matrix-js-sdk/src/webrtc/stats/trackStatsBuilder.ts

Matrix Client-Server SDK for Javascript

import { MediaTrackStats } from "./media/mediaTrackStats";
import { ValueFormatter } from "./valueFormatter";
import { TrackSummary } from "./callStatsReportSummary";

export class TrackStatsBuilder {
    public static buildFramerateResolution(trackStats: MediaTrackStats, now: any): void {
        const resolution = {
            height: now.frameHeight,
            width: now.frameWidth,
        };
        const frameRate = now.framesPerSecond;

        if (resolution.height && resolution.width) {
            trackStats.setResolution(resolution);
        }
        trackStats.setFramerate(Math.round(frameRate || 0));
    }

    public static calculateSimulcastFramerate(trackStats: MediaTrackStats, now: any, before: any, layer: number): void {
        let frameRate = trackStats.getFramerate();
        if (!frameRate) {
            if (before) {
                const timeMs = now.timestamp - before.timestamp;

                if (timeMs > 0 && now.framesSent) {
                    const numberOfFramesSinceBefore = now.framesSent - before.framesSent;

                    frameRate = (numberOfFramesSinceBefore / timeMs) * 1000;
                }
            }

            if (!frameRate) {
                return;
            }
        }

        // Reset frame rate to 0 when video is suspended as a result of endpoint falling out of last-n.
        frameRate = layer ? Math.round(frameRate / layer) : 0;
        trackStats.setFramerate(frameRate);
    }

    public static buildCodec(report: RTCStatsReport | undefined, trackStats: MediaTrackStats, now: any): void {
        const codec = report?.get(now.codecId);

        if (codec) {
            /**
             * The mime type has the following form: video/VP8 or audio/ISAC,
             * so we what to keep just the type after the '/', audio and video
             * keys will be added on the processing side.
             */
            const codecShortType = codec.mimeType.split("/")[1];

            codecShortType && trackStats.setCodec(codecShortType);
        }
    }

    public static buildBitrateReceived(trackStats: MediaTrackStats, now: any, before: any): void {
        trackStats.setBitrate({
            download: TrackStatsBuilder.calculateBitrate(
                now.bytesReceived,
                before.bytesReceived,
                now.timestamp,
                before.timestamp,
            ),
            upload: 0,
        });
    }

    public static buildBitrateSend(trackStats: MediaTrackStats, now: any, before: any): void {
        trackStats.setBitrate({
            download: 0,
            upload: this.calculateBitrate(now.bytesSent, before.bytesSent, now.timestamp, before.timestamp),
        });
    }

    public static buildPacketsLost(trackStats: MediaTrackStats, now: any, before: any): void {
        const key = now.type === "outbound-rtp" ? "packetsSent" : "packetsReceived";

        let packetsNow = now[key];
        if (!packetsNow || packetsNow < 0) {
            packetsNow = 0;
        }

        const packetsBefore = ValueFormatter.getNonNegativeValue(before[key]);
        const packetsDiff = Math.max(0, packetsNow - packetsBefore);

        const packetsLostNow = ValueFormatter.getNonNegativeValue(now.packetsLost);
        const packetsLostBefore = ValueFormatter.getNonNegativeValue(before.packetsLost);
        const packetsLostDiff = Math.max(0, packetsLostNow - packetsLostBefore);

        trackStats.setLoss({
            packetsTotal: packetsDiff + packetsLostDiff,
            packetsLost: packetsLostDiff,
            isDownloadStream: now.type !== "outbound-rtp",
        });
    }

    private static calculateBitrate(
        bytesNowAny: any,
        bytesBeforeAny: any,
        nowTimestamp: number,
        beforeTimestamp: number,
    ): number {
        const bytesNow = ValueFormatter.getNonNegativeValue(bytesNowAny);
        const bytesBefore = ValueFormatter.getNonNegativeValue(bytesBeforeAny);
        const bytesProcessed = Math.max(0, bytesNow - bytesBefore);

        const timeMs = nowTimestamp - beforeTimestamp;
        let bitrateKbps = 0;

        if (timeMs > 0) {
            bitrateKbps = Math.round((bytesProcessed * 8) / timeMs);
        }

        return bitrateKbps;
    }

    public static setTrackStatsState(trackStats: MediaTrackStats, transceiver: RTCRtpTransceiver | undefined): void {
        if (transceiver === undefined) {
            trackStats.alive = false;
            return;
        }

        const track = trackStats.getType() === "remote" ? transceiver.receiver.track : transceiver?.sender?.track;
        if (track === undefined || track === null) {
            trackStats.alive = false;
            return;
        }

        if (track.readyState === "ended") {
            trackStats.alive = false;
            return;
        }
        trackStats.muted = track.muted;
        trackStats.enabled = track.enabled;
        trackStats.alive = true;
    }

    public static buildTrackSummary(trackStatsList: MediaTrackStats[]): {
        audioTrackSummary: TrackSummary;
        videoTrackSummary: TrackSummary;
    } {
        const videoTrackSummary: TrackSummary = {
            count: 0,
            muted: 0,
            maxJitter: 0,
            maxPacketLoss: 0,
            concealedAudio: 0,
            totalAudio: 0,
        };
        const audioTrackSummary: TrackSummary = {
            count: 0,
            muted: 0,
            maxJitter: 0,
            maxPacketLoss: 0,
            concealedAudio: 0,
            totalAudio: 0,
        };

        const remoteTrackList = trackStatsList.filter((t) => t.getType() === "remote");
        const audioTrackList = remoteTrackList.filter((t) => t.kind === "audio");

        remoteTrackList.forEach((stats) => {
            const trackSummary = stats.kind === "video" ? videoTrackSummary : audioTrackSummary;
            trackSummary.count++;
            if (stats.alive && stats.muted) {
                trackSummary.muted++;
            }
            if (trackSummary.maxJitter < stats.getJitter()) {
                trackSummary.maxJitter = stats.getJitter();
            }
            if (trackSummary.maxPacketLoss < stats.getLoss().packetsLost) {
                trackSummary.maxPacketLoss = stats.getLoss().packetsLost;
            }
            if (audioTrackList.length > 0) {
                trackSummary.concealedAudio += stats.getAudioConcealment()?.concealedAudio;
                trackSummary.totalAudio += stats.getAudioConcealment()?.totalAudioDuration;
            }
        });

        return { audioTrackSummary, videoTrackSummary };
    }

    public static buildJitter(trackStats: MediaTrackStats, statsReport: any): void {
        if (statsReport.type !== "inbound-rtp") {
            return;
        }

        const jitterStr = statsReport?.jitter;
        if (jitterStr !== undefined) {
            const jitter = ValueFormatter.getNonNegativeValue(jitterStr);
            trackStats.setJitter(Math.round(jitter * 1000));
        } else {
            trackStats.setJitter(-1);
        }
    }

    public static buildAudioConcealment(trackStats: MediaTrackStats, statsReport: any): void {
        if (statsReport.type !== "inbound-rtp") {
            return;
        }
        const msPerSample = (1000 * statsReport?.totalSamplesDuration) / statsReport?.totalSamplesReceived;
        const concealedAudioDuration = msPerSample * statsReport?.concealedSamples;
        const totalAudioDuration = 1000 * statsReport?.totalSamplesDuration;
        trackStats.setAudioConcealment(concealedAudioDuration, totalAudioDuration);
    }
}