import { createRequire } from "module";
import { Codec } from "./types.js";
const require = createRequire(import.meta.url);
const g711 = require("g711");
/**
* Base class for G.711 codecs (PCMU and PCMA)
* Maintains backward compatibility with existing implementation
*/
abstract class G711Codec implements Codec {
abstract readonly payloadType: number;
abstract readonly name: string;
readonly sampleRate = 8000;
readonly clockRate = 8000;
public encode(pcm: Int16Array): Buffer {
throw new Error("Subclass must implement encode");
}
public decode(encoded: Buffer): Int16Array {
throw new Error("Subclass must implement decode");
}
protected pcmToUlaw(pcm: Int16Array): Buffer {
const encoded = g711.ulawFromPCM(pcm);
return Buffer.from(encoded);
}
protected ulawToPcm(encoded: Buffer): Int16Array {
const decoded = g711.ulawToPCM(encoded);
return new Int16Array(decoded.buffer, decoded.byteOffset, decoded.byteLength / 2);
}
protected pcmToAlaw(pcm: Int16Array): Buffer {
const encoded = g711.alawFromPCM(pcm);
return Buffer.from(encoded);
}
protected alawToPcm(encoded: Buffer): Int16Array {
const decoded = g711.alawToPCM(encoded);
return new Int16Array(decoded.buffer, decoded.byteOffset, decoded.byteLength / 2);
}
}
/**
* PCMU (μ-law) Codec - G.711
* Payload type 0, 8kHz sample rate
*/
export class PCMUCodec extends G711Codec {
readonly payloadType = 0;
readonly name = "PCMU";
encode(pcm: Int16Array): Buffer {
return this.pcmToUlaw(pcm);
}
decode(encoded: Buffer): Int16Array {
return this.ulawToPcm(encoded);
}
}
/**
* PCMA (A-law) Codec - G.711
* Payload type 8, 8kHz sample rate
*/
export class PCMACodec extends G711Codec {
readonly payloadType = 8;
readonly name = "PCMA";
encode(pcm: Int16Array): Buffer {
return this.pcmToAlaw(pcm);
}
decode(encoded: Buffer): Int16Array {
return this.alawToPcm(encoded);
}
}
