/*! @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 $xx xx
*/
const type = String.fromCharCode(data[0], data[1], data[2], data[3]);
const size = shaka.util.Id3Utils.readSize_(data, 4);
// skip frame id, size, and flags
const offset = 10;
return {
type,
size,
data: data.subarray(offset, offset + size),
};
}
/**
* @param {shaka.extern.MetadataRawFrame} frame
* @return {?shaka.extern.MetadataFrame}
* @private
*/
static decodeFrame_(frame) {
const BufferUtils = shaka.util.BufferUtils;
const StringUtils = shaka.util.StringUtils;
const metadataFrame = {
key: frame.type,
description: '',
data: '',
};
if (frame.type === 'TXXX') {
/*
* Format:
* [0] = {Text Encoding}
* [1-?] = {Description}\0{Value}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const descriptionEndIndex = frame.data.subarray(1).indexOf(0);
if (descriptionEndIndex === -1) {
return null;
}
const description = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 1, descriptionEndIndex));
const data = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 2 + descriptionEndIndex))
.replace(/\0*$/, '');
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*$/, '');
metadataFrame.description = description;
metadataFrame.data = data;
return metadataFrame;
} else if (frame.type === 'PRIV') {
/*
* Format: <text string>\0<binary data>
*/
if (frame.size < 2) {
return null;
}
const textEndIndex = frame.data.indexOf(0);
if (textEndIndex === -1) {
return null;
}
const text = StringUtils.fromUTF8(
BufferUtils.toUint8(frame.data, 0, textEndIndex));
const data = BufferUtils.toArrayBuffer(
frame.data.subarray(text.length + 1));
metadataFrame.description = text;
metadataFrame.data = data;
return metadataFrame;
} else if (frame.type[0] === 'T') {
/*
* Format:
* [0] = {Text Encoding}
* [1-?] = {Value}
*/
if (frame.size < 2) {
return null;
}
if (frame.data[0] !== shaka.util.Id3Utils.UTF8_encoding) {
shaka.log.warning('Ignore frame with unrecognized character ' +
'encoding');
return null;
}
const text = StringUtils.fromUTF8(frame.data.subarray(1))
.replace(/\0*$/, '');
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;
}
};
/**
* UTF8 encoding byte
* @const {number}
*/
shaka.util.Id3Utils.UTF8_encoding = 0x03;