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* 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) 2013, 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 FactoryMaker from '../../core/FactoryMaker.js';
import Settings from '../../core/Settings.js';
import Constants from '../constants/Constants.js';
import Debug from '../../core/Debug.js';
/**
* @module FetchLoader
* @ignore
* @description Manages download of resources via HTTP using fetch.
*/
function FetchLoader() {
const context = this.context;
const settings = Settings(context).getInstance();
let instance, boxParser, logger;
function setConfig(cfg) {
boxParser = cfg.boxParser
}
function setup() {
logger = Debug(context).getInstance().getLogger(instance);
}
/**
* Load request
* With HTTP responses that use chunked transfer encoding, the promise returned by fetch will resolve as soon as the response's headers are received.
* @param {CommonMediaRequest} commonMediaRequest
* @param {CommonMediaResponse} commonMediaResponse
*/
function load(commonMediaRequest, commonMediaResponse) {
const headers = _getHeaders(commonMediaRequest);
const abortController = _setupAbortMechanism(commonMediaRequest);
const fetchResourceRequestObject = _getFetchResourceRequestObject(commonMediaRequest, headers, abortController);
fetch(fetchResourceRequestObject)
.then((fetchResponse) => {
_handleFetchResponse(fetchResponse, commonMediaRequest, commonMediaResponse);
})
.catch(() => {
_handleFetchError(commonMediaRequest);
})
}
function _handleFetchResponse(fetchResponse, commonMediaRequest, commonMediaResponse) {
_updateCommonMediaResponseInstance(commonMediaResponse, fetchResponse);
if (!fetchResponse.ok) {
commonMediaRequest.customData.onloadend();
}
let totalBytesReceived = 0;
let signaledFirstByte = false;
let receivedData = new Uint8Array();
let endPositionOfLastProcessedBoxInReceivedData = 0;
commonMediaRequest.customData.reader = fetchResponse.body.getReader();
let downloadedData = [];
let moofStartTimeData = [];
let mdatEndTimeData = [];
let lastChunkWasFinished = true;
const calculationMode = settings.get().streaming.abr.throughput.lowLatencyDownloadTimeCalculationMode;
/**
* Callback function for ReadableStreamDefaultReader
* @param value - chunk data. Always undefined when done is true.
* @param done - true if the stream has already given you all its data.
*/
const _processResult = ({ value, done }) => {
if (done) {
_handleRequestComplete()
return;
}
if (value && value.length > 0) {
_handleReceivedChunkData(value)
}
_readResponseBody(commonMediaRequest, commonMediaResponse, _processResult);
};
/**
* Once a request is completed throw final progress event with the calculated bytes and download time
* @private
*/
function _handleRequestComplete() {
if (receivedData) {
const calculatedDownloadTime = _calculateDownloadTime();
// In this case we push an entry to the traces.
// This is the only entry we push as the other calls to onprogress use noTrace = true
commonMediaRequest.customData.onprogress({
loaded: totalBytesReceived,
total: totalBytesReceived,
lengthComputable: true,
time: calculatedDownloadTime
});
commonMediaResponse.data = receivedData.buffer;
}
commonMediaRequest.customData.onloadend();
}
function _calculateDownloadTime() {
// If there is pending data, call progress so network metrics
// are correctly generated
// Same structure as https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequestEventTarget/
let downloadTime = null;
if (calculationMode === Constants.LOW_LATENCY_DOWNLOAD_TIME_CALCULATION_MODE.MOOF_PARSING) {
downloadTime = _getDownloadTimeForMoofParsing();
} else if (calculationMode === Constants.LOW_LATENCY_DOWNLOAD_TIME_CALCULATION_MODE.DOWNLOADED_DATA) {
downloadTime = _getDownloadTimeForDownloadedData()
}
return downloadTime;
}
function _getDownloadTimeForMoofParsing() {
const calculatedThroughput = _calculateThroughputByMoofMdatTimes(moofStartTimeData, mdatEndTimeData);
if (calculatedThroughput) {
return totalBytesReceived * 8 / calculatedThroughput;
}
return null;
}
function _getDownloadTimeForDownloadedData() {
return calculateDownloadedTime(downloadedData, totalBytesReceived);
}
/**
* Called every time we received data if the request is not completed
* @param value
* @private
*/
function _handleReceivedChunkData(value) {
receivedData = _concatTypedArray(receivedData, value);
totalBytesReceived += value.length;
downloadedData.push({
timestamp: _getCurrentTimestamp(),
bytes: value.length
});
if (calculationMode === Constants.LOW_LATENCY_DOWNLOAD_TIME_CALCULATION_MODE.MOOF_PARSING && lastChunkWasFinished) {
_findMoofBoxInChunkData();
}
const boxesInfo = boxParser.findLastTopIsoBoxCompleted(['moov', 'mdat'], receivedData, endPositionOfLastProcessedBoxInReceivedData);
if (boxesInfo.found) {
_handleTopIsoBoxCompleted(boxesInfo);
} else {
_handleNoCompletedTopIsoBox(boxesInfo);
}
}
function _findMoofBoxInChunkData() {
const boxesInfo = boxParser.findLastTopIsoBoxCompleted(['moof'], receivedData, endPositionOfLastProcessedBoxInReceivedData);
if (boxesInfo.found) {
lastChunkWasFinished = false;
moofStartTimeData.push({
timestamp: _getCurrentTimestamp()
});
}
}
function _handleTopIsoBoxCompleted(boxesInfo) {
const endPositionOfLastTargetBox = boxesInfo.startOffsetOfLastFoundTargetBox + boxesInfo.sizeOfLastFoundTargetBox;
const data = _getDataForMediaSourceBufferAndAdjustReceivedData(endPositionOfLastTargetBox);
// Store the end time of each chunk download with its size in array EndTimeData
if (calculationMode === Constants.LOW_LATENCY_DOWNLOAD_TIME_CALCULATION_MODE.MOOF_PARSING && !lastChunkWasFinished) {
lastChunkWasFinished = true;
mdatEndTimeData.push({
timestamp: _getCurrentTimestamp(),
bytes: data.length
});
}
// Announce progress but don't track traces. Throughput measures are quite unstable
// when they are based in small amount of data
commonMediaRequest.customData.onprogress({
data: data.buffer,
lengthComputable: false,
noTrace: true
});
endPositionOfLastProcessedBoxInReceivedData = 0;
}
/**
* Make the data that we received available for playback
* If we are going to pass full buffer, avoid copying it and pass
* complete buffer. Otherwise, clone the part of the buffer that is completed
* and adjust remaining buffer. A clone is needed because ArrayBuffer of a typed-array
* keeps a reference to the original data
* @param endPositionOfLastTargetBox
* @returns {Uint8Array}
* @private
*/
function _getDataForMediaSourceBufferAndAdjustReceivedData(endPositionOfLastTargetBox) {
let data;
if (endPositionOfLastTargetBox === receivedData.length) {
data = receivedData;
receivedData = new Uint8Array();
} else {
data = new Uint8Array(receivedData.subarray(0, endPositionOfLastTargetBox));
receivedData = receivedData.subarray(endPositionOfLastTargetBox);
}
return data
}
function _handleNoCompletedTopIsoBox(boxesInfo) {
endPositionOfLastProcessedBoxInReceivedData = boxesInfo.startOffsetOfLastCompletedBox + boxesInfo.sizeOfLastCompletedBox;
// Call progress, so it generates traces that will be later used to know when the first byte
// were received
if (!signaledFirstByte) {
commonMediaRequest.customData.onprogress({
lengthComputable: false,
noTrace: true
});
signaledFirstByte = true;
}
}
_readResponseBody(commonMediaRequest, commonMediaResponse, _processResult);
}
/**
* Reads the response of the request. For details refer to https://developer.mozilla.org/en-US/docs/Web/API/ReadableStreamDefaultReader/read
* @param {CommonMediaRequest} commonMediaRequest
* @param {CommonMediaResponse} commonMediaResponse
* @param processResult
* @private
*/
function _readResponseBody(commonMediaRequest, commonMediaResponse, processResult) {
commonMediaRequest.customData.reader.read()
.then(processResult)
.catch(function () {
_handleFetchError(commonMediaRequest);
});
}
function _handleFetchError(commonMediaRequest) {
if (commonMediaRequest.customData.onloadend) {
commonMediaRequest.customData.onloadend();
}
}
function _updateCommonMediaResponseInstance(commonMediaResponse, fetchResponse) {
commonMediaResponse.status = fetchResponse.status;
commonMediaResponse.statusText = fetchResponse.statusText;
commonMediaResponse.url = fetchResponse.url;
const responseHeaders = {};
for (const key of fetchResponse.headers.keys()) {
responseHeaders[key] = fetchResponse.headers.get(key);
}
commonMediaResponse.headers = responseHeaders;
}
function _getHeaders(commonMediaRequest) {
const headers = new Headers();
if (commonMediaRequest.headers) {
for (let header in commonMediaRequest.headers) {
let value = commonMediaRequest.headers[header];
if (value) {
headers.append(header, value);
}
}
}
return headers
}
function _setupAbortMechanism(commonMediaRequest) {
let abortController;
if (typeof window.AbortController === 'function') {
abortController = new AbortController();
commonMediaRequest.customData.abortController = abortController;
abortController.signal.onabort = commonMediaRequest.customData.onabort;
}
commonMediaRequest.customData.abort = abort.bind(commonMediaRequest);
return abortController
}
function _getFetchResourceRequestObject(commonMediaRequest, headers, abortController) {
const fetchResourceRequestObject = new Request(commonMediaRequest.url, {
method: commonMediaRequest.method,
headers: headers,
credentials: commonMediaRequest.credentials,
signal: abortController ? abortController.signal : undefined
});
return fetchResourceRequestObject
}
function _getCurrentTimestamp() {
if (typeof performance !== 'undefined' && typeof performance.now === 'function') {
return performance.now();
} else {
return Date.now();
}
}
/**
* Creates a new Uint8 array and adds the existing data as well as new data
* @param receivedData
* @param data
* @returns {Uint8Array|*}
* @private
*/
function _concatTypedArray(receivedData, data) {
if (receivedData.length === 0) {
return data;
}
const result = new Uint8Array(receivedData.length + data.length);
result.set(receivedData);
// set(typedarray, targetOffset)
result.set(data, receivedData.length);
return result;
}
/**
* Use the AbortController to abort a request
* @param request
*/
function abort() {
// this = httpRequest (CommonMediaRequest)
if (this.customData.abortController) {
// For firefox and edge
this.customData.abortController.abort();
} else if (this.customData.reader) {
// For Chrome
try {
this.customData.reader.cancel();
this.onabort();
} catch (e) {
// throw exceptions (TypeError) when reader was previously closed,
// for example, because a network issue
}
}
}
function reset() {
}
/**
* Default throughput calculation
* @param downloadedData
* @param bytesReceived
* @returns {number|null}
* @private
*/
function calculateDownloadedTime(downloadedData, bytesReceived) {
try {
downloadedData = downloadedData.filter(data => data.bytes > ((bytesReceived / 4) / downloadedData.length));
if (downloadedData.length > 1) {
let time = 0;
const avgTimeDistance = (downloadedData[downloadedData.length - 1].timestamp - downloadedData[0].timestamp) / downloadedData.length;
downloadedData.forEach((data, index) => {
// To be counted the data has to be over a threshold
const next = downloadedData[index + 1];
if (next) {
const distance = next.timestamp - data.timestamp;
time += distance < avgTimeDistance ? distance : 0;
}
});
return time;
}
return null;
} catch (e) {
return null;
}
}
function _calculateThroughputByMoofMdatTimes(moofStartTimeData, mdatEndTimeData) {
try {
let filteredMoofStartTimeData,
filteredMdatEndTimeData;
// Filter the last chunks in a segment in both arrays [StartTimeData and EndTimeData]
filteredMoofStartTimeData = moofStartTimeData.slice(0, -1);
filteredMdatEndTimeData = mdatEndTimeData.slice(0, -1);
if (filteredMoofStartTimeData.length !== filteredMdatEndTimeData.length) {
logger.warn(`[FetchLoader] Moof and Mdat data arrays have different lengths. Moof: ${filteredMoofStartTimeData.length}, Mdat: ${filteredMdatEndTimeData.length}`);
}
if (filteredMoofStartTimeData.length <= 1) {
return null;
}
let chunkThroughputValues = [];
let shortDurationBytesReceived = 0;
let shortDurationStartTime = 0;
for (let i = 0; i < filteredMoofStartTimeData.length; i++) {
if (filteredMoofStartTimeData[i] && filteredMdatEndTimeData[i]) {
let chunkDownloadTime = filteredMdatEndTimeData[i].timestamp - filteredMoofStartTimeData[i].timestamp;
if (chunkDownloadTime > 1) {
const throughput = _getThroughputInBitPerMs(filteredMdatEndTimeData[i].bytes, chunkDownloadTime);
chunkThroughputValues.push(throughput);
shortDurationStartTime = 0;
} else {
if (shortDurationStartTime === 0) {
shortDurationStartTime = filteredMoofStartTimeData[i].timestamp;
shortDurationBytesReceived = 0;
}
let cumulatedChunkDownloadTime = filteredMdatEndTimeData[i].timestamp - shortDurationStartTime;
if (cumulatedChunkDownloadTime > 1) {
shortDurationBytesReceived += filteredMdatEndTimeData[i].bytes;
const throughput = _getThroughputInBitPerMs(shortDurationBytesReceived, cumulatedChunkDownloadTime);
chunkThroughputValues.push(throughput);
shortDurationStartTime = 0;
} else {
// continue cumulating short duration data
shortDurationBytesReceived += filteredMdatEndTimeData[i].bytes;
}
}
}
}
if (chunkThroughputValues.length > 0) {
const sumOfChunkThroughputValues = chunkThroughputValues.reduce((a, b) => a + b, 0);
return sumOfChunkThroughputValues / chunkThroughputValues.length;
}
return null;
} catch (e) {
return null;
}
}
function _getThroughputInBitPerMs(bytes, timeInMs) {
return (8 * bytes) / timeInMs
}
setup();
instance = {
abort,
calculateDownloadedTime,
load,
reset,
setConfig,
};
return instance;
}
FetchLoader.__dashjs_factory_name = 'FetchLoader';
const factory = FactoryMaker.getClassFactory(FetchLoader);
export default factory;
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