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The Metadata class is the primary descriptor for a WebRTS stream. It is received via the onMetadata callback on Player or Source, and carries everything needed to configure playback: the protocol version negotiated with the server, the current live time, the full set of available tracks (audio, video, and data), and any DRM/content-protection configuration. Use the track arrays and filter methods to select the right quality level and codec before playback begins. 
import { Metadata } from '@ceeblue/wrts-client';

​
Constructor

​
obj
any
A parsed JSON manifest object from the WRTS endpoint. The constructor reads the following fields:
  • version — protocol version string (e.g. "1.2.3") or number
  • currentTime / liveTime — current live time in milliseconds (or seconds if a decimal is present; automatically converted)
  • tracks[] — array of track descriptor objects
  • contentProtection[] — array of DRM descriptors keyed by KID

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Static Methods

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Metadata.connect
static async method
Fetches the stream manifest from a WRTS endpoint and returns a populated Metadata instance. The live time is adjusted by half the round-trip time (RTT) of the fetch to compensate for network latency.
static async connect(
  params: Connect.Params,
  controller: AbortController
): Promise<Metadata>
Returns Promise<Metadata> — resolves to the parsed metadata object.
const controller = new AbortController();
const metadata = await Metadata.connect({ endPoint: 'https://example.com/stream' }, controller);
console.log('Protocol:', metadata.protocolVersion);

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Properties

​
protocolVersion
{ major: number; minor: number; patch: number }
The WebRTS protocol version negotiated by the server, parsed from the version field of the manifest.
// Example: { major: 1, minor: 2, patch: 0 }
console.log(metadata.protocolVersion.major);
​
date
Date
The Date at which this Metadata instance was constructed. Useful for calculating the age of cached metadata.
​
liveTime
number
The current live time of the stream, in milliseconds. This value continuously advances using the wall clock — it stores the timestamp from the manifest and extrapolates forward based on elapsed time since the object was created. The setter records both the new value and the current wall-clock time so future reads extrapolate correctly.
console.log('Current live time:', metadata.liveTime, 'ms');
​
tracks
Map<number, MediaTrack>
All tracks indexed by their numeric track ID, sorted by descending bandwidth. Includes audio, video, and data tracks.
​
audioTracks
Array<MediaTrack>
Audio-only tracks, sorted in descending order of bandwidth. The first element is the highest-quality audio track.
​
videoTracks
Array<MediaTrack>
Video-only tracks, sorted in descending order of bandwidth. The first element is the highest-quality video track.
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dataTracks
Array<MediaTrack>
Data and subtitle tracks. Not sorted by bandwidth.
​
contentProtection
Map<string, ContentProtection>
DRM settings keyed by KID (Key ID). Each key is a 32-character lowercase hex string. Values are ContentProtection objects describing the encryption scheme, IV, and PSSH boxes for each DRM system.

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Methods

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fix()
method
Deduplicates and re-sorts all tracks by descending bandwidth, then rebuilds the up/down linked-list pointers on each MediaTrack. Call this after manually inserting tracks into Metadata outside of the constructor.
metadata.fix();
​
filterAudios(codecs?)
method
Removes all audio tracks whose codec is not in the provided set. Repairs up/down pointers afterward.
filterAudios(codecs?: Array<Media.Codec>): this
Returns this — chainable.
​
filterVideos(codecs?)
method
Removes all video tracks whose codec is not in the provided set. Repairs up/down pointers afterward.
filterVideos(codecs?: Array<Media.Codec>): this
Returns this — chainable.
​
filterDatas(codecs?)
method
Removes all data/subtitle tracks whose codec is not in the provided set.
filterDatas(codecs?: Array<Media.Codec>): this
Returns this — chainable.

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MediaTrack Properties

Each entry in tracks, audioTracks, videoTracks, and dataTracks is a MediaTrack instance. See the Media Types page for the full class reference. Key properties are:
​
id
number
Numeric track identifier. Matches the key used in Metadata.tracks.
​
type
Media.Type
Track type: Media.Type.AUDIO, Media.Type.VIDEO, or Media.Type.DATA.
​
codec
Media.Codec
Detected codec enum value, e.g. Media.Codec.H264, Media.Codec.AAC, Media.Codec.OPUS.
​
codecString
string
RFC 6381 codec descriptor string (e.g. "avc1.640028", "mp4a.40.2").
​
bandwidth
number
Maximum bandwidth in bytes per second (Bps). Used for sorting and ABR decisions.
​
rate
number
Sample rate in Hz for audio tracks (e.g. 48000), or frames per second for video tracks (e.g. 25).
​
resolution
Media.Resolution | undefined
{ width: number, height: number } — only meaningful for video tracks. Defaults to { width: 0, height: 0 }.
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channels
number
Number of audio channels. Only meaningful for audio tracks.
​
language
string | undefined
ISO 639-2 language code (e.g. "eng", "fra"). Present on audio and subtitle/data tracks when provided by the server.
​
config
Uint8Array | undefined
Codec-specific initialization data (e.g. avcC, esds, dOps box contents). Required for initializing MSE SourceBuffer codec strings.
​
contentProtection
string | undefined
The KID string linking this track to a ContentProtection entry in Metadata.contentProtection.
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up
MediaTrack | undefined
The next-higher-quality track of the same type in the sorted linked list. undefined if this is the highest-quality track.
​
down
MediaTrack | undefined
The next-lower-quality track of the same type in the sorted linked list. undefined if this is the lowest-quality track.

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ContentProtection Type

ContentProtection objects are stored in Metadata.contentProtection, keyed by KID.
​
scheme
ProtectionScheme
The CENC protection scheme applied to encrypted samples.
ValueHexDescription
ProtectionScheme.CENC0x63656e63AES-CTR full-sample encryption
ProtectionScheme.CBC10x63626331AES-CBC full-sample encryption
ProtectionScheme.CENS0x63656e73AES-CTR with sub-sample pattern
ProtectionScheme.CBCS0x63626373AES-CBC with sub-sample pattern (default)
​
kid
string
The Key ID as a 32-character lowercase hex string (UUID without dashes).
​
iv
string | undefined
The initialization vector as a hex string. undefined when ivMode is 'sample' (each sample carries its own IV).
​
ivMode
'constant' | 'sample'
How the IV is delivered:
  • 'constant' — a single IV is reused for every sample, carried in the metadata
  • 'sample' — each sample’s Media.Sample.iv field carries a per-sample IV
​
pssh
Map<string, string>
Maps DRM system UUID (e.g. "edef8ba9-79d6-4ace-a3c8-27dcd51d21ed" for Widevine) to the base64-encoded PSSH box for that system.

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Usage Example

player.onMetadata = (metadata) => {
  console.log('Protocol version:', metadata.protocolVersion);
  console.log(
    'Video tracks:',
    metadata.videoTracks.map(t => `${t.id}: ${t.bandwidth}bps`)
  );

  // Select the highest-quality video track and first audio track:
  return {
    video: metadata.videoTracks[0]?.id,
    audio: metadata.audioTracks[0]?.id
  };
};
Use filterVideos and filterAudios before returning the track selection to ensure only browser-supported codecs are passed to the player. For example:
metadata.filterVideos([Media.Codec.H264]).filterAudios([Media.Codec.AAC, Media.Codec.OPUS]);

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