/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.media.MetaSegmentIndex');
goog.provide('shaka.media.SegmentIndex');
goog.provide('shaka.media.SegmentIterator');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.media.SegmentReference');
goog.require('shaka.util.IReleasable');
goog.require('shaka.util.Timer');
/**
* SegmentIndex.
*
* @implements {shaka.util.IReleasable}
* @implements {Iterable.<!shaka.media.SegmentReference>}
* @export
*/
shaka.media.SegmentIndex = class {
/**
* @param {!Array.<!shaka.media.SegmentReference>} references The list of
* SegmentReferences, which must be sorted first by their start times
* (ascending) and second by their end times (ascending).
*/
constructor(references) {
if (goog.DEBUG) {
shaka.media.SegmentIndex.assertCorrectReferences_(references);
}
/** @protected {!Array.<!shaka.media.SegmentReference>} */
this.references = references;
/** @private {shaka.util.Timer} */
this.timer_ = null;
/**
* The number of references that have been removed from the front of the
* array. Used to create stable positions in the find/get APIs.
*
* @protected {number}
*/
this.numEvicted_ = 0;
/** @private {boolean} */
this.immutable_ = false;
}
/**
* Get immutability
*
* @return {boolean}
*/
getIsImmutable() {
return this.immutable_;
}
/**
* Get number of references
* @protected
* @return {number}
*/
getNumReferences() {
return this.references.length;
}
/**
* @override
* @export
*/
release() {
if (this.immutable_) {
return;
}
this.references = [];
if (this.timer_) {
this.timer_.stop();
}
this.timer_ = null;
}
/**
* Marks the index as immutable. Segments cannot be added or removed after
* this point. This doesn't affect the references themselves. This also
* makes the destroy/release methods do nothing.
*
* This is mainly for testing.
*
* @export
*/
markImmutable() {
this.immutable_ = true;
}
/**
* Iterates over all top-level segment references in this segment index.
* @param {function(!shaka.media.SegmentReference)} fn
*/
forEachTopLevelReference(fn) {
for (const reference of this.references) {
fn(reference);
}
}
/**
* Return the earliest reference, or null if empty.
* @return {shaka.media.SegmentReference}
*/
earliestReference() {
return this.references[0] || null;
}
/**
* Drop the first N references.
* Used in early HLS synchronization, and does not count as eviction.
* @param {number} n
*/
dropFirstReferences(n) {
this.references.splice(0, n);
}
/**
* Finds the position of the segment for the given time, in seconds, relative
* to the start of the presentation. Returns the position of the segment
* with the largest end time if more than one segment is known for the given
* time.
*
* @param {number} time
* @return {?number} The position of the segment, or null if the position of
* the segment could not be determined.
* @export
*/
find(time) {
// For live streams, searching from the end is faster. For VOD, it balances
// out either way. In both cases, references.length is small enough that
// the difference isn't huge.
const lastReferenceIndex = this.references.length - 1;
for (let i = lastReferenceIndex; i >= 0; --i) {
const r = this.references[i];
const start = r.startTime;
// A rounding error can cause /time/ to equal e.endTime or fall in between
// the references by a fraction of a second. To account for this, we use
// the start of the next segment as /end/, unless this is the last
// reference, in which case we use its end time as /end/.
const end = i < lastReferenceIndex ?
this.references[i + 1].startTime : r.endTime;
// Note that a segment ends immediately before the end time.
if ((time >= start) && (time < end)) {
return i + this.numEvicted_;
}
}
if (this.references.length && time < this.references[0].startTime) {
return this.numEvicted_;
}
return null;
}
/**
* Gets the SegmentReference for the segment at the given position.
*
* @param {number} position The position of the segment as returned by find().
* @return {shaka.media.SegmentReference} The SegmentReference, or null if
* no such SegmentReference exists.
* @export
*/
get(position) {
if (this.references.length == 0) {
return null;
}
const index = position - this.numEvicted_;
if (index < 0 || index >= this.references.length) {
return null;
}
return this.references[index];
}
/**
* Offset all segment references by a fixed amount.
*
* @param {number} offset The amount to add to each segment's start and end
* times.
* @export
*/
offset(offset) {
if (!this.immutable_) {
for (const ref of this.references) {
ref.offset(offset);
}
}
}
/**
* Merges the given SegmentReferences. Supports extending the original
* references only. Will replace old references with equivalent new ones, and
* keep any unique old ones.
*
* Used, for example, by the DASH and HLS parser, where manifests may not list
* all available references, so we must keep available references in memory to
* fill the availability window.
*
* @param {!Array.<!shaka.media.SegmentReference>} references The list of
* SegmentReferences, which must be sorted first by their start times
* (ascending) and second by their end times (ascending).
*/
merge(references) {
if (goog.DEBUG) {
shaka.media.SegmentIndex.assertCorrectReferences_(references);
}
if (this.immutable_) {
return;
}
if (!references.length) {
return;
}
// Partial segments are used for live edge, and should be removed when they
// get older. Remove the old SegmentReferences after the first new
// reference's start time.
// Use times rounded to the millisecond for filtering purposes, so that
// tiny rounding errors will not result in duplicate segments in the index.
const firstStartTime = Math.round(references[0].startTime * 1000) / 1000;
this.references = this.references.filter((r) => {
return (Math.round(r.startTime * 1000) / 1000) < firstStartTime;
});
this.references.push(...references);
if (goog.DEBUG) {
shaka.media.SegmentIndex.assertCorrectReferences_(this.references);
}
}
/**
* Merges the given SegmentReferences and evicts the ones that end before the
* given time. Supports extending the original references only.
* Will not replace old references or interleave new ones.
* Used, for example, by the DASH and HLS parser, where manifests may not list
* all available references, so we must keep available references in memory to
* fill the availability window.
*
* @param {!Array.<!shaka.media.SegmentReference>} references The list of
* SegmentReferences, which must be sorted first by their start times
* (ascending) and second by their end times (ascending).
* @param {number} windowStart The start of the availability window to filter
* out the references that are no longer available.
* @export
*/
mergeAndEvict(references, windowStart) {
// Filter out the references that are no longer available to avoid
// repeatedly evicting them and messing up eviction count.
references = references.filter((r) => {
return r.endTime > windowStart &&
(this.references.length == 0 ||
r.endTime > this.references[0].startTime);
});
const oldFirstRef = this.references[0];
this.merge(references);
const newFirstRef = this.references[0];
if (oldFirstRef) {
// We don't compare the actual ref, since the object could legitimately be
// replaced with an equivalent. Even the URIs could change due to
// load-balancing actions taken by the server. However, if the time
// changes, its not an equivalent reference.
goog.asserts.assert(oldFirstRef.startTime == newFirstRef.startTime,
'SegmentIndex.merge should not change the first reference time!');
}
this.evict(windowStart);
}
/**
* Removes all SegmentReferences that end before the given time.
*
* @param {number} time The time in seconds.
* @export
*/
evict(time) {
if (this.immutable_) {
return;
}
const oldSize = this.references.length;
this.references = this.references.filter((ref) => ref.endTime > time);
const newSize = this.references.length;
const diff = oldSize - newSize;
// Tracking the number of evicted refs will keep their "positions" stable
// for the caller.
this.numEvicted_ += diff;
}
/**
* Drops references that start after windowEnd, or end before windowStart,
* and contracts the last reference so that it ends at windowEnd.
*
* Do not call on the last period of a live presentation (unknown duration).
* It is okay to call on the other periods of a live presentation, where the
* duration is known and another period has been added.
*
* @param {number} windowStart
* @param {?number} windowEnd
* @param {boolean=} isNew Whether this is a new SegmentIndex and we shouldn't
* update the number of evicted elements.
* @export
*/
fit(windowStart, windowEnd, isNew = false) {
goog.asserts.assert(windowEnd != null,
'Content duration must be known for static content!');
goog.asserts.assert(windowEnd != Infinity,
'Content duration must be finite for static content!');
if (this.immutable_) {
return;
}
// Trim out references we will never use.
while (this.references.length) {
const lastReference = this.references[this.references.length - 1];
if (lastReference.startTime >= windowEnd) {
this.references.pop();
} else {
break;
}
}
while (this.references.length) {
const firstReference = this.references[0];
if (firstReference.endTime <= windowStart) {
this.references.shift();
if (!isNew) {
this.numEvicted_++;
}
} else {
break;
}
}
if (this.references.length == 0) {
return;
}
// Adjust the last SegmentReference.
const lastReference = this.references[this.references.length - 1];
const newReference = new shaka.media.SegmentReference(
lastReference.startTime,
/* endTime= */ windowEnd,
lastReference.getUrisInner,
lastReference.startByte,
lastReference.endByte,
lastReference.initSegmentReference,
lastReference.timestampOffset,
lastReference.appendWindowStart,
lastReference.appendWindowEnd,
lastReference.partialReferences,
lastReference.tilesLayout,
lastReference.tileDuration,
lastReference.syncTime,
lastReference.status,
lastReference.aes128Key,
);
newReference.mimeType = lastReference.mimeType;
newReference.codecs = lastReference.codecs;
newReference.discontinuitySequence = lastReference.discontinuitySequence;
this.references[this.references.length - 1] = newReference;
}
/**
* Updates the references every so often. Stops when the references list
* returned by the callback is null.
*
* @param {number} interval The interval in seconds.
* @param {function():Array.<shaka.media.SegmentReference>} updateCallback
* @export
*/
updateEvery(interval, updateCallback) {
goog.asserts.assert(!this.timer_, 'SegmentIndex timer already started!');
if (this.immutable_) {
return;
}
if (this.timer_) {
this.timer_.stop();
}
this.timer_ = new shaka.util.Timer(() => {
const references = updateCallback();
if (references) {
this.references.push(...references);
} else {
this.timer_.stop();
this.timer_ = null;
}
});
this.timer_.tickEvery(interval);
}
/** @return {!shaka.media.SegmentIterator} */
[Symbol.iterator]() {
const iter = this.getIteratorForTime(0);
goog.asserts.assert(iter != null, 'Iterator for 0 should never be null!');
return iter;
}
/**
* Returns a new iterator that initially points to the segment that contains
* the given time, or the nearest independent segment before it.
*
* Like the normal iterator, next() must be called first to get to the first
* element. Returns null if we do not find a segment at the
* requested time.
*
* The first segment returned by the iterator _MUST_ be an independent
* segment. Assumes that only partial references can be dependent, based on
* RFC 8216 rev 13, section 8.1: "Each (non-Partial) Media Segment in a Media
* Playlist will contain at least one independent frame."
*
* @param {number} time
* @return {?shaka.media.SegmentIterator}
* @export
*/
getIteratorForTime(time) {
let index = this.find(time);
if (index == null) {
return null;
} else {
index--;
}
// +1 so we can get the element we'll eventually point to so we can see if
// we need to use a partial segment index.
const ref = this.get(index + 1);
let partialSegmentIndex = -1;
if (ref && ref.hasPartialSegments()) {
// Look for a partial SegmentReference.
for (let i = ref.partialReferences.length - 1; i >= 0; --i) {
let r = ref.partialReferences[i];
// Note that a segment ends immediately before the end time.
if ((time >= r.startTime) && (time < r.endTime)) {
// Find an independent partial segment by moving backwards.
while (i && !r.isIndependent()) {
i--;
r = ref.partialReferences[i];
}
if (!r.isIndependent()) {
shaka.log.alwaysError('No independent partial segment found!');
return null;
}
// Call to next() should move the partial segment, not the full
// segment.
index++;
partialSegmentIndex = i - 1;
break;
}
}
}
return new shaka.media.SegmentIterator(this, index, partialSegmentIndex);
}
/**
* @return {boolean}
*/
isEmpty() {
return this.getNumReferences() == 0;
}
/**
* Create a SegmentIndex for a single segment of the given start time and
* duration at the given URIs.
*
* @param {number} startTime
* @param {number} duration
* @param {!Array.<string>} uris
* @return {!shaka.media.SegmentIndex}
* @export
*/
static forSingleSegment(startTime, duration, uris) {
const reference = new shaka.media.SegmentReference(
/* startTime= */ startTime,
/* endTime= */ startTime + duration,
/* getUris= */ () => uris,
/* startByte= */ 0,
/* endByte= */ null,
/* initSegmentReference= */ null,
/* presentationTimeOffset= */ startTime,
/* appendWindowStart= */ startTime,
/* appendWindowEnd= */ startTime + duration);
return new shaka.media.SegmentIndex([reference]);
}
};
if (goog.DEBUG) {
/**
* Asserts that the given SegmentReferences are sorted.
*
* @param {!Array.<shaka.media.SegmentReference>} references
* @private
*/
shaka.media.SegmentIndex.assertCorrectReferences_ = (references) => {
goog.asserts.assert(references.every((r2, i) => {
if (i == 0) {
return true;
}
const r1 = references[i - 1];
if (r1.startTime < r2.startTime) {
return true;
} else if (r1.startTime > r2.startTime) {
return false;
} else {
if (r1.endTime <= r2.endTime) {
return true;
} else {
return false;
}
}
}), 'SegmentReferences are incorrect');
};
}
/**
* An iterator over a SegmentIndex's references.
*
* @implements {Iterator.<shaka.media.SegmentReference>}
* @export
*/
shaka.media.SegmentIterator = class {
/**
* @param {shaka.media.SegmentIndex} segmentIndex
* @param {number} index
* @param {number} partialSegmentIndex
*/
constructor(segmentIndex, index, partialSegmentIndex) {
/** @private {shaka.media.SegmentIndex} */
this.segmentIndex_ = segmentIndex;
/** @private {number} */
this.currentPosition_ = index;
/** @private {number} */
this.currentPartialPosition_ = partialSegmentIndex;
}
/**
* @return {number}
* @export
*/
currentPosition() {
return this.currentPosition_;
}
/**
* @return {shaka.media.SegmentReference}
* @export
*/
current() {
let ref = this.segmentIndex_.get(this.currentPosition_);
// When we advance past the end of partial references in next(), then add
// new references in merge(), the pointers may not make sense any more.
// This adjusts the invalid pointer values to point to the next newly added
// segment or partial segment.
if (ref && ref.hasPartialSegments() && ref.hasAllPartialSegments() &&
this.currentPartialPosition_ >= ref.partialReferences.length) {
this.currentPosition_++;
this.currentPartialPosition_ = 0;
ref = this.segmentIndex_.get(this.currentPosition_);
}
// If the regular segment contains partial segments, get the current
// partial SegmentReference.
if (ref && ref.hasPartialSegments()) {
const partial = ref.partialReferences[this.currentPartialPosition_];
return partial;
}
return ref;
}
/**
* @override
* @export
*/
next() {
const ref = this.segmentIndex_.get(this.currentPosition_);
if (ref && ref.hasPartialSegments()) {
// If the regular segment contains partial segments, move to the next
// partial SegmentReference.
this.currentPartialPosition_++;
// If the current regular segment has been published completely, and
// we've reached the end of its partial segments list, move to the next
// regular segment.
// If the Partial Segments list is still on the fly, do not move to
// the next regular segment.
if (ref.hasAllPartialSegments() &&
this.currentPartialPosition_ == ref.partialReferences.length) {
this.currentPosition_++;
this.currentPartialPosition_ = 0;
}
} else {
// If the regular segment doesn't contain partial segments, move to the
// next regular segment.
this.currentPosition_++;
this.currentPartialPosition_ = 0;
}
const res = this.current();
return {
'value': res,
'done': !res,
};
}
};
/**
* A meta-SegmentIndex composed of multiple other SegmentIndexes.
* Used in constructing multi-Period Streams for DASH.
*
* @extends shaka.media.SegmentIndex
* @implements {shaka.util.IReleasable}
* @implements {Iterable.<!shaka.media.SegmentReference>}
* @export
*/
shaka.media.MetaSegmentIndex = class extends shaka.media.SegmentIndex {
/** */
constructor() {
super([]);
/** @private {!Array.<!shaka.media.SegmentIndex>} */
this.indexes_ = [];
}
/**
* Append a SegmentIndex to this MetaSegmentIndex. This effectively stitches
* the underlying Stream onto the end of the multi-Period Stream represented
* by this MetaSegmentIndex.
*
* @param {!shaka.media.SegmentIndex} segmentIndex
*/
appendSegmentIndex(segmentIndex) {
goog.asserts.assert(
this.indexes_.length == 0 || segmentIndex.numEvicted_ == 0,
'Should not append a new segment index with already-evicted segments');
this.indexes_.push(segmentIndex);
}
/**
* Create a clone of this MetaSegmentIndex containing all the same indexes.
*
* @return {!shaka.media.MetaSegmentIndex}
*/
clone() {
const clone = new shaka.media.MetaSegmentIndex();
// Be careful to clone the Array. We don't want to share the reference with
// our clone and affect each other accidentally.
clone.indexes_ = this.indexes_.slice();
return clone;
}
/**
* @override
* @export
*/
release() {
for (const index of this.indexes_) {
index.release();
}
this.indexes_ = [];
}
/**
* @override
* @export
*/
forEachTopLevelReference(fn) {
for (const index of this.indexes_) {
index.forEachTopLevelReference(fn);
}
}
/**
* @override
* @export
*/
find(time) {
let numPassedInEarlierIndexes = 0;
for (const index of this.indexes_) {
const position = index.find(time);
if (position != null) {
return position + numPassedInEarlierIndexes;
}
numPassedInEarlierIndexes += index.numEvicted_ +
index.getNumReferences();
}
return null;
}
/**
* @override
* @export
*/
get(position) {
let numPassedInEarlierIndexes = 0;
let sawSegments = false;
for (const index of this.indexes_) {
goog.asserts.assert(
!sawSegments || index.numEvicted_ == 0,
'Should not see evicted segments after available segments');
const reference = index.get(position - numPassedInEarlierIndexes);
if (reference) {
return reference;
}
const num = index.getNumReferences();
numPassedInEarlierIndexes += index.numEvicted_ + num;
sawSegments = sawSegments || num != 0;
}
return null;
}
/**
* @override
* @export
*/
offset(offset) {
// offset() is only used by HLS, and MetaSegmentIndex is only used for DASH.
goog.asserts.assert(
false, 'offset() should not be used in MetaSegmentIndex!');
}
/**
* @override
* @export
*/
merge(references) {
// merge() is only used internally by the DASH and HLS parser on
// SegmentIndexes, but never on MetaSegmentIndex.
goog.asserts.assert(
false, 'merge() should not be used in MetaSegmentIndex!');
}
/**
* @override
* @export
*/
evict(time) {
// evict() is only used internally by the DASH and HLS parser on
// SegmentIndexes, but never on MetaSegmentIndex.
goog.asserts.assert(
false, 'evict() should not be used in MetaSegmentIndex!');
}
/**
* @override
* @export
*/
mergeAndEvict(references, windowStart) {
// mergeAndEvict() is only used internally by the DASH and HLS parser on
// SegmentIndexes, but never on MetaSegmentIndex.
goog.asserts.assert(
false, 'mergeAndEvict() should not be used in MetaSegmentIndex!');
}
/**
* @override
* @export
*/
fit(windowStart, windowEnd) {
// fit() is only used internally by manifest parsers on SegmentIndexes, but
// never on MetaSegmentIndex.
goog.asserts.assert(false, 'fit() should not be used in MetaSegmentIndex!');
}
/**
* @override
* @export
*/
updateEvery(interval, updateCallback) {
// updateEvery() is only used internally by the DASH parser on
// SegmentIndexes, but never on MetaSegmentIndex.
goog.asserts.assert(
false, 'updateEvery() should not be used in MetaSegmentIndex!');
}
};