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rateBasedSwitching.js
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rateBasedSwitching.js
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/****************************************************************************
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* For more information, please refer to <https://unlicense.org>
*
****************************************************************************/
const bitmovin = window.bitmovin;
var RateBasedSwitching = function (player, bufferSize, segmentLength) {
var downloadRates = [];
var maxBufferLevel = null;
function onDownloadFinished(event) {
if (event.downloadType === 'media/video' && event.url.indexOf('video') > -1) {
downloadRates.unshift((event.size * 8) / event.downloadTime);
while (downloadRates.length > bufferSize) {
downloadRates.pop();
}
}
}
function resetBuffer() {
downloadRates = [];
}
function getMeanBitrate() {
var mean = 0;
var count = 0;
var depth = Math.min(Math.max(1, parseInt(Math.min(player.getVideoBufferLength() / (maxBufferLevel - segmentLength), 1) * bufferSize)), downloadRates.length);
for (var idx = 0; idx < depth; idx++) {
var currentValue = downloadRates[idx] * (1 - (idx * (1 / bufferSize)));
if (currentValue < 0) break;
mean += currentValue;
count++;
}
return count > 0 ? (mean / count) : 0;
}
function onVideoAdaptation() {
var availableVideoQualities = player.getAvailableVideoQualities();
var maxVideoRepresentation = {bitrate: 0};
var minVideoRepresentation = {bitrate: Infinity};
var meanBitrate = getMeanBitrate();
for (var idx = 0; idx < availableVideoQualities.length; idx++) {
if (maxVideoRepresentation.bitrate < availableVideoQualities[idx].bitrate && availableVideoQualities[idx].bitrate < meanBitrate) {
maxVideoRepresentation = availableVideoQualities[idx];
}
if (availableVideoQualities[idx].bitrate < minVideoRepresentation.bitrate) {
minVideoRepresentation = availableVideoQualities[idx];
}
}
if (maxVideoRepresentation.id) {
return maxVideoRepresentation.id;
} else {
return minVideoRepresentation.id;
}
}
(function () {
if (!player) {
return;
}
if (player.getConfig().hasOwnProperty('tweaks') && player.getConfig().tweaks.hasOwnProperty('max_buffer_level')) {
maxBufferLevel = player.getConfig().tweaks.max_buffer_level;
} else {
maxBufferLevel = 20;
}
var init = function () {
player.on(bitmovin.player.PlayerEvent.DownloadFinished, onDownloadFinished);
player.on(bitmovin.player.PlayerEvent.StallStarted, resetBuffer);
player.on(bitmovin.player.PlayerEvent.VideoAdaptation, onVideoAdaptation);
};
if (player.getSource()) {
init();
} else {
player.on(bitmovin.player.PlayerEvent.SourceLoaded, init);
}
})();
};