ts-sdp

ts-sdp is a library which allows for parsing, manipulation, and serialization of SDP.

Examples

Parsing

To parse an SDP string, just call the parse method.

const sdp = parse(sdpOffer);

Note: the given SDP string must terminate each line with either \r, \r\n or \n.

Manipulation

Once parsed, the SDP can be manipulated through its session and media block models. See the architecture overview for the model graph and ownership boundaries.

There are munging helper functions available in src/munge.ts. For example:

removeCodec(parsedSdp, 'vp8');
disableRtcpFbValue(parsedSdp, 'goog-remb');

Serialization

When done, the SDP can be serialized to a string like so:

const sdpStr = sdp.toString();

Grammar

The library currently contains much of the RFC 4566 grammar, in addition to some WebRTC-oriented attributes. Any lines without specific parser implementations are preserved by the internal unknown-line fallback.

The grammar is extendable to allow for parsing custom attributes. First, a subclass of Line must be defined:

class CustomLine extends Line {
  value: number;

  private static regex = /^foo:([0-9]+)$/;

  constructor(value: number) {
    super();
    this.value = value;
  }

  static fromSdpLine(line: string): CustomLine | undefined {
    if (!CustomLine.regex.test(line)) {
      return undefined;
    }

    const tokens = line.match(CustomLine.regex) as RegExpMatchArray;
    const value = parseInt(tokens[1], 10);
    return new CustomLine(value);
  }

  toSdpLine(): string {
    return `a=foo:${this.value}`;
  }
}

Then the parser must be added to the grammar under the appropriate LineType:

DefaultSdpGrammar.addParser('a', CustomLine.fromSdpLine);
// Result will contain a 'CustomLine' instance in whichever SdpBlock the attribute appears.
const result = parse(sdp);

Any implementation of Grammar can also be passed to the parse method:

class MyCustomGrammar extends Grammar {
  constructor() {
    super();
    this.addParser('a', CustomLine.fromSdpLine);
  }
}
const myGrammar = new MyCustomGrammar();
const result = parse('a=foo:42\n', myGrammar);

Contributing and AI-assisted development

• Read AGENTS.md for setup, verified commands, coding conventions, testing boundaries, and AI-agent guidance.
• Follow docs/contributing/GIT_CONVENTIONS.md for branch and commit conventions.
• Start with the knowledge base for parser, model, package, and release architecture.