes=0- for first time load if use Range seek
customSeekHandler? object undefined Indicates a custom seek handler
reuseRedirectedURL? boolean false Reuse 301/302 redirected url for subsequence request like seek, reconnect, etc.
referrerPolicy? string no-referrer-when-downgrade Indicates the Referrer Policy when using FetchStreamLoader


function isSupported(): boolean;

Return true if basic playback can works on your browser.


function getFeatureList(): FeatureList;

Return a FeatureList object which has following details:


| Field | Type | Description | | ———————– | ——— | —————————————- | | mseFlvPlayback | boolean | Same to flvjs.isSupported(), indicates whether basic playback works on your browser. | | mseLiveFlvPlayback | boolean | Indicates whether HTTP FLV live stream can works on your browser. | | networkStreamIO | boolean | Indicates whether the network loader is streaming. | | networkLoaderName | string | Indicates the network loader type name. | | nativeMP4H264Playback | boolean | Indicates whether your browser support H.264 MP4 video file natively. | | nativeWebmVP8Playback | boolean | Indicates whether your browser support WebM VP8 video file natively. | | nativeWebmVP9Playback | boolean | Indicates whether your browser support WebM VP9 video file natively. |


interface FlvPlayer extends Player {}

FLV player which implements the Player interface. Can be created by new operator directly.


interface NativePlayer extends Player {}

Player wrapper for browser’s native player (HTMLVideoElement) without MediaSource src, which implements the Player interface. Useful for singlepart MP4 file playback.

interface Player (abstract)

interface Player {
    constructor(mediaDataSource: MediaDataSource, config?: Config): Player;
    destroy(): void;
    on(event: string, listener: Function): void;
    off(event: string, listener: Function): void;
    attachMediaElement(mediaElement: HTMLMediaElement): void;
    detachMediaElement(): void;
    load(): void;
    unload(): void;
    play(): Promise<void>;
    pause(): void;
    type: string;
    buffered: TimeRanges;
    duration: number;
    volume: number;
    muted: boolean;
    currentTime: number;
    mediaInfo: Object;
    statisticsInfo: Object;


A global interface which include several static getter/setter to set flv.js logcat verbose level.

interface LoggingControl {
    forceGlobalTag: boolean;
    globalTag: string;
    enableAll: boolean;
    enableDebug: boolean;
    enableVerbose: boolean;
    enableInfo: boolean;
    enableWarn: boolean;
    enableError: boolean;
    getConfig(): Object;
    applyConfig(config: Object): void;
    addLogListener(listener: Function): void;
    removeLogListener(listener: Function): void;


A series of constants that can be used with Player.on() / Player.off(). They require the prefix flvjs.Events.

Event Description
ERROR An error occurred by any cause during the playback
LOADING_COMPLETE The input MediaDataSource has been completely buffered to end
RECOVERED_EARLY_EOF An unexpected network EOF occurred during buffering but automatically recovered
MEDIA_INFO Provides technical information of the media like video/audio codec, bitrate, etc.
STATISTICS_INFO Provides playback statistics information like dropped frames, current speed, etc.


The possible errors that can come up during playback. They require the prefix flvjs.ErrorTypes.

Error Description
NETWORK_ERROR Errors related to the network
MEDIA_ERROR Errors related to the media (format error, decode issue, etc)
OTHER_ERROR Any other unspecified error


Provide more verbose explanation for Network and Media errors. They require the prefix flvjs.ErrorDetails.

Error Description
NETWORK_EXCEPTION Related to any other issues with the network; contains a message
NETWORK_STATUS_CODE_INVALID Related to an invalid HTTP status code, such as 403, 404, etc.
NETWORK_TIMEOUT Related to timeout request issues
NETWORK_UNRECOVERABLE_EARLY_EOF Related to unexpected network EOF which cannot be recovered
MEDIA_MSE_ERROR Related to MediaSource’s error such as decode issue
MEDIA_FORMAT_ERROR Related to any invalid parameters in the media stream
MEDIA_FORMAT_UNSUPPORTED The input MediaDataSource format is not supported by flv.js
MEDIA_CODEC_UNSUPPORTED The media stream contains video/audio codec which is not supported