/** * The copyright in this software is being made available under the BSD License, * included below. This software may be subject to other third party and contributor * rights, including patent rights, and no such rights are granted under this license. * * Copyright (c) 2017, Dash Industry Forum. * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation and/or * other materials provided with the distribution. * * Neither the name of Dash Industry Forum nor the names of its * contributors may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ import Constants from '../constants/Constants.js'; import FactoryMaker from '../../core/FactoryMaker.js'; import Debug from '../../core/Debug.js'; import {HTTPRequest} from '../vo/metrics/HTTPRequest.js'; import MediaPlayerEvents from '../MediaPlayerEvents.js'; import EventBus from '../../core/EventBus.js'; /** * Throughput generally stored in kbit/s * Latency generally stored in ms * @param {object} config * @constructor */ function ThroughputModel(config) { config = config || {}; const context = this.context; const debug = Debug(context).getInstance(); const settings = config.settings; const eventBus = EventBus(context).getInstance(); let throughputDict, latencyDict, ewmaThroughputDict, ewmaLatencyDict, ewmaHalfLife, logger; function setup() { logger = debug.getLogger(instance); ewmaHalfLife = { bandwidthHalfLife: { fast: settings.get().streaming.abr.throughput.ewma.throughputFastHalfLifeSeconds, slow: settings.get().streaming.abr.throughput.ewma.throughputSlowHalfLifeSeconds }, latencyHalfLife: { fast: settings.get().streaming.abr.throughput.ewma.latencyFastHalfLifeCount, slow: settings.get().streaming.abr.throughput.ewma.latencySlowHalfLifeCount } }; reset(); } /** * Use the provided request to add new entries for throughput and latency. Update the EWMA state as well. * @param {MediaType} mediaType * @param {object} httpRequest */ function addEntry(mediaType, httpRequest) { try { if (!mediaType || !httpRequest || !httpRequest.trace || !httpRequest.trace.length) { return; } _createSettingsForMediaType(mediaType); const latencyInMs = (httpRequest.tresponse.getTime() - httpRequest.trequest.getTime()) || 1; let throughputValues = _calculateThroughputValues(httpRequest, latencyInMs); throughputValues.latencyInMs = latencyInMs; if (isNaN(throughputValues.value) || !isFinite(throughputValues.value)) { return; } // Get estimated throughput (etp, in kbits/s) from CMSD response headers if (httpRequest.cmsd) { const etp = httpRequest.cmsd.dynamic && httpRequest.cmsd.dynamic.etp ? httpRequest.cmsd.dynamic.etp : null; if (etp) { // Apply weight ratio on etp const etpWeightRatio = settings.get().streaming.cmsd.abr.etpWeightRatio; if (etpWeightRatio > 0 && etpWeightRatio <= 1) { throughputValues.value = (throughputValues.value * (1 - etpWeightRatio)) + (etp * etpWeightRatio); } } } const cacheReferenceTime = (httpRequest._tfinish.getTime() - httpRequest.trequest.getTime()); if (_isCachedResponse(mediaType, cacheReferenceTime, httpRequest)) { logger.debug(`${mediaType} Assuming segment ${httpRequest.url} came from cache, ignoring it for throughput calculation`); return; } logger.debug(`Added throughput entry for ${mediaType}: ${throughputValues.value} kbit/s`) throughputValues.serviceLocation = httpRequest._serviceLocation; throughputDict[mediaType].push(throughputValues); latencyDict[mediaType].push({ value: latencyInMs }); _cleanupDict(mediaType); eventBus.trigger(MediaPlayerEvents.THROUGHPUT_MEASUREMENT_STORED, { throughputValues }) if (httpRequest.type !== HTTPRequest.MPD_TYPE) { _updateEwmaValues(ewmaThroughputDict[mediaType], throughputValues.value, settings.get().streaming.abr.throughput.ewma.weightDownloadTimeMultiplicationFactor * throughputValues.downloadTimeInMs, ewmaHalfLife.bandwidthHalfLife); _updateEwmaValues(ewmaLatencyDict[mediaType], latencyInMs, 1, ewmaHalfLife.latencyHalfLife); } } catch (e) { logger.error(e); } } /** * Returns the throughput in kbit/s , the download time in ms and the downloaded bytes for an HTTP request * @param {object} httpRequest * @param {number} latencyInMs * @return {object} * @private */ function _calculateThroughputValues(httpRequest, latencyInMs) { // Low latency is enabled, we used the fetch API and received chunks if (httpRequest._fileLoaderType && httpRequest._fileLoaderType === Constants.FILE_LOADER_TYPES.FETCH) { return _calculateThroughputValuesForFetch(httpRequest); } // Standard case, we used standard XHR requests else { return _calculateThroughputValuesForXhr(httpRequest, latencyInMs); } } /** * Calculates the throughput for requests using the Fetch API * @param {object} httpRequest * @param {number} latencyInMs * @return {number} * @private */ function _calculateThroughputValuesForFetch(httpRequest) { const downloadedBytes = httpRequest.trace.reduce((prev, curr) => prev + curr.b[0], 0); const downloadTimeInMs = httpRequest.trace.reduce((prev, curr) => prev + curr.d, 0); let throughputInKbit = NaN; if (settings.get().streaming.abr.throughput.useNetworkInformationApi.fetch) { throughputInKbit = _deriveThroughputFromNetworkApi() } if (isNaN(throughputInKbit)) { throughputInKbit = Math.round((8 * downloadedBytes) / downloadTimeInMs); // bits/ms = kbits/s } return { downloadedBytes, value: throughputInKbit, downloadTimeInMs }; } /** * Returns the throughput in kbit/s and the download time in ms for requests using XHR * @param {object} httpRequest * @param {number} latencyInMs * @return {object} * @private */ function _calculateThroughputValuesForXhr(httpRequest, latencyInMs) { let downloadedBytes = NaN; let downloadTimeInMs = NaN; let deriveThroughputViaResourceTimingApi = false; // Calculate the throughput using the ResourceTimingAPI if available if (settings.get().streaming.abr.throughput.useResourceTimingApi && httpRequest._resourceTimingValues) { downloadedBytes = httpRequest._resourceTimingValues.transferSize; downloadTimeInMs = httpRequest._resourceTimingValues.responseEnd - httpRequest._resourceTimingValues.responseStart; deriveThroughputViaResourceTimingApi = true; } // Use the standard throughput calculation if we can not use the Resource Timing API else { // We need at least two entries in the traces. The first entry includes the latency and the XHR progress event was thrown once bytes have already been received. // The second progress event can be set in relation to the first progress event and therefor gives us more accurate values if (httpRequest.trace.length <= 1) { return { throughput: NaN, downloadTimeInMs: NaN } } downloadedBytes = httpRequest.trace.reduce((prev, curr) => prev + curr.b[0], 0) - httpRequest.trace[0].b[0]; downloadTimeInMs = Math.max(httpRequest.trace.reduce((prev, curr) => prev + curr.d, 0) - httpRequest.trace[0].d, 1); } // If available and enabled use the Network Information API let throughputInKbit = NaN; if (!deriveThroughputViaResourceTimingApi && settings.get().streaming.abr.throughput.useNetworkInformationApi.xhr) { throughputInKbit = _deriveThroughputFromNetworkApi() } if (isNaN(throughputInKbit)) { const referenceTimeInMs = settings.get().streaming.abr.throughput.useDeadTimeLatency ? downloadTimeInMs : downloadTimeInMs + latencyInMs; throughputInKbit = Math.round((8 * downloadedBytes) / referenceTimeInMs) // bits/ms = kbits/s } return { downloadedBytes, value: throughputInKbit, downloadTimeInMs }; } /** * Return the current estimated bandwidth based on NetworkInformation.downlink if the API is available * @returns {*|number} * @private */ function _deriveThroughputFromNetworkApi() { // NetworkInformation.downlink: Returns the effective bandwidth estimate in megabits per second, rounded to the nearest multiple of 25 kilobits per seconds. if (navigator && navigator.connection && !isNaN(navigator.connection.downlink) && navigator.connection.downlink > 0) { return navigator.connection.downlink * 1000 } return NaN } /** * Check if the response was cached. * @param {MediaType} mediaType * @param {number} cacheReferenceTime * @param {object} httpRequest * @return {boolean} * @private */ function _isCachedResponse(mediaType, cacheReferenceTime, httpRequest) { if (settings.get().streaming.abr.throughput.useResourceTimingApi && httpRequest._resourceTimingValues) { return httpRequest._resourceTimingValues.transferSize === 0 && httpRequest._resourceTimingValues.decodedBodySize > 0 } if (isNaN(cacheReferenceTime)) { return false; } if (mediaType === Constants.VIDEO) { return cacheReferenceTime < settings.get().streaming.cacheLoadThresholds[Constants.VIDEO]; } else if (mediaType === Constants.AUDIO) { return cacheReferenceTime < settings.get().streaming.cacheLoadThresholds[Constants.AUDIO]; } } /** * * @param {object} ewmaObj * @param {number} value * @param {number} weight * @param {object} halfLife * @private */ function _updateEwmaValues(ewmaObj, value, weight, halfLife) { // Note about startup: // Estimates start at 0, so early values are underestimated. // This effect is countered in getAverageEwma() by dividing the estimates by: // 1 - Math.pow(0.5, ewmaObj.totalWeight / halfLife) const fastAlpha = Math.pow(0.5, weight / halfLife.fast); ewmaObj.fastEstimate = (1 - fastAlpha) * value + fastAlpha * ewmaObj.fastEstimate; const slowAlpha = Math.pow(0.5, weight / halfLife.slow); ewmaObj.slowEstimate = (1 - slowAlpha) * value + slowAlpha * ewmaObj.slowEstimate; ewmaObj.totalWeight += weight; } /** * Shift old entries once we reached the threshold * @param {MediaType} mediaType * @private */ function _cleanupDict(mediaType) { if (throughputDict[mediaType].length > settings.get().streaming.abr.throughput.sampleSettings.maxMeasurementsToKeep) { throughputDict[mediaType].shift(); } if (latencyDict[mediaType].length > settings.get().streaming.abr.throughput.sampleSettings.maxMeasurementsToKeep) { latencyDict[mediaType].shift(); } } /** * Setup the dict objects for a specific media type * @param mediaType * @private */ function _createSettingsForMediaType(mediaType) { throughputDict[mediaType] = throughputDict[mediaType] || []; latencyDict[mediaType] = latencyDict[mediaType] || []; ewmaThroughputDict[mediaType] = ewmaThroughputDict[mediaType] || { fastEstimate: 0, slowEstimate: 0, totalWeight: 0 }; ewmaLatencyDict[mediaType] = ewmaLatencyDict[mediaType] || { fastEstimate: 0, slowEstimate: 0, totalWeight: 0 }; } function getThroughputDict(mediaType) { if (!mediaType) { return throughputDict } return throughputDict[mediaType]; } function getEwmaThroughputDict(mediaType) { if (!mediaType) { return ewmaThroughputDict } return ewmaThroughputDict[mediaType] } function getLatencyDict(mediaType) { if (!mediaType) { return latencyDict } return latencyDict[mediaType]; } function getEwmaLatencyDict(mediaType) { if (!mediaType) { return ewmaLatencyDict } return ewmaLatencyDict[mediaType]; } function getEwmaHalfLife() { return ewmaHalfLife; } /** * Reset all values */ function reset() { throughputDict = {}; latencyDict = {}; ewmaThroughputDict = {}; ewmaLatencyDict = {}; } const instance = { addEntry, getThroughputDict, getEwmaThroughputDict, getEwmaLatencyDict, getEwmaHalfLife, getLatencyDict, reset }; setup(); return instance; } ThroughputModel.__dashjs_factory_name = 'ThroughputModel'; export default FactoryMaker.getClassFactory(ThroughputModel);