shaka-player
Version:
DASH/EME video player library
403 lines (369 loc) • 11.4 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2022 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.util.Id3Utils');
goog.require('shaka.log');
goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.StringUtils');
/**
* @summary A set of Id3Utils utility functions.
* @export
*/
shaka.util.Id3Utils = class {
/**
* @param {Uint8Array} data
* @param {number} offset
* @return {boolean}
* @private
*/
static isHeader_(data, offset) {
/*
* http://id3.org/id3v2.3.0
* [0] = 'I'
* [1] = 'D'
* [2] = '3'
* [3,4] = {Version}
* [5] = {Flags}
* [6-9] = {ID3 Size}
*
* An ID3v2 tag can be detected with the following pattern:
* $49 44 33 yy yy xx zz zz zz zz
* Where yy is less than $FF, xx is the 'flags' byte and zz is less than $80
*/
if (offset + 10 <= data.length) {
// look for 'ID3' identifier
if (data[offset] === 0x49 &&
data[offset + 1] === 0x44 &&
data[offset + 2] === 0x33) {
// check version is within range
if (data[offset + 3] < 0xff && data[offset + 4] < 0xff) {
// check size is within range
if (data[offset + 6] < 0x80 &&
data[offset + 7] < 0x80 &&
data[offset + 8] < 0x80 &&
data[offset + 9] < 0x80) {
return true;
}
}
}
}
return false;
}
/**
* @param {Uint8Array} data
* @param {number} offset
* @return {boolean}
* @private
*/
static isFooter_(data, offset) {
/*
* The footer is a copy of the header, but with a different identifier
*/
if (offset + 10 <= data.length) {
// look for '3DI' identifier
if (data[offset] === 0x33 &&
data[offset + 1] === 0x44 &&
data[offset + 2] === 0x49) {
// check version is within range
if (data[offset + 3] < 0xff && data[offset + 4] < 0xff) {
// check size is within range
if (data[offset + 6] < 0x80 &&
data[offset + 7] < 0x80 &&
data[offset + 8] < 0x80 &&
data[offset + 9] < 0x80) {
return true;
}
}
}
}
return false;
}
/**
* @param {Uint8Array} data
* @param {number} offset
* @return {number}
* @private
*/
static readSize_(data, offset) {
let size = 0;
size = (data[offset] & 0x7f) << 21;
size |= (data[offset + 1] & 0x7f) << 14;
size |= (data[offset + 2] & 0x7f) << 7;
size |= data[offset + 3] & 0x7f;
return size;
}
/**
* @param {Uint8Array} data
* @return {shaka.extern.MetadataRawFrame}
* @private
*/
static getFrameData_(data) {
/*
* Frame ID $xx xx xx xx (four characters)
* Size $xx xx xx xx
* Flags $xx xx
*/
const type = String.fromCharCode(data[0], data[1], data[2], data[3]);
const size = shaka.util.Id3Utils.readSize_(data, 4);
// skip frame id, size, and flags
const offset = 10;
return {
type,
size,
data: data.subarray(offset, offset + size),
};
}
/**
* @param {shaka.extern.MetadataRawFrame} frame
* @return {?shaka.extern.MetadataFrame}
* @private
*/
static decodeFrame_(frame) {
const BufferUtils = shaka.util.BufferUtils;
const StringUtils = shaka.util.StringUtils;
const metadataFrame = {
key: frame.type,
description: '',
data: '',
mimeType: null,
pictureType: null,
};
if (frame.type === 'APIC') {
/*
* Format:
* [0] = {Text Encoding}
* [1 - X] = {MIME Type}\0
* [X+1] = {Picture Type}
* [X+2 - Y] = {Description}\0
* [Y - ?] = {Picture Data or Picture URL}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const mimeTypeEndIndex = frame.data.subarray(1).indexOf(0);
if (mimeTypeEndIndex === -1) {
return null;
}
const mimeType = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 1, mimeTypeEndIndex));
const pictureType = frame.data[2 + mimeTypeEndIndex];
const descriptionEndIndex = frame.data.subarray(3 + mimeTypeEndIndex)
.indexOf(0);
if (descriptionEndIndex === -1) {
return null;
}
const description = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 3 + mimeTypeEndIndex,
descriptionEndIndex));
let data;
if (mimeType === '-->') {
data = StringUtils.fromUTF8(
BufferUtils.toUint8(
frame.data, 4 + mimeTypeEndIndex + descriptionEndIndex));
} else {
data = BufferUtils.toArrayBuffer(
frame.data.subarray(4 + mimeTypeEndIndex + descriptionEndIndex));
}
metadataFrame.mimeType = mimeType;
metadataFrame.pictureType = pictureType;
metadataFrame.description = description;
metadataFrame.data = data;
return metadataFrame;
} else if (frame.type === 'TXXX') {
/*
* Format:
* [0] = {Text Encoding}
* [1-?] = {Description}\0{Value}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const descriptionEndIndex = frame.data.subarray(1).indexOf(0);
if (descriptionEndIndex === -1) {
return null;
}
const description = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 1, descriptionEndIndex));
const data = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 2 + descriptionEndIndex))
.replace(/\0*$/, '');
metadataFrame.description = description;
metadataFrame.data = data;
return metadataFrame;
} else if (frame.type === 'WXXX') {
/*
* Format:
* [0] = {Text Encoding}
* [1-?] = {Description}\0{URL}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const descriptionEndIndex = frame.data.subarray(1).indexOf(0);
if (descriptionEndIndex === -1) {
return null;
}
const description = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 1, descriptionEndIndex));
const data = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 2 + descriptionEndIndex))
.replace(/\0*$/, '');
metadataFrame.description = description;
metadataFrame.data = data;
return metadataFrame;
} else if (frame.type === 'PRIV') {
/*
* Format: <text string>\0<binary data>
*/
if (frame.size < 2) {
return null;
}
const textEndIndex = frame.data.indexOf(0);
if (textEndIndex === -1) {
return null;
}
const text = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 0, textEndIndex));
metadataFrame.description = text;
if (text == 'com.apple.streaming.transportStreamTimestamp') {
const data = frame.data.subarray(text.length + 1);
// timestamp is 33 bit expressed as a big-endian eight-octet number,
// with the upper 31 bits set to zero.
const pts33Bit = data[3] & 0x1;
let timestamp =
(data[4] << 23) + (data[5] << 15) + (data[6] << 7) + data[7];
timestamp /= 45;
if (pts33Bit) {
timestamp += 47721858.84;
} // 2^32 / 90
metadataFrame.data = timestamp;
} else {
const data = BufferUtils.toArrayBuffer(
frame.data.subarray(text.length + 1));
metadataFrame.data = data;
}
return metadataFrame;
} else if (frame.type[0] === 'T') {
/*
* Format:
* [0] = {Text Encoding}
* [1-?] = {Value}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const text = StringUtils.fromUTF8(frame.data.subarray(1))
.replace(/\0*$/, '');
metadataFrame.data = text;
return metadataFrame;
} else if (frame.type[0] === 'W') {
/*
* Format:
* [0-?] = {URL}
*/
const url = StringUtils.fromUTF8(frame.data)
.replace(/\0*$/, '');
metadataFrame.data = url;
return metadataFrame;
} else if (frame.data) {
shaka.log.warning('Unrecognized ID3 frame type:', frame.type);
metadataFrame.data = BufferUtils.toArrayBuffer(frame.data);
return metadataFrame;
}
return null;
}
/**
* Returns an array of ID3 frames found in all the ID3 tags in the id3Data
* @param {Uint8Array} id3Data - The ID3 data containing one or more ID3 tags
* @return {!Array<shaka.extern.MetadataFrame>}
* @export
*/
static getID3Frames(id3Data) {
const Id3Utils = shaka.util.Id3Utils;
let offset = 0;
const frames = [];
while (Id3Utils.isHeader_(id3Data, offset)) {
const size = Id3Utils.readSize_(id3Data, offset + 6);
if ((id3Data[offset + 5] >> 6) & 1) {
// skip extended header
offset += 10;
}
// skip past ID3 header
offset += 10;
const end = offset + size;
// loop through frames in the ID3 tag
while (offset + 10 < end) {
const frameData = Id3Utils.getFrameData_(id3Data.subarray(offset));
const frame = Id3Utils.decodeFrame_(frameData);
if (frame) {
frames.push(frame);
}
// skip frame header and frame data
offset += frameData.size + 10;
}
if (Id3Utils.isFooter_(id3Data, offset)) {
offset += 10;
}
}
return frames;
}
/**
* Returns any adjacent ID3 tags found in data starting at offset, as one
* block of data
* @param {Uint8Array} id3Data - The ID3 data containing one or more ID3 tags
* @param {number=} offset - The offset at which to start searching
* @return {!Uint8Array}
* @export
*/
static getID3Data(id3Data, offset = 0) {
const Id3Utils = shaka.util.Id3Utils;
const front = offset;
let length = 0;
while (Id3Utils.isHeader_(id3Data, offset)) {
if ((id3Data[offset + 5] >> 6) & 1) {
// skip extended header
length += 10;
}
// skip past ID3 header
length += 10;
const size = Id3Utils.readSize_(id3Data, offset + 6);
length += size;
if (Id3Utils.isFooter_(id3Data, offset + 10)) {
// ID3 footer is 10 bytes
length += 10;
}
offset += length;
}
if (length > 0) {
return id3Data.subarray(front, front + length);
}
return new Uint8Array([]);
}
};
/**
* UTF8 encoding byte
* @const {number}
*/
shaka.util.Id3Utils.UTF8_encoding = 0x03;