shaka-player
Version:
DASH/EME video player library
270 lines (239 loc) • 8.49 kB
JavaScript
/**
* @license
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
goog.provide('shaka.util.ManifestFilter');
goog.require('goog.asserts');
/**
* This utility class contains all the functions used to filter manifests
* before playback and before storage.
*/
shaka.util.ManifestFilter = class {
/**
* Filter the variants in |manifest| to only include the variants that meet
* the given restrictions.
*
* @param {shaka.extern.Manifest} manifest
* @param {shaka.extern.Restrictions} restrictions
* @param {{width: number, height:number}} maxHwResolution
*/
static filterByRestrictions(manifest, restrictions, maxHwResolution) {
for (const period of manifest.periods) {
period.variants = period.variants.filter((variant) => {
return shaka.util.StreamUtils.meetsRestrictions(
variant, restrictions, maxHwResolution);
});
}
}
/**
* Filter the variants in the |manifest| to only include those that are
* supported by media source.
*
* @param {shaka.extern.Manifest} manifest
*/
static filterByMediaSourceSupport(manifest) {
const MediaSourceEngine = shaka.media.MediaSourceEngine;
for (const period of manifest.periods) {
period.variants = period.variants.filter((variant) => {
let supported = true;
if (variant.audio) {
supported =
supported && MediaSourceEngine.isStreamSupported(variant.audio);
}
if (variant.video) {
supported =
supported && MediaSourceEngine.isStreamSupported(variant.video);
}
return supported;
});
}
}
/**
* Filter the variants in |manifest| to only include those that are supported
* by |drm|.
*
* @param {shaka.extern.Manifest} manifest
* @param {!shaka.media.DrmEngine} drmEngine
*/
static filterByDrmSupport(manifest, drmEngine) {
for (const period of manifest.periods) {
period.variants = period.variants.filter((variant) => {
return drmEngine.supportsVariant(variant);
});
}
}
/**
* Filter the variants in |manifest| to only include those that use codecs
* that will be supported in each variant. This ensures playback from the
* first period to the last period by "jumping between" compatible variants.
*
* @param {shaka.extern.Manifest} manifest
*/
static filterByCommonCodecs(manifest) {
goog.asserts.assert(manifest.periods.length > 0,
'There should be at least be one period');
const ManifestFilter = shaka.util.ManifestFilter;
// Create a set of summaries that occur in each period.
/** @type {!shaka.util.ManifestFilter.VariantCodecSummarySet} */
const common = new shaka.util.ManifestFilter.VariantCodecSummarySet();
manifest.periods.forEach((period, index) => {
/** @type {!shaka.util.ManifestFilter.VariantCodecSummarySet} */
const next = ManifestFilter.VariantCodecSummarySet.fromVariants(
period.variants);
if (index == 0) {
common.includeAll(next);
} else {
common.onlyKeep(next);
}
});
// Filter the variants in the period by whether they match a summary that
// occurs in every period.
for (const period of manifest.periods) {
period.variants = period.variants.filter((variant) => {
const summary = new ManifestFilter.VariantCodecSummary(variant);
return common.contains(summary);
});
}
}
/**
* Go through each period and apply the filter to the set of variants.
* |filter| will only be given the set of variants in the current period that
* are compatible with at least one variant in the previous period.
*
* @param {shaka.extern.Manifest} manifest
* @param {function(shaka.extern.Period):!Promise} filter
* @return {!Promise}
*/
static async rollingFilter(manifest, filter) {
// Store a reference to the variants so that the next period can easily
// reference them too.
/** @type {shaka.util.ManifestFilter.VariantCodecSummarySet} */
let previous = null;
for (const period of manifest.periods) {
// Remove all variants that don't have a compatible variant in the
// previous period. If we were to only use the first variant, we would
// risk a variant being removed from a later period that would break that
// path across all periods.
if (previous) {
period.variants = period.variants.filter((variant) => {
const summary =
new shaka.util.ManifestFilter.VariantCodecSummary(variant);
return previous.contains(summary);
});
}
// eslint-disable-next-line no-await-in-loop
await filter(period);
// Use the results of filtering this period as the "previous" for the
// next period.
previous = shaka.util.ManifestFilter.VariantCodecSummarySet.fromVariants(
period.variants);
}
}
};
/**
* The variant codec summary is a summary of the codec information for a given
* codec. This can be used to test the compatibility between variants by
* checking that their summaries contain the same information.
*
* @final
*/
shaka.util.ManifestFilter.VariantCodecSummary = class {
/**
* @param {shaka.extern.Variant} variant
*/
constructor(variant) {
// We summarize a variant based on the basic mime type and the basic
// codec because they must match for two variants to be compatible. For
// example, we can't adapt between WebM and MP4, nor can we adapt between
// mp4a.* to ec-3.
const audio = variant.audio;
const video = variant.video;
/** @private {?string} */
this.audioMime_ = audio ? audio.mimeType : null;
/** @private {?string} */
this.audioCodec_ = audio ? audio.codecs.split('.')[0] : null;
/** @private {?string} */
this.videoMime_ = video ? video.mimeType : null;
/** @private {?string} */
this.videoCodec_ = video ? video.codecs.split('.')[0] : null;
}
/**
* Check if this summaries is equal to another.
*
* @param {!shaka.util.ManifestFilter.VariantCodecSummary} other
* @return {boolean}
*/
equals(other) {
return this.audioMime_ == other.audioMime_ &&
this.audioCodec_ == other.audioCodec_ &&
this.videoMime_ == other.videoMime_ &&
this.videoCodec_ == other.videoCodec_;
}
};
/**
* @final
*/
shaka.util.ManifestFilter.VariantCodecSummarySet = class {
constructor() {
/** @private {!Array.<!shaka.util.ManifestFilter.VariantCodecSummary>} */
this.all_ = [];
}
/**
* @param {!shaka.util.ManifestFilter.VariantCodecSummary} summary
*/
add(summary) {
if (!this.contains(summary)) {
this.all_.push(summary);
}
}
/**
* Add all items from |other| to |this|.
* @param {!shaka.util.ManifestFilter.VariantCodecSummarySet} other
*/
includeAll(other) {
for (const item of other.all_) {
this.add(item);
}
}
/**
* Remove all items from |this| that are not in |other|.
* @param {!shaka.util.ManifestFilter.VariantCodecSummarySet} other
*/
onlyKeep(other) {
this.all_ = this.all_.filter((x) => other.contains(x));
}
/**
* @param {!shaka.util.ManifestFilter.VariantCodecSummary} summary
* @return {boolean}
*/
contains(summary) {
return this.all_.some((x) => summary.equals(x));
}
/**
* Create a set of variant codec summaries for a list of variants. The set
* may have fewer elements than the list if there are variants with similar
* codecs.
*
* @param {!Array.<shaka.extern.Variant>} variants
* @return {!shaka.util.ManifestFilter.VariantCodecSummarySet}
*/
static fromVariants(variants) {
const set = new shaka.util.ManifestFilter.VariantCodecSummarySet();
for (const variant of variants) {
set.add(new shaka.util.ManifestFilter.VariantCodecSummary(variant));
}
return set;
}
};