@bengreenier/krtp/dist/Control.js

Node implementation of rdp protocol. RFC 3550

"use strict";
/*
 * +===============================================
 * | Author:        Parham Alvani (parham.alvani@gmail.com)
 * |
 * | Creation Date: 03-06-2017
 * |
 * | File Name:     Control.ts
 * +===============================================
 */
Object.defineProperty(exports, "__esModule", { value: true });
/**
 * ControlSR implements sender report message of real-time control protocol.
 * The sender report is sent periodically by the active senders in a conference to report transmission
 * and reception statistics for all RTP packets sent during the interval.
 */
class ControlSR {
    constructor(packetCount, octetCount, ssrc, timestamp, ntpTimestamp = Date.now()) {
        this.rc = 0; // Reception report count
        this.packetCount = packetCount;
        this.octetCount = octetCount;
        this.ssrc = ssrc;
        this.timestamp = timestamp;
        this.ntpTimestamp = ntpTimestamp;
    }
    static deserialize(buff) {
        // header
        // buff[0] = (V << 6 | P << 5 | RC)
        if ((buff[0] & (0xc0 >> 6)) !== 2) {
            throw new Error("Invalid RTCP packet");
        }
        // buff[1] = PT
        if (buff[1] !== 200) {
            throw new Error("Invalid RTCP packet");
        }
        // buff[2, 3] = length
        const length = (buff.readUInt16BE(2) + 1) * 4;
        if (buff.length !== length) {
            throw new Error("Invalid RTCP packet");
        }
        // buff[4, 5, 6, 7] = SSRC
        const ssrc = buff.readUInt32BE(4);
        // sender info
        // buff[8, 9, 10, 11] = ntpTS
        // buff[12, 13, 14, 15] = ntpTS
        const ntpTimestamp = buff.readUInt32BE(8) * 1000 + buff.readUInt32BE(12);
        // buff[16, 17, 18, 19] = TS
        const timestamp = buff.readUInt32BE(16);
        // buff[20, 21, 22, 23] = packetCount
        const packetCount = buff.readUInt32BE(20);
        // buff[24, 25, 26, 27] = octetCount
        const octetCount = buff.readUInt32BE(24);
        return new ControlSR(packetCount, octetCount, ssrc, timestamp, ntpTimestamp);
    }
    serialize() {
        const buff = Buffer.alloc(8 + 20);
        // header
        // buff[0] = (V << 6 | P << 5 | RC)
        buff[0] = (2 << 6) | (0 << 5) | this.rc;
        // buff[1] = PT
        // Sender Report Packet Type
        buff[1] = 200;
        // buff[2, 3] = length
        buff.writeUInt16BE(((buff.length / 4) | 0) - 1, 2);
        // buff[4, 5, 6, 7] = SSRC
        buff.writeUInt32BE(this.ssrc, 4);
        // sender info
        // buff[8, 9, 10, 11] = ntpTS
        buff.writeUInt32BE((this.ntpTimestamp / 1000) | 0, 8);
        // buff[12, 13, 14, 15] = ntpTS
        buff.writeUInt32BE(this.ntpTimestamp % 1000, 12);
        // buff[16, 17, 18, 19] = TS
        buff.writeUInt32BE(this.timestamp, 16);
        // buff[20, 21, 22, 23] = packetCount
        buff.writeUInt32BE(this.packetCount, 20);
        // buff[24, 25, 26, 27] = octetCount
        buff.writeUInt32BE(this.octetCount, 24);
        return buff;
    }
}
exports.ControlSR = ControlSR;