mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-16 16:16:40 +03:00
Álvaro Velad Galván
66 lines
2.0 KiB
JavaScript
66 lines
2.0 KiB
JavaScript
/*! @license
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* Shaka Player
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* Copyright 2026 Google LLC
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* SPDX-License-Identifier: Apache-2.0
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*/
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goog.provide('shaka.msf.MSFPresentationTimeline');
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goog.require('shaka.media.PresentationTimeline');
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/**
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* A PresentationTimeline variant for MoQ/MSF live streams.
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*
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* Unlike the standard timeline, the live edge is derived directly from the
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* latest known segment end time rather than from wall-clock arithmetic.
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* This is correct for MoQ because:
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* 1. The server delivers from the live edge; segment timestamps ARE the
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* truth.
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* 2. There is no encoder/clock drift to compensate for.
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*
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* @extends {shaka.media.PresentationTimeline}
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* @export
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* @final
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*/
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// eslint-disable-next-line @stylistic/max-len
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shaka.msf.MSFPresentationTimeline = class extends shaka.media.PresentationTimeline {
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constructor() {
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// presentationStartTime=null avoids wall-clock live edge in base class.
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// delay=0 because MoQ targets minimum latency.
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// maxSegmentDuration=0 because the segments can be very small.
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super(/* presentationStartTime= */ null, /* delay= */ 0,
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/* autoCorrectDrift= */ false, /* maxSegmentDuration= */ 0);
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}
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/**
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* For MoQ live: the availability end IS the latest segment end time.
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* No wall-clock arithmetic needed.
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* @override
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* @export
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*/
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getSegmentAvailabilityEnd() {
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if (!this.isDynamic()) {
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return super.getSegmentAvailabilityEnd();
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}
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const maxSegmentEndTime = this.getMaxSegmentEndTime();
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return maxSegmentEndTime != null ? maxSegmentEndTime : 0;
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}
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/**
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* Zero seek range: the availability window is exactly one segment wide.
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* Users cannot seek back on Live.
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* @override
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* @export
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*/
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getSegmentAvailabilityStart() {
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if (!this.isDynamic()) {
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return super.getSegmentAvailabilityStart();
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}
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// Keep one segment of headroom so the player never falls out of range
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// due to the 250ms onPollWindow_ tick.
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return Math.max(0,
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this.getSegmentAvailabilityEnd() - this.getMaxSegmentDuration());
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}
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};
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