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Avoid ewma sampling from failing on 0 duration segments. #583

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Nov 16, 2016
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Avoid ewma sampling from failing on 0 duration segments. #583

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b818ed7
Avoid ewma sampling from failing on 0 duration segments.
Nov 10, 2016
9387fef
Fix linting errors
Nov 16, 2016
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8 changes: 6 additions & 2 deletions lib/abr/ewma.js
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Original file line number Diff line number Diff line change
Expand Up @@ -54,8 +54,12 @@ shaka.abr.Ewma = function(halfLife) {
*/
shaka.abr.Ewma.prototype.sample = function(weight, value) {
var adjAlpha = Math.pow(this.alpha_, weight);
this.estimate_ = value * (1 - adjAlpha) + adjAlpha * this.estimate_;
this.totalWeight_ += weight;
var newEstimate = value * (1 - adjAlpha) + adjAlpha * this.estimate_;

if (!isNaN(newEstimate)) {
this.estimate_ = newEstimate;
this.totalWeight_ += weight;
}
};


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23 changes: 23 additions & 0 deletions test/abr/simple_abr_manager_unit.js
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Expand Up @@ -182,6 +182,29 @@ describe('SimpleAbrManager', function() {
});
});

it('can handle 0 duration segments', function() {
var audioBandwidth = 5e5;
var videoBandwidth = 2e6;
var bytesPerSecond =
sufficientBWMultiplier * (audioBandwidth + videoBandwidth) / 8.0;

abrManager.chooseStreams(streamSetsByType);

// 0 duration segment shouldn't cause us to get stuck on the lowest variant
abrManager.segmentDownloaded(1000, 1000, bytesPerSecond);
abrManager.segmentDownloaded(2000, 3000, bytesPerSecond);

abrManager.enable();

abrManager.segmentDownloaded(4000, 5000, bytesPerSecond);

expect(switchCallback).toHaveBeenCalled();
expect(switchCallback.calls.argsFor(0)[0]).toEqual({
'audio': jasmine.objectContaining({bandwidth: audioBandwidth}),
'video': jasmine.objectContaining({bandwidth: videoBandwidth})
});
});

it('picks lowest audio Stream when there is insufficient bandwidth',
function() {
// The lowest audio track will only be chosen if needed to fit the
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