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feat(HLS): Get resolution from TS when load a Media Playlist (shaka-p…
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| /** | ||
| * @license | ||
| * Copyright Brightcove, 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. | ||
| */ | ||
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| goog.provide('shaka.util.ExpGolomb'); | ||
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| goog.require('shaka.util.DataViewReader'); | ||
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| /** | ||
| * @summary | ||
| * Parser for exponential Golomb codes, a variable-bitwidth number encoding | ||
| * scheme used by h264. | ||
| * Based on https://github.com/videojs/mux.js/blob/main/lib/utils/exp-golomb.js | ||
| * | ||
| * @export | ||
| */ | ||
| shaka.util.ExpGolomb = class { | ||
| /** | ||
| * @param {!Uint8Array} data | ||
| */ | ||
| constructor(data) { | ||
| /** @private {!Uint8Array} */ | ||
| this.data_ = data; | ||
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| /** @private {number} */ | ||
| this.workingBytesAvailable_ = data.byteLength; | ||
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| // the current word being examined | ||
| /** @private {number} */ | ||
| this.workingWord_ = 0; | ||
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| // the number of bits left to examine in the current word | ||
| /** @private {number} */ | ||
| this.workingBitsAvailable_ = 0; | ||
| } | ||
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| /** | ||
| * Load the next word | ||
| * | ||
| * @private | ||
| */ | ||
| loadWord_() { | ||
| const position = this.data_.byteLength - this.workingBytesAvailable_; | ||
| const bytes = new Uint8Array(4); | ||
| const availableBytes = Math.min(4, this.workingBytesAvailable_); | ||
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| if (availableBytes === 0) { | ||
| return; | ||
| } | ||
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| bytes.set(this.data_.subarray(position, position + availableBytes)); | ||
| const dataView = new shaka.util.DataViewReader( | ||
| bytes, shaka.util.DataViewReader.Endianness.BIG_ENDIAN); | ||
| this.workingWord_ = dataView.readUint32(); | ||
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| // track the amount of data that has been processed | ||
| this.workingBitsAvailable_ = availableBytes * 8; | ||
| this.workingBytesAvailable_ -= availableBytes; | ||
| } | ||
|
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| /** | ||
| * Skip n bits | ||
| * | ||
| * @param {number} count | ||
| */ | ||
| skipBits(count) { | ||
| if (this.workingBitsAvailable_ <= count) { | ||
| count -= this.workingBitsAvailable_; | ||
| const skipBytes = Math.floor(count / 8); | ||
| count -= (skipBytes * 8); | ||
| this.workingBitsAvailable_ -= skipBytes; | ||
| this.loadWord_(); | ||
| } | ||
| this.workingWord_ <<= count; | ||
| this.workingBitsAvailable_ -= count; | ||
| } | ||
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| /** | ||
| * Read n bits | ||
| * | ||
| * @param {number} size | ||
| * @return {number} | ||
| */ | ||
| readBits(size) { | ||
| let bits = Math.min(this.workingBitsAvailable_, size); | ||
| const valu = this.workingWord_ >>> (32 - bits); | ||
| this.workingBitsAvailable_ -= bits; | ||
| if (this.workingBitsAvailable_ > 0) { | ||
| this.workingWord_ <<= bits; | ||
| } else if (this.workingBytesAvailable_ > 0) { | ||
| this.loadWord_(); | ||
| } | ||
| bits = size - bits; | ||
| if (bits > 0) { | ||
| return (valu << bits) | this.readBits(bits); | ||
| } | ||
| return valu; | ||
| } | ||
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| /** | ||
| * Return the number of skip leading zeros | ||
| * | ||
| * @return {number} | ||
| * @private | ||
| */ | ||
| skipLeadingZeros_() { | ||
| let i; | ||
| for (i = 0; i < this.workingBitsAvailable_; ++i) { | ||
| if ((this.workingWord_ & (0x80000000 >>> i)) !== 0) { | ||
| // the first bit of working word is 1 | ||
| this.workingWord_ <<= i; | ||
| this.workingBitsAvailable_ -= i; | ||
| return i; | ||
| } | ||
| } | ||
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| // we exhausted workingWord and still have not found a 1 | ||
| this.loadWord_(); | ||
| return i + this.skipLeadingZeros_(); | ||
| } | ||
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| /** | ||
| * Skip exponential Golomb | ||
| */ | ||
| skipExpGolomb() { | ||
| this.skipBits(1 + this.skipLeadingZeros_()); | ||
| } | ||
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| /** | ||
| * Return unsigned exponential Golomb | ||
| * | ||
| * @return {number} | ||
| */ | ||
| readUnsignedExpGolomb() { | ||
| const clz = this.skipLeadingZeros_(); | ||
| return this.readBits(clz + 1) - 1; | ||
| } | ||
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| /** | ||
| * Return exponential Golomb | ||
| * | ||
| * @return {number} | ||
| */ | ||
| readExpGolomb() { | ||
| const valu = this.readUnsignedExpGolomb(); | ||
| if (0x01 & valu) { | ||
| // the number is odd if the low order bit is set | ||
| // add 1 to make it even, and divide by 2 | ||
| return (1 + valu) >>> 1; | ||
| } | ||
| // divide by two then make it negative | ||
| return -1 * (valu >>> 1); | ||
| } | ||
|
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| /** | ||
| * Read 1 bit as boolean | ||
| * | ||
| * @return {boolean} | ||
| */ | ||
| readBoolean() { | ||
| return this.readBits(1) === 1; | ||
| } | ||
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| /** | ||
| * Read 8 bits | ||
| * | ||
| * @return {number} | ||
| */ | ||
| readUnsignedByte() { | ||
| return this.readBits(8); | ||
| } | ||
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| /** | ||
| * The scaling list is optionally transmitted as part of a Sequence Parameter | ||
| * Set (SPS). | ||
| * | ||
| * @param {number} count the number of entries in this scaling list | ||
| * @see Recommendation ITU-T H.264, Section 7.3.2.1.1.1 | ||
| */ | ||
| skipScalingList(count) { | ||
| let lastScale = 8; | ||
| let nextScale = 8; | ||
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| for (let j = 0; j < count; j++) { | ||
| if (nextScale !== 0) { | ||
| const deltaScale = this.readExpGolomb(); | ||
| nextScale = (lastScale + deltaScale + 256) % 256; | ||
| } | ||
| lastScale = (nextScale === 0) ? lastScale : nextScale; | ||
| } | ||
| } | ||
| }; |
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