ts-sdp

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

$3

##### Parsing
To parse an SDP string, just call the parse method.
``typescript
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. The model of the parsed object is as follows:
!image

There are munging helper functions available in the munge.ts file. For example:
`typescript
removeCodec(parsedSdp, 'vp8');
disableRtcpFbValue(parsedSdp, 'goog-remb');
`
Manipulation can also be done manually:
`typescript
TODO: more examples
`

##### Serialization
When done, the SDP can be serialized to a string like so:
`typescript
const sdpStr = sdp.toString();
`

#### Grammar
The library currently contains much of the RGC4566 grammar, in addition to some additional attributes. Any lines without specific parser implementations are still parsed via the UnknownLine type.

The grammar is extendable to allow for parsing custom attributes. First, a subclass of Line must be defined:
`typescript
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:
`typescript
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:
`typescript
class MyCustomGrammar extends Grammar {
...
}
const myGrammar = new MyCustomGrammar();
const result = parse(sdp, myGrammar);
``