1905 lines
68 KiB
JavaScript
1905 lines
68 KiB
JavaScript
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
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/* Copyright 2012 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* globals ArithmeticDecoder, error, globalScope, log2, readUint16, readUint32,
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warn */
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'use strict';
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var JpxImage = (function JpxImageClosure() {
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// Table E.1
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var SubbandsGainLog2 = {
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'LL': 0,
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'LH': 1,
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'HL': 1,
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'HH': 2
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};
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function JpxImage() {
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this.failOnCorruptedImage = false;
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}
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JpxImage.prototype = {
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load: function JpxImage_load(url) {
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var xhr = new XMLHttpRequest();
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xhr.open('GET', url, true);
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xhr.responseType = 'arraybuffer';
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xhr.onload = (function() {
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// TODO catch parse error
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var data = new Uint8Array(xhr.response || xhr.mozResponseArrayBuffer);
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this.parse(data);
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if (this.onload) {
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this.onload();
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}
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}).bind(this);
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xhr.send(null);
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},
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parse: function JpxImage_parse(data) {
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var head = readUint16(data, 0);
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// No box header, immediate start of codestream (SOC)
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if (head === 0xFF4F) {
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this.parseCodestream(data, 0, data.length);
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return;
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}
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var position = 0, length = data.length;
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while (position < length) {
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var headerSize = 8;
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var lbox = readUint32(data, position);
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var tbox = readUint32(data, position + 4);
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position += headerSize;
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if (lbox === 1) {
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// XLBox: read UInt64 according to spec.
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// JavaScript's int precision of 53 bit should be sufficient here.
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lbox = readUint32(data, position) * 4294967296 +
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readUint32(data, position + 4);
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position += 8;
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headerSize += 8;
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}
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if (lbox === 0) {
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lbox = length - position + headerSize;
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}
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if (lbox < headerSize) {
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error('JPX error: Invalid box field size');
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}
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var dataLength = lbox - headerSize;
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var jumpDataLength = true;
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switch (tbox) {
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case 0x6A501A1A: // 'jP\032\032'
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// TODO
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break;
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case 0x6A703268: // 'jp2h'
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jumpDataLength = false; // parsing child boxes
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break;
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case 0x636F6C72: // 'colr'
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// TODO
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break;
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case 0x6A703263: // 'jp2c'
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this.parseCodestream(data, position, position + dataLength);
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break;
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}
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if (jumpDataLength) {
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position += dataLength;
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}
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}
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},
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parseImageProperties: function JpxImage_parseImageProperties(stream) {
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try {
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var newByte = stream.getByte();
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while (newByte >= 0) {
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var oldByte = newByte;
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newByte = stream.getByte();
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var code = (oldByte << 8) | newByte;
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// Image and tile size (SIZ)
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if (code == 0xFF51) {
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stream.skip(4);
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var Xsiz = stream.getInt32() >>> 0; // Byte 4
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var Ysiz = stream.getInt32() >>> 0; // Byte 8
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var XOsiz = stream.getInt32() >>> 0; // Byte 12
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var YOsiz = stream.getInt32() >>> 0; // Byte 16
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stream.skip(16);
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var Csiz = stream.getUint16(); // Byte 36
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this.width = Xsiz - XOsiz;
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this.height = Ysiz - YOsiz;
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this.componentsCount = Csiz;
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// Results are always returned as Uint8Arrays
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this.bitsPerComponent = 8;
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return;
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}
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}
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throw 'No size marker found in JPX stream';
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} catch (e) {
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if (this.failOnCorruptedImage) {
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error('JPX error: ' + e);
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} else {
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warn('JPX error: ' + e + '. Trying to recover');
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}
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}
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},
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parseCodestream: function JpxImage_parseCodestream(data, start, end) {
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var context = {};
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try {
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var position = start;
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while (position + 1 < end) {
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var code = readUint16(data, position);
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position += 2;
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var length = 0, j, sqcd, spqcds, spqcdSize, scalarExpounded, tile;
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switch (code) {
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case 0xFF4F: // Start of codestream (SOC)
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context.mainHeader = true;
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break;
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case 0xFFD9: // End of codestream (EOC)
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break;
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case 0xFF51: // Image and tile size (SIZ)
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length = readUint16(data, position);
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var siz = {};
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siz.Xsiz = readUint32(data, position + 4);
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siz.Ysiz = readUint32(data, position + 8);
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siz.XOsiz = readUint32(data, position + 12);
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siz.YOsiz = readUint32(data, position + 16);
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siz.XTsiz = readUint32(data, position + 20);
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siz.YTsiz = readUint32(data, position + 24);
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siz.XTOsiz = readUint32(data, position + 28);
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siz.YTOsiz = readUint32(data, position + 32);
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var componentsCount = readUint16(data, position + 36);
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siz.Csiz = componentsCount;
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var components = [];
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j = position + 38;
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for (var i = 0; i < componentsCount; i++) {
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var component = {
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precision: (data[j] & 0x7F) + 1,
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isSigned: !!(data[j] & 0x80),
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XRsiz: data[j + 1],
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YRsiz: data[j + 1]
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};
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calculateComponentDimensions(component, siz);
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components.push(component);
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}
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context.SIZ = siz;
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context.components = components;
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calculateTileGrids(context, components);
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context.QCC = [];
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context.COC = [];
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break;
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case 0xFF5C: // Quantization default (QCD)
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length = readUint16(data, position);
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var qcd = {};
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j = position + 2;
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sqcd = data[j++];
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switch (sqcd & 0x1F) {
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case 0:
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spqcdSize = 8;
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scalarExpounded = true;
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break;
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case 1:
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spqcdSize = 16;
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scalarExpounded = false;
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break;
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case 2:
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spqcdSize = 16;
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scalarExpounded = true;
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break;
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default:
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throw 'Invalid SQcd value ' + sqcd;
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}
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qcd.noQuantization = (spqcdSize == 8);
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qcd.scalarExpounded = scalarExpounded;
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qcd.guardBits = sqcd >> 5;
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spqcds = [];
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while (j < length + position) {
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var spqcd = {};
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if (spqcdSize == 8) {
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spqcd.epsilon = data[j++] >> 3;
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spqcd.mu = 0;
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} else {
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spqcd.epsilon = data[j] >> 3;
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spqcd.mu = ((data[j] & 0x7) << 8) | data[j + 1];
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j += 2;
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}
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spqcds.push(spqcd);
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}
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qcd.SPqcds = spqcds;
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if (context.mainHeader) {
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context.QCD = qcd;
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} else {
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context.currentTile.QCD = qcd;
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context.currentTile.QCC = [];
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}
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break;
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case 0xFF5D: // Quantization component (QCC)
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length = readUint16(data, position);
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var qcc = {};
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j = position + 2;
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var cqcc;
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if (context.SIZ.Csiz < 257) {
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cqcc = data[j++];
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} else {
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cqcc = readUint16(data, j);
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j += 2;
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}
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sqcd = data[j++];
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switch (sqcd & 0x1F) {
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case 0:
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spqcdSize = 8;
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scalarExpounded = true;
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break;
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case 1:
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spqcdSize = 16;
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scalarExpounded = false;
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break;
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case 2:
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spqcdSize = 16;
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scalarExpounded = true;
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break;
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default:
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throw 'Invalid SQcd value ' + sqcd;
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}
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qcc.noQuantization = (spqcdSize == 8);
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qcc.scalarExpounded = scalarExpounded;
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qcc.guardBits = sqcd >> 5;
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spqcds = [];
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while (j < (length + position)) {
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spqcd = {};
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if (spqcdSize == 8) {
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spqcd.epsilon = data[j++] >> 3;
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spqcd.mu = 0;
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} else {
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spqcd.epsilon = data[j] >> 3;
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spqcd.mu = ((data[j] & 0x7) << 8) | data[j + 1];
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j += 2;
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}
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spqcds.push(spqcd);
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}
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qcc.SPqcds = spqcds;
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if (context.mainHeader) {
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context.QCC[cqcc] = qcc;
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} else {
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context.currentTile.QCC[cqcc] = qcc;
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}
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break;
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case 0xFF52: // Coding style default (COD)
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length = readUint16(data, position);
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var cod = {};
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j = position + 2;
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var scod = data[j++];
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cod.entropyCoderWithCustomPrecincts = !!(scod & 1);
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cod.sopMarkerUsed = !!(scod & 2);
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cod.ephMarkerUsed = !!(scod & 4);
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cod.progressionOrder = data[j++];
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cod.layersCount = readUint16(data, j);
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j += 2;
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cod.multipleComponentTransform = data[j++];
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cod.decompositionLevelsCount = data[j++];
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cod.xcb = (data[j++] & 0xF) + 2;
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cod.ycb = (data[j++] & 0xF) + 2;
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var blockStyle = data[j++];
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cod.selectiveArithmeticCodingBypass = !!(blockStyle & 1);
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cod.resetContextProbabilities = !!(blockStyle & 2);
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cod.terminationOnEachCodingPass = !!(blockStyle & 4);
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cod.verticalyStripe = !!(blockStyle & 8);
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cod.predictableTermination = !!(blockStyle & 16);
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cod.segmentationSymbolUsed = !!(blockStyle & 32);
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cod.reversibleTransformation = data[j++];
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if (cod.entropyCoderWithCustomPrecincts) {
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var precinctsSizes = [];
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while (j < length + position) {
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var precinctsSize = data[j++];
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precinctsSizes.push({
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PPx: precinctsSize & 0xF,
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PPy: precinctsSize >> 4
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});
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}
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cod.precinctsSizes = precinctsSizes;
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}
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if (cod.sopMarkerUsed || cod.ephMarkerUsed ||
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cod.selectiveArithmeticCodingBypass ||
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cod.resetContextProbabilities ||
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cod.terminationOnEachCodingPass ||
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cod.verticalyStripe || cod.predictableTermination) {
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throw 'Unsupported COD options: ' +
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globalScope.JSON.stringify(cod);
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}
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if (context.mainHeader) {
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context.COD = cod;
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} else {
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context.currentTile.COD = cod;
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context.currentTile.COC = [];
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}
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break;
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case 0xFF90: // Start of tile-part (SOT)
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length = readUint16(data, position);
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tile = {};
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tile.index = readUint16(data, position + 2);
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tile.length = readUint32(data, position + 4);
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tile.dataEnd = tile.length + position - 2;
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tile.partIndex = data[position + 8];
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tile.partsCount = data[position + 9];
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context.mainHeader = false;
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if (tile.partIndex === 0) {
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// reset component specific settings
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tile.COD = context.COD;
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tile.COC = context.COC.slice(0); // clone of the global COC
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tile.QCD = context.QCD;
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tile.QCC = context.QCC.slice(0); // clone of the global COC
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}
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context.currentTile = tile;
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break;
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case 0xFF93: // Start of data (SOD)
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tile = context.currentTile;
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if (tile.partIndex === 0) {
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initializeTile(context, tile.index);
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buildPackets(context);
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}
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// moving to the end of the data
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length = tile.dataEnd - position;
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parseTilePackets(context, data, position, length);
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break;
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case 0xFF64: // Comment (COM)
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length = readUint16(data, position);
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// skipping content
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break;
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case 0xFF53: // Coding style component (COC)
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throw 'Codestream code 0xFF53 (COC) is not implemented';
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default:
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throw 'Unknown codestream code: ' + code.toString(16);
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}
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position += length;
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}
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} catch (e) {
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if (this.failOnCorruptedImage) {
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error('JPX error: ' + e);
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} else {
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warn('JPX error: ' + e + '. Trying to recover');
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}
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}
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this.tiles = transformComponents(context);
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this.width = context.SIZ.Xsiz - context.SIZ.XOsiz;
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this.height = context.SIZ.Ysiz - context.SIZ.YOsiz;
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this.componentsCount = context.SIZ.Csiz;
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}
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};
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function calculateComponentDimensions(component, siz) {
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// Section B.2 Component mapping
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component.x0 = Math.ceil(siz.XOsiz / component.XRsiz);
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component.x1 = Math.ceil(siz.Xsiz / component.XRsiz);
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component.y0 = Math.ceil(siz.YOsiz / component.YRsiz);
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component.y1 = Math.ceil(siz.Ysiz / component.YRsiz);
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component.width = component.x1 - component.x0;
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component.height = component.y1 - component.y0;
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}
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function calculateTileGrids(context, components) {
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var siz = context.SIZ;
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// Section B.3 Division into tile and tile-components
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var tile, tiles = [];
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var numXtiles = Math.ceil((siz.Xsiz - siz.XTOsiz) / siz.XTsiz);
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var numYtiles = Math.ceil((siz.Ysiz - siz.YTOsiz) / siz.YTsiz);
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for (var q = 0; q < numYtiles; q++) {
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for (var p = 0; p < numXtiles; p++) {
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tile = {};
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tile.tx0 = Math.max(siz.XTOsiz + p * siz.XTsiz, siz.XOsiz);
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tile.ty0 = Math.max(siz.YTOsiz + q * siz.YTsiz, siz.YOsiz);
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tile.tx1 = Math.min(siz.XTOsiz + (p + 1) * siz.XTsiz, siz.Xsiz);
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tile.ty1 = Math.min(siz.YTOsiz + (q + 1) * siz.YTsiz, siz.Ysiz);
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tile.width = tile.tx1 - tile.tx0;
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tile.height = tile.ty1 - tile.ty0;
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tile.components = [];
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tiles.push(tile);
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}
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}
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context.tiles = tiles;
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var componentsCount = siz.Csiz;
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for (var i = 0, ii = componentsCount; i < ii; i++) {
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var component = components[i];
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for (var j = 0, jj = tiles.length; j < jj; j++) {
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var tileComponent = {};
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tile = tiles[j];
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tileComponent.tcx0 = Math.ceil(tile.tx0 / component.XRsiz);
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tileComponent.tcy0 = Math.ceil(tile.ty0 / component.YRsiz);
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tileComponent.tcx1 = Math.ceil(tile.tx1 / component.XRsiz);
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tileComponent.tcy1 = Math.ceil(tile.ty1 / component.YRsiz);
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tileComponent.width = tileComponent.tcx1 - tileComponent.tcx0;
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tileComponent.height = tileComponent.tcy1 - tileComponent.tcy0;
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tile.components[i] = tileComponent;
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}
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}
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}
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function getBlocksDimensions(context, component, r) {
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var codOrCoc = component.codingStyleParameters;
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var result = {};
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if (!codOrCoc.entropyCoderWithCustomPrecincts) {
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result.PPx = 15;
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result.PPy = 15;
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} else {
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result.PPx = codOrCoc.precinctsSizes[r].PPx;
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result.PPy = codOrCoc.precinctsSizes[r].PPy;
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}
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// calculate codeblock size as described in section B.7
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result.xcb_ = (r > 0 ? Math.min(codOrCoc.xcb, result.PPx - 1) :
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Math.min(codOrCoc.xcb, result.PPx));
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result.ycb_ = (r > 0 ? Math.min(codOrCoc.ycb, result.PPy - 1) :
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Math.min(codOrCoc.ycb, result.PPy));
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return result;
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}
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function buildPrecincts(context, resolution, dimensions) {
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// Section B.6 Division resolution to precincts
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var precinctWidth = 1 << dimensions.PPx;
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var precinctHeight = 1 << dimensions.PPy;
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var numprecinctswide = (resolution.trx1 > resolution.trx0 ?
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Math.ceil(resolution.trx1 / precinctWidth) -
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Math.floor(resolution.trx0 / precinctWidth) : 0);
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var numprecinctshigh = (resolution.try1 > resolution.try0 ?
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Math.ceil(resolution.try1 / precinctHeight) -
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Math.floor(resolution.try0 / precinctHeight) : 0);
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var numprecincts = numprecinctswide * numprecinctshigh;
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var precinctXOffset = Math.floor(resolution.trx0 / precinctWidth) *
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precinctWidth;
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var precinctYOffset = Math.floor(resolution.try0 / precinctHeight) *
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precinctHeight;
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resolution.precinctParameters = {
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precinctXOffset: precinctXOffset,
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precinctYOffset: precinctYOffset,
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precinctWidth: precinctWidth,
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precinctHeight: precinctHeight,
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numprecinctswide: numprecinctswide,
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numprecinctshigh: numprecinctshigh,
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numprecincts: numprecincts
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};
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}
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function buildCodeblocks(context, subband, dimensions) {
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// Section B.7 Division sub-band into code-blocks
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var xcb_ = dimensions.xcb_;
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var ycb_ = dimensions.ycb_;
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var codeblockWidth = 1 << xcb_;
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var codeblockHeight = 1 << ycb_;
|
|
var cbx0 = subband.tbx0 >> xcb_;
|
|
var cby0 = subband.tby0 >> ycb_;
|
|
var cbx1 = (subband.tbx1 + codeblockWidth - 1) >> xcb_;
|
|
var cby1 = (subband.tby1 + codeblockHeight - 1) >> ycb_;
|
|
var precinctParameters = subband.resolution.precinctParameters;
|
|
var codeblocks = [];
|
|
var precincts = [];
|
|
var i, j, codeblock, precinctNumber;
|
|
for (j = cby0; j < cby1; j++) {
|
|
for (i = cbx0; i < cbx1; i++) {
|
|
codeblock = {
|
|
cbx: i,
|
|
cby: j,
|
|
tbx0: codeblockWidth * i,
|
|
tby0: codeblockHeight * j,
|
|
tbx1: codeblockWidth * (i + 1),
|
|
tby1: codeblockHeight * (j + 1)
|
|
};
|
|
// calculate precinct number
|
|
var pi = Math.floor((codeblock.tbx0 -
|
|
precinctParameters.precinctXOffset) /
|
|
precinctParameters.precinctWidth);
|
|
var pj = Math.floor((codeblock.tby0 -
|
|
precinctParameters.precinctYOffset) /
|
|
precinctParameters.precinctHeight);
|
|
precinctNumber = pj + pi * precinctParameters.numprecinctswide;
|
|
codeblock.tbx0_ = Math.max(subband.tbx0, codeblock.tbx0);
|
|
codeblock.tby0_ = Math.max(subband.tby0, codeblock.tby0);
|
|
codeblock.tbx1_ = Math.min(subband.tbx1, codeblock.tbx1);
|
|
codeblock.tby1_ = Math.min(subband.tby1, codeblock.tby1);
|
|
codeblock.precinctNumber = precinctNumber;
|
|
codeblock.subbandType = subband.type;
|
|
codeblock.Lblock = 3;
|
|
codeblocks.push(codeblock);
|
|
// building precinct for the sub-band
|
|
var precinct = precincts[precinctNumber];
|
|
if (precinct !== undefined) {
|
|
if (i < precinct.cbxMin) {
|
|
precinct.cbxMin = i;
|
|
} else if (i > precinct.cbxMax) {
|
|
precinct.cbxMax = i;
|
|
}
|
|
if (j < precinct.cbyMin) {
|
|
precinct.cbxMin = j;
|
|
} else if (j > precinct.cbyMax) {
|
|
precinct.cbyMax = j;
|
|
}
|
|
} else {
|
|
precincts[precinctNumber] = precinct = {
|
|
cbxMin: i,
|
|
cbyMin: j,
|
|
cbxMax: i,
|
|
cbyMax: j
|
|
};
|
|
}
|
|
codeblock.precinct = precinct;
|
|
}
|
|
}
|
|
subband.codeblockParameters = {
|
|
codeblockWidth: xcb_,
|
|
codeblockHeight: ycb_,
|
|
numcodeblockwide: cbx1 - cbx0 + 1,
|
|
numcodeblockhigh: cby1 - cby1 + 1
|
|
};
|
|
subband.codeblocks = codeblocks;
|
|
subband.precincts = precincts;
|
|
}
|
|
function createPacket(resolution, precinctNumber, layerNumber) {
|
|
var precinctCodeblocks = [];
|
|
// Section B.10.8 Order of info in packet
|
|
var subbands = resolution.subbands;
|
|
// sub-bands already ordered in 'LL', 'HL', 'LH', and 'HH' sequence
|
|
for (var i = 0, ii = subbands.length; i < ii; i++) {
|
|
var subband = subbands[i];
|
|
var codeblocks = subband.codeblocks;
|
|
for (var j = 0, jj = codeblocks.length; j < jj; j++) {
|
|
var codeblock = codeblocks[j];
|
|
if (codeblock.precinctNumber != precinctNumber) {
|
|
continue;
|
|
}
|
|
precinctCodeblocks.push(codeblock);
|
|
}
|
|
}
|
|
return {
|
|
layerNumber: layerNumber,
|
|
codeblocks: precinctCodeblocks
|
|
};
|
|
}
|
|
function LayerResolutionComponentPositionIterator(context) {
|
|
var siz = context.SIZ;
|
|
var tileIndex = context.currentTile.index;
|
|
var tile = context.tiles[tileIndex];
|
|
var layersCount = tile.codingStyleDefaultParameters.layersCount;
|
|
var componentsCount = siz.Csiz;
|
|
var maxDecompositionLevelsCount = 0;
|
|
for (var q = 0; q < componentsCount; q++) {
|
|
maxDecompositionLevelsCount = Math.max(maxDecompositionLevelsCount,
|
|
tile.components[q].codingStyleParameters.decompositionLevelsCount);
|
|
}
|
|
|
|
var l = 0, r = 0, i = 0, k = 0;
|
|
|
|
this.nextPacket = function JpxImage_nextPacket() {
|
|
// Section B.12.1.1 Layer-resolution-component-position
|
|
for (; l < layersCount; l++) {
|
|
for (; r <= maxDecompositionLevelsCount; r++) {
|
|
for (; i < componentsCount; i++) {
|
|
var component = tile.components[i];
|
|
if (r > component.codingStyleParameters.decompositionLevelsCount) {
|
|
continue;
|
|
}
|
|
|
|
var resolution = component.resolutions[r];
|
|
var numprecincts = resolution.precinctParameters.numprecincts;
|
|
for (; k < numprecincts;) {
|
|
var packet = createPacket(resolution, k, l);
|
|
k++;
|
|
return packet;
|
|
}
|
|
k = 0;
|
|
}
|
|
i = 0;
|
|
}
|
|
r = 0;
|
|
}
|
|
throw 'Out of packets';
|
|
};
|
|
}
|
|
function ResolutionLayerComponentPositionIterator(context) {
|
|
var siz = context.SIZ;
|
|
var tileIndex = context.currentTile.index;
|
|
var tile = context.tiles[tileIndex];
|
|
var layersCount = tile.codingStyleDefaultParameters.layersCount;
|
|
var componentsCount = siz.Csiz;
|
|
var maxDecompositionLevelsCount = 0;
|
|
for (var q = 0; q < componentsCount; q++) {
|
|
maxDecompositionLevelsCount = Math.max(maxDecompositionLevelsCount,
|
|
tile.components[q].codingStyleParameters.decompositionLevelsCount);
|
|
}
|
|
|
|
var r = 0, l = 0, i = 0, k = 0;
|
|
|
|
this.nextPacket = function JpxImage_nextPacket() {
|
|
// Section B.12.1.2 Resolution-layer-component-position
|
|
for (; r <= maxDecompositionLevelsCount; r++) {
|
|
for (; l < layersCount; l++) {
|
|
for (; i < componentsCount; i++) {
|
|
var component = tile.components[i];
|
|
if (r > component.codingStyleParameters.decompositionLevelsCount) {
|
|
continue;
|
|
}
|
|
|
|
var resolution = component.resolutions[r];
|
|
var numprecincts = resolution.precinctParameters.numprecincts;
|
|
for (; k < numprecincts;) {
|
|
var packet = createPacket(resolution, k, l);
|
|
k++;
|
|
return packet;
|
|
}
|
|
k = 0;
|
|
}
|
|
i = 0;
|
|
}
|
|
l = 0;
|
|
}
|
|
throw 'Out of packets';
|
|
};
|
|
}
|
|
function buildPackets(context) {
|
|
var siz = context.SIZ;
|
|
var tileIndex = context.currentTile.index;
|
|
var tile = context.tiles[tileIndex];
|
|
var componentsCount = siz.Csiz;
|
|
// Creating resolutions and sub-bands for each component
|
|
for (var c = 0; c < componentsCount; c++) {
|
|
var component = tile.components[c];
|
|
var decompositionLevelsCount =
|
|
component.codingStyleParameters.decompositionLevelsCount;
|
|
// Section B.5 Resolution levels and sub-bands
|
|
var resolutions = [];
|
|
var subbands = [];
|
|
for (var r = 0; r <= decompositionLevelsCount; r++) {
|
|
var blocksDimensions = getBlocksDimensions(context, component, r);
|
|
var resolution = {};
|
|
var scale = 1 << (decompositionLevelsCount - r);
|
|
resolution.trx0 = Math.ceil(component.tcx0 / scale);
|
|
resolution.try0 = Math.ceil(component.tcy0 / scale);
|
|
resolution.trx1 = Math.ceil(component.tcx1 / scale);
|
|
resolution.try1 = Math.ceil(component.tcy1 / scale);
|
|
buildPrecincts(context, resolution, blocksDimensions);
|
|
resolutions.push(resolution);
|
|
|
|
var subband;
|
|
if (r === 0) {
|
|
// one sub-band (LL) with last decomposition
|
|
subband = {};
|
|
subband.type = 'LL';
|
|
subband.tbx0 = Math.ceil(component.tcx0 / scale);
|
|
subband.tby0 = Math.ceil(component.tcy0 / scale);
|
|
subband.tbx1 = Math.ceil(component.tcx1 / scale);
|
|
subband.tby1 = Math.ceil(component.tcy1 / scale);
|
|
subband.resolution = resolution;
|
|
buildCodeblocks(context, subband, blocksDimensions);
|
|
subbands.push(subband);
|
|
resolution.subbands = [subband];
|
|
} else {
|
|
var bscale = 1 << (decompositionLevelsCount - r + 1);
|
|
var resolutionSubbands = [];
|
|
// three sub-bands (HL, LH and HH) with rest of decompositions
|
|
subband = {};
|
|
subband.type = 'HL';
|
|
subband.tbx0 = Math.ceil(component.tcx0 / bscale - 0.5);
|
|
subband.tby0 = Math.ceil(component.tcy0 / bscale);
|
|
subband.tbx1 = Math.ceil(component.tcx1 / bscale - 0.5);
|
|
subband.tby1 = Math.ceil(component.tcy1 / bscale);
|
|
subband.resolution = resolution;
|
|
buildCodeblocks(context, subband, blocksDimensions);
|
|
subbands.push(subband);
|
|
resolutionSubbands.push(subband);
|
|
|
|
subband = {};
|
|
subband.type = 'LH';
|
|
subband.tbx0 = Math.ceil(component.tcx0 / bscale);
|
|
subband.tby0 = Math.ceil(component.tcy0 / bscale - 0.5);
|
|
subband.tbx1 = Math.ceil(component.tcx1 / bscale);
|
|
subband.tby1 = Math.ceil(component.tcy1 / bscale - 0.5);
|
|
subband.resolution = resolution;
|
|
buildCodeblocks(context, subband, blocksDimensions);
|
|
subbands.push(subband);
|
|
resolutionSubbands.push(subband);
|
|
|
|
subband = {};
|
|
subband.type = 'HH';
|
|
subband.tbx0 = Math.ceil(component.tcx0 / bscale - 0.5);
|
|
subband.tby0 = Math.ceil(component.tcy0 / bscale - 0.5);
|
|
subband.tbx1 = Math.ceil(component.tcx1 / bscale - 0.5);
|
|
subband.tby1 = Math.ceil(component.tcy1 / bscale - 0.5);
|
|
subband.resolution = resolution;
|
|
buildCodeblocks(context, subband, blocksDimensions);
|
|
subbands.push(subband);
|
|
resolutionSubbands.push(subband);
|
|
|
|
resolution.subbands = resolutionSubbands;
|
|
}
|
|
}
|
|
component.resolutions = resolutions;
|
|
component.subbands = subbands;
|
|
}
|
|
// Generate the packets sequence
|
|
var progressionOrder = tile.codingStyleDefaultParameters.progressionOrder;
|
|
switch (progressionOrder) {
|
|
case 0:
|
|
tile.packetsIterator =
|
|
new LayerResolutionComponentPositionIterator(context);
|
|
break;
|
|
case 1:
|
|
tile.packetsIterator =
|
|
new ResolutionLayerComponentPositionIterator(context);
|
|
break;
|
|
default:
|
|
throw 'Unsupported progression order ' + progressionOrder;
|
|
}
|
|
}
|
|
function parseTilePackets(context, data, offset, dataLength) {
|
|
var position = 0;
|
|
var buffer, bufferSize = 0, skipNextBit = false;
|
|
function readBits(count) {
|
|
while (bufferSize < count) {
|
|
var b = data[offset + position];
|
|
position++;
|
|
if (skipNextBit) {
|
|
buffer = (buffer << 7) | b;
|
|
bufferSize += 7;
|
|
skipNextBit = false;
|
|
} else {
|
|
buffer = (buffer << 8) | b;
|
|
bufferSize += 8;
|
|
}
|
|
if (b == 0xFF) {
|
|
skipNextBit = true;
|
|
}
|
|
}
|
|
bufferSize -= count;
|
|
return (buffer >>> bufferSize) & ((1 << count) - 1);
|
|
}
|
|
function alignToByte() {
|
|
bufferSize = 0;
|
|
if (skipNextBit) {
|
|
position++;
|
|
skipNextBit = false;
|
|
}
|
|
}
|
|
function readCodingpasses() {
|
|
if (readBits(1) === 0) {
|
|
return 1;
|
|
}
|
|
if (readBits(1) === 0) {
|
|
return 2;
|
|
}
|
|
var value = readBits(2);
|
|
if (value < 3) {
|
|
return value + 3;
|
|
}
|
|
value = readBits(5);
|
|
if (value < 31) {
|
|
return value + 6;
|
|
}
|
|
value = readBits(7);
|
|
return value + 37;
|
|
}
|
|
var tileIndex = context.currentTile.index;
|
|
var tile = context.tiles[tileIndex];
|
|
var packetsIterator = tile.packetsIterator;
|
|
while (position < dataLength) {
|
|
var packet = packetsIterator.nextPacket();
|
|
if (!readBits(1)) {
|
|
alignToByte();
|
|
continue;
|
|
}
|
|
var layerNumber = packet.layerNumber;
|
|
var queue = [], codeblock;
|
|
for (var i = 0, ii = packet.codeblocks.length; i < ii; i++) {
|
|
codeblock = packet.codeblocks[i];
|
|
var precinct = codeblock.precinct;
|
|
var codeblockColumn = codeblock.cbx - precinct.cbxMin;
|
|
var codeblockRow = codeblock.cby - precinct.cbyMin;
|
|
var codeblockIncluded = false;
|
|
var firstTimeInclusion = false;
|
|
var valueReady;
|
|
if ('included' in codeblock) {
|
|
codeblockIncluded = !!readBits(1);
|
|
} else {
|
|
// reading inclusion tree
|
|
precinct = codeblock.precinct;
|
|
var inclusionTree, zeroBitPlanesTree;
|
|
if ('inclusionTree' in precinct) {
|
|
inclusionTree = precinct.inclusionTree;
|
|
} else {
|
|
// building inclusion and zero bit-planes trees
|
|
var width = precinct.cbxMax - precinct.cbxMin + 1;
|
|
var height = precinct.cbyMax - precinct.cbyMin + 1;
|
|
inclusionTree = new InclusionTree(width, height, layerNumber);
|
|
zeroBitPlanesTree = new TagTree(width, height);
|
|
precinct.inclusionTree = inclusionTree;
|
|
precinct.zeroBitPlanesTree = zeroBitPlanesTree;
|
|
}
|
|
|
|
if (inclusionTree.reset(codeblockColumn, codeblockRow, layerNumber)) {
|
|
while (true) {
|
|
if (readBits(1)) {
|
|
valueReady = !inclusionTree.nextLevel();
|
|
if (valueReady) {
|
|
codeblock.included = true;
|
|
codeblockIncluded = firstTimeInclusion = true;
|
|
break;
|
|
}
|
|
} else {
|
|
inclusionTree.incrementValue(layerNumber);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (!codeblockIncluded) {
|
|
continue;
|
|
}
|
|
if (firstTimeInclusion) {
|
|
zeroBitPlanesTree = precinct.zeroBitPlanesTree;
|
|
zeroBitPlanesTree.reset(codeblockColumn, codeblockRow);
|
|
while (true) {
|
|
if (readBits(1)) {
|
|
valueReady = !zeroBitPlanesTree.nextLevel();
|
|
if (valueReady) {
|
|
break;
|
|
}
|
|
} else {
|
|
zeroBitPlanesTree.incrementValue();
|
|
}
|
|
}
|
|
codeblock.zeroBitPlanes = zeroBitPlanesTree.value;
|
|
}
|
|
var codingpasses = readCodingpasses();
|
|
while (readBits(1)) {
|
|
codeblock.Lblock++;
|
|
}
|
|
var codingpassesLog2 = log2(codingpasses);
|
|
// rounding down log2
|
|
var bits = ((codingpasses < (1 << codingpassesLog2)) ?
|
|
codingpassesLog2 - 1 : codingpassesLog2) + codeblock.Lblock;
|
|
var codedDataLength = readBits(bits);
|
|
queue.push({
|
|
codeblock: codeblock,
|
|
codingpasses: codingpasses,
|
|
dataLength: codedDataLength
|
|
});
|
|
}
|
|
alignToByte();
|
|
while (queue.length > 0) {
|
|
var packetItem = queue.shift();
|
|
codeblock = packetItem.codeblock;
|
|
if (!('data' in codeblock)) {
|
|
codeblock.data = [];
|
|
}
|
|
codeblock.data.push({
|
|
data: data,
|
|
start: offset + position,
|
|
end: offset + position + packetItem.dataLength,
|
|
codingpasses: packetItem.codingpasses
|
|
});
|
|
position += packetItem.dataLength;
|
|
}
|
|
}
|
|
return position;
|
|
}
|
|
function copyCoefficients(coefficients, levelWidth, levelHeight, subband,
|
|
delta, mb, reversible, segmentationSymbolUsed) {
|
|
var x0 = subband.tbx0;
|
|
var y0 = subband.tby0;
|
|
var width = subband.tbx1 - subband.tbx0;
|
|
var codeblocks = subband.codeblocks;
|
|
var right = subband.type.charAt(0) === 'H' ? 1 : 0;
|
|
var bottom = subband.type.charAt(1) === 'H' ? levelWidth : 0;
|
|
|
|
for (var i = 0, ii = codeblocks.length; i < ii; ++i) {
|
|
var codeblock = codeblocks[i];
|
|
var blockWidth = codeblock.tbx1_ - codeblock.tbx0_;
|
|
var blockHeight = codeblock.tby1_ - codeblock.tby0_;
|
|
if (blockWidth === 0 || blockHeight === 0) {
|
|
continue;
|
|
}
|
|
if (!('data' in codeblock)) {
|
|
continue;
|
|
}
|
|
|
|
var bitModel, currentCodingpassType;
|
|
bitModel = new BitModel(blockWidth, blockHeight, codeblock.subbandType,
|
|
codeblock.zeroBitPlanes, mb);
|
|
currentCodingpassType = 2; // first bit plane starts from cleanup
|
|
|
|
// collect data
|
|
var data = codeblock.data, totalLength = 0, codingpasses = 0;
|
|
var j, jj, dataItem;
|
|
for (j = 0, jj = data.length; j < jj; j++) {
|
|
dataItem = data[j];
|
|
totalLength += dataItem.end - dataItem.start;
|
|
codingpasses += dataItem.codingpasses;
|
|
}
|
|
var encodedData = new Uint8Array(totalLength);
|
|
var position = 0;
|
|
for (j = 0, jj = data.length; j < jj; j++) {
|
|
dataItem = data[j];
|
|
var chunk = dataItem.data.subarray(dataItem.start, dataItem.end);
|
|
encodedData.set(chunk, position);
|
|
position += chunk.length;
|
|
}
|
|
// decoding the item
|
|
var decoder = new ArithmeticDecoder(encodedData, 0, totalLength);
|
|
bitModel.setDecoder(decoder);
|
|
|
|
for (j = 0; j < codingpasses; j++) {
|
|
switch (currentCodingpassType) {
|
|
case 0:
|
|
bitModel.runSignificancePropogationPass();
|
|
break;
|
|
case 1:
|
|
bitModel.runMagnitudeRefinementPass();
|
|
break;
|
|
case 2:
|
|
bitModel.runCleanupPass();
|
|
if (segmentationSymbolUsed) {
|
|
bitModel.checkSegmentationSymbol();
|
|
}
|
|
break;
|
|
}
|
|
currentCodingpassType = (currentCodingpassType + 1) % 3;
|
|
}
|
|
|
|
var offset = (codeblock.tbx0_ - x0) + (codeblock.tby0_ - y0) * width;
|
|
var sign = bitModel.coefficentsSign;
|
|
var magnitude = bitModel.coefficentsMagnitude;
|
|
var bitsDecoded = bitModel.bitsDecoded;
|
|
var magnitudeCorrection = reversible ? 0 : 0.5;
|
|
var k, n, nb;
|
|
position = 0;
|
|
// Do the interleaving of Section F.3.3 here, so we do not need
|
|
// to copy later. LL level is not interleaved, just copied.
|
|
var interleave = (subband.type !== 'LL');
|
|
for (j = 0; j < blockHeight; j++) {
|
|
var row = (offset / width) | 0; // row in the non-interleaved subband
|
|
var levelOffset = 2 * row * (levelWidth - width) + right + bottom;
|
|
for (k = 0; k < blockWidth; k++) {
|
|
n = magnitude[position];
|
|
if (n !== 0) {
|
|
n = (n + magnitudeCorrection) * delta;
|
|
if (sign[position] !== 0) {
|
|
n = -n;
|
|
}
|
|
nb = bitsDecoded[position];
|
|
var pos = interleave ? (levelOffset + (offset << 1)) : offset;
|
|
if (reversible && (nb >= mb)) {
|
|
coefficients[pos] = n;
|
|
} else {
|
|
coefficients[pos] = n * (1 << (mb - nb));
|
|
}
|
|
}
|
|
offset++;
|
|
position++;
|
|
}
|
|
offset += width - blockWidth;
|
|
}
|
|
}
|
|
}
|
|
function transformTile(context, tile, c) {
|
|
var component = tile.components[c];
|
|
var codingStyleParameters = component.codingStyleParameters;
|
|
var quantizationParameters = component.quantizationParameters;
|
|
var decompositionLevelsCount =
|
|
codingStyleParameters.decompositionLevelsCount;
|
|
var spqcds = quantizationParameters.SPqcds;
|
|
var scalarExpounded = quantizationParameters.scalarExpounded;
|
|
var guardBits = quantizationParameters.guardBits;
|
|
var segmentationSymbolUsed = codingStyleParameters.segmentationSymbolUsed;
|
|
var precision = context.components[c].precision;
|
|
|
|
var reversible = codingStyleParameters.reversibleTransformation;
|
|
var transform = (reversible ? new ReversibleTransform() :
|
|
new IrreversibleTransform());
|
|
|
|
var subbandCoefficients = [];
|
|
var b = 0;
|
|
for (var i = 0; i <= decompositionLevelsCount; i++) {
|
|
var resolution = component.resolutions[i];
|
|
|
|
var width = resolution.trx1 - resolution.trx0;
|
|
var height = resolution.try1 - resolution.try0;
|
|
// Allocate space for the whole sublevel.
|
|
var coefficients = new Float32Array(width * height);
|
|
|
|
for (var j = 0, jj = resolution.subbands.length; j < jj; j++) {
|
|
var mu, epsilon;
|
|
if (!scalarExpounded) {
|
|
// formula E-5
|
|
mu = spqcds[0].mu;
|
|
epsilon = spqcds[0].epsilon + (i > 0 ? 1 - i : 0);
|
|
} else {
|
|
mu = spqcds[b].mu;
|
|
epsilon = spqcds[b].epsilon;
|
|
b++;
|
|
}
|
|
|
|
var subband = resolution.subbands[j];
|
|
var gainLog2 = SubbandsGainLog2[subband.type];
|
|
|
|
// calulate quantization coefficient (Section E.1.1.1)
|
|
var delta = (reversible ? 1 :
|
|
Math.pow(2, precision + gainLog2 - epsilon) * (1 + mu / 2048));
|
|
var mb = (guardBits + epsilon - 1);
|
|
|
|
// In the first resolution level, copyCoefficients will fill the
|
|
// whole array with coefficients. In the succeding passes,
|
|
// copyCoefficients will consecutively fill in the values that belong
|
|
// to the interleaved positions of the HL, LH, and HH coefficients.
|
|
// The LL coefficients will then be interleaved in Transform.iterate().
|
|
copyCoefficients(coefficients, width, height, subband, delta, mb,
|
|
reversible, segmentationSymbolUsed);
|
|
}
|
|
subbandCoefficients.push({
|
|
width: width,
|
|
height: height,
|
|
items: coefficients
|
|
});
|
|
}
|
|
|
|
var result = transform.calculate(subbandCoefficients,
|
|
component.tcx0, component.tcy0);
|
|
return {
|
|
left: component.tcx0,
|
|
top: component.tcy0,
|
|
width: result.width,
|
|
height: result.height,
|
|
items: result.items
|
|
};
|
|
}
|
|
function transformComponents(context) {
|
|
var siz = context.SIZ;
|
|
var components = context.components;
|
|
var componentsCount = siz.Csiz;
|
|
var resultImages = [];
|
|
for (var i = 0, ii = context.tiles.length; i < ii; i++) {
|
|
var tile = context.tiles[i];
|
|
var transformedTiles = [];
|
|
var c;
|
|
for (c = 0; c < componentsCount; c++) {
|
|
transformedTiles[c] = transformTile(context, tile, c);
|
|
}
|
|
var tile0 = transformedTiles[0];
|
|
var out = new Uint8Array(tile0.items.length * componentsCount);
|
|
var result = {
|
|
left: tile0.left,
|
|
top: tile0.top,
|
|
width: tile0.width,
|
|
height: tile0.height,
|
|
items: out
|
|
};
|
|
|
|
// Section G.2.2 Inverse multi component transform
|
|
var shift, offset, max, min;
|
|
var pos = 0, j, jj, y0, y1, y2, r, g, b, k, val;
|
|
if (tile.codingStyleDefaultParameters.multipleComponentTransform) {
|
|
var fourComponents = componentsCount === 4;
|
|
var y0items = transformedTiles[0].items;
|
|
var y1items = transformedTiles[1].items;
|
|
var y2items = transformedTiles[2].items;
|
|
var y3items = fourComponents ? transformedTiles[3].items : null;
|
|
|
|
// HACK: The multiple component transform formulas below assume that
|
|
// all components have the same precision. With this in mind, we
|
|
// compute shift and offset only once.
|
|
shift = components[0].precision - 8;
|
|
offset = (128 << shift) + 0.5;
|
|
max = (127.5 * (1 << shift));
|
|
min = -max;
|
|
|
|
var component0 = tile.components[0];
|
|
if (!component0.codingStyleParameters.reversibleTransformation) {
|
|
// inverse irreversible multiple component transform
|
|
for (j = 0, jj = y0items.length; j < jj; ++j) {
|
|
y0 = y0items[j];
|
|
y1 = y1items[j];
|
|
y2 = y2items[j];
|
|
r = y0 + 1.402 * y2;
|
|
g = y0 - 0.34413 * y1 - 0.71414 * y2;
|
|
b = y0 + 1.772 * y1;
|
|
out[pos++] = r <= min ? 0 : r >= max ? 255 : (r + offset) >> shift;
|
|
out[pos++] = g <= min ? 0 : g >= max ? 255 : (g + offset) >> shift;
|
|
out[pos++] = b <= min ? 0 : b >= max ? 255 : (b + offset) >> shift;
|
|
if (fourComponents) {
|
|
k = y3items[j];
|
|
out[pos++] =
|
|
k <= min ? 0 : k >= max ? 255 : (k + offset) >> shift;
|
|
}
|
|
}
|
|
} else {
|
|
// inverse reversible multiple component transform
|
|
for (j = 0, jj = y0items.length; j < jj; ++j) {
|
|
y0 = y0items[j];
|
|
y1 = y1items[j];
|
|
y2 = y2items[j];
|
|
g = y0 - ((y2 + y1) >> 2);
|
|
r = g + y2;
|
|
b = g + y1;
|
|
out[pos++] = r <= min ? 0 : r >= max ? 255 : (r + offset) >> shift;
|
|
out[pos++] = g <= min ? 0 : g >= max ? 255 : (g + offset) >> shift;
|
|
out[pos++] = b <= min ? 0 : b >= max ? 255 : (b + offset) >> shift;
|
|
if (fourComponents) {
|
|
k = y3items[j];
|
|
out[pos++] =
|
|
k <= min ? 0 : k >= max ? 255 : (k + offset) >> shift;
|
|
}
|
|
}
|
|
}
|
|
} else { // no multi-component transform
|
|
for (c = 0; c < componentsCount; c++) {
|
|
var items = transformedTiles[c].items;
|
|
shift = components[c].precision - 8;
|
|
offset = (128 << shift) + 0.5;
|
|
max = (127.5 * (1 << shift));
|
|
min = -max;
|
|
for (pos = c, j = 0, jj = items.length; j < jj; j++) {
|
|
val = items[j];
|
|
out[pos] = val <= min ? 0 :
|
|
val >= max ? 255 : (val + offset) >> shift;
|
|
pos += componentsCount;
|
|
}
|
|
}
|
|
}
|
|
resultImages.push(result);
|
|
}
|
|
return resultImages;
|
|
}
|
|
function initializeTile(context, tileIndex) {
|
|
var siz = context.SIZ;
|
|
var componentsCount = siz.Csiz;
|
|
var tile = context.tiles[tileIndex];
|
|
for (var c = 0; c < componentsCount; c++) {
|
|
var component = tile.components[c];
|
|
var qcdOrQcc = (c in context.currentTile.QCC ?
|
|
context.currentTile.QCC[c] : context.currentTile.QCD);
|
|
component.quantizationParameters = qcdOrQcc;
|
|
var codOrCoc = (c in context.currentTile.COC ?
|
|
context.currentTile.COC[c] : context.currentTile.COD);
|
|
component.codingStyleParameters = codOrCoc;
|
|
}
|
|
tile.codingStyleDefaultParameters = context.currentTile.COD;
|
|
}
|
|
|
|
// Section B.10.2 Tag trees
|
|
var TagTree = (function TagTreeClosure() {
|
|
function TagTree(width, height) {
|
|
var levelsLength = log2(Math.max(width, height)) + 1;
|
|
this.levels = [];
|
|
for (var i = 0; i < levelsLength; i++) {
|
|
var level = {
|
|
width: width,
|
|
height: height,
|
|
items: []
|
|
};
|
|
this.levels.push(level);
|
|
width = Math.ceil(width / 2);
|
|
height = Math.ceil(height / 2);
|
|
}
|
|
}
|
|
TagTree.prototype = {
|
|
reset: function TagTree_reset(i, j) {
|
|
var currentLevel = 0, value = 0, level;
|
|
while (currentLevel < this.levels.length) {
|
|
level = this.levels[currentLevel];
|
|
var index = i + j * level.width;
|
|
if (index in level.items) {
|
|
value = level.items[index];
|
|
break;
|
|
}
|
|
level.index = index;
|
|
i >>= 1;
|
|
j >>= 1;
|
|
currentLevel++;
|
|
}
|
|
currentLevel--;
|
|
level = this.levels[currentLevel];
|
|
level.items[level.index] = value;
|
|
this.currentLevel = currentLevel;
|
|
delete this.value;
|
|
},
|
|
incrementValue: function TagTree_incrementValue() {
|
|
var level = this.levels[this.currentLevel];
|
|
level.items[level.index]++;
|
|
},
|
|
nextLevel: function TagTree_nextLevel() {
|
|
var currentLevel = this.currentLevel;
|
|
var level = this.levels[currentLevel];
|
|
var value = level.items[level.index];
|
|
currentLevel--;
|
|
if (currentLevel < 0) {
|
|
this.value = value;
|
|
return false;
|
|
}
|
|
|
|
this.currentLevel = currentLevel;
|
|
level = this.levels[currentLevel];
|
|
level.items[level.index] = value;
|
|
return true;
|
|
}
|
|
};
|
|
return TagTree;
|
|
})();
|
|
|
|
var InclusionTree = (function InclusionTreeClosure() {
|
|
function InclusionTree(width, height, defaultValue) {
|
|
var levelsLength = log2(Math.max(width, height)) + 1;
|
|
this.levels = [];
|
|
for (var i = 0; i < levelsLength; i++) {
|
|
var items = new Uint8Array(width * height);
|
|
for (var j = 0, jj = items.length; j < jj; j++) {
|
|
items[j] = defaultValue;
|
|
}
|
|
|
|
var level = {
|
|
width: width,
|
|
height: height,
|
|
items: items
|
|
};
|
|
this.levels.push(level);
|
|
|
|
width = Math.ceil(width / 2);
|
|
height = Math.ceil(height / 2);
|
|
}
|
|
}
|
|
InclusionTree.prototype = {
|
|
reset: function InclusionTree_reset(i, j, stopValue) {
|
|
var currentLevel = 0;
|
|
while (currentLevel < this.levels.length) {
|
|
var level = this.levels[currentLevel];
|
|
var index = i + j * level.width;
|
|
level.index = index;
|
|
var value = level.items[index];
|
|
|
|
if (value == 0xFF) {
|
|
break;
|
|
}
|
|
|
|
if (value > stopValue) {
|
|
this.currentLevel = currentLevel;
|
|
// already know about this one, propagating the value to top levels
|
|
this.propagateValues();
|
|
return false;
|
|
}
|
|
|
|
i >>= 1;
|
|
j >>= 1;
|
|
currentLevel++;
|
|
}
|
|
this.currentLevel = currentLevel - 1;
|
|
return true;
|
|
},
|
|
incrementValue: function InclusionTree_incrementValue(stopValue) {
|
|
var level = this.levels[this.currentLevel];
|
|
level.items[level.index] = stopValue + 1;
|
|
this.propagateValues();
|
|
},
|
|
propagateValues: function InclusionTree_propagateValues() {
|
|
var levelIndex = this.currentLevel;
|
|
var level = this.levels[levelIndex];
|
|
var currentValue = level.items[level.index];
|
|
while (--levelIndex >= 0) {
|
|
level = this.levels[levelIndex];
|
|
level.items[level.index] = currentValue;
|
|
}
|
|
},
|
|
nextLevel: function InclusionTree_nextLevel() {
|
|
var currentLevel = this.currentLevel;
|
|
var level = this.levels[currentLevel];
|
|
var value = level.items[level.index];
|
|
level.items[level.index] = 0xFF;
|
|
currentLevel--;
|
|
if (currentLevel < 0) {
|
|
return false;
|
|
}
|
|
|
|
this.currentLevel = currentLevel;
|
|
level = this.levels[currentLevel];
|
|
level.items[level.index] = value;
|
|
return true;
|
|
}
|
|
};
|
|
return InclusionTree;
|
|
})();
|
|
|
|
// Section D. Coefficient bit modeling
|
|
var BitModel = (function BitModelClosure() {
|
|
var UNIFORM_CONTEXT = 17;
|
|
var RUNLENGTH_CONTEXT = 18;
|
|
// Table D-1
|
|
// The index is binary presentation: 0dddvvhh, ddd - sum of Di (0..4),
|
|
// vv - sum of Vi (0..2), and hh - sum of Hi (0..2)
|
|
var LLAndLHContextsLabel = new Uint8Array([
|
|
0, 5, 8, 0, 3, 7, 8, 0, 4, 7, 8, 0, 0, 0, 0, 0, 1, 6, 8, 0, 3, 7, 8, 0, 4,
|
|
7, 8, 0, 0, 0, 0, 0, 2, 6, 8, 0, 3, 7, 8, 0, 4, 7, 8, 0, 0, 0, 0, 0, 2, 6,
|
|
8, 0, 3, 7, 8, 0, 4, 7, 8, 0, 0, 0, 0, 0, 2, 6, 8, 0, 3, 7, 8, 0, 4, 7, 8
|
|
]);
|
|
var HLContextLabel = new Uint8Array([
|
|
0, 3, 4, 0, 5, 7, 7, 0, 8, 8, 8, 0, 0, 0, 0, 0, 1, 3, 4, 0, 6, 7, 7, 0, 8,
|
|
8, 8, 0, 0, 0, 0, 0, 2, 3, 4, 0, 6, 7, 7, 0, 8, 8, 8, 0, 0, 0, 0, 0, 2, 3,
|
|
4, 0, 6, 7, 7, 0, 8, 8, 8, 0, 0, 0, 0, 0, 2, 3, 4, 0, 6, 7, 7, 0, 8, 8, 8
|
|
]);
|
|
var HHContextLabel = new Uint8Array([
|
|
0, 1, 2, 0, 1, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 0, 3, 4, 5, 0, 4, 5, 5, 0, 5,
|
|
5, 5, 0, 0, 0, 0, 0, 6, 7, 7, 0, 7, 7, 7, 0, 7, 7, 7, 0, 0, 0, 0, 0, 8, 8,
|
|
8, 0, 8, 8, 8, 0, 8, 8, 8, 0, 0, 0, 0, 0, 8, 8, 8, 0, 8, 8, 8, 0, 8, 8, 8
|
|
]);
|
|
|
|
function BitModel(width, height, subband, zeroBitPlanes, mb) {
|
|
this.width = width;
|
|
this.height = height;
|
|
|
|
this.contextLabelTable = (subband == 'HH' ? HHContextLabel :
|
|
(subband == 'HL' ? HLContextLabel : LLAndLHContextsLabel));
|
|
|
|
var coefficientCount = width * height;
|
|
|
|
// coefficients outside the encoding region treated as insignificant
|
|
// add border state cells for significanceState
|
|
this.neighborsSignificance = new Uint8Array(coefficientCount);
|
|
this.coefficentsSign = new Uint8Array(coefficientCount);
|
|
this.coefficentsMagnitude = mb > 14 ? new Uint32Array(coefficientCount) :
|
|
mb > 6 ? new Uint16Array(coefficientCount) :
|
|
new Uint8Array(coefficientCount);
|
|
this.processingFlags = new Uint8Array(coefficientCount);
|
|
|
|
var bitsDecoded = new Uint8Array(coefficientCount);
|
|
if (zeroBitPlanes !== 0) {
|
|
for (var i = 0; i < coefficientCount; i++) {
|
|
bitsDecoded[i] = zeroBitPlanes;
|
|
}
|
|
}
|
|
this.bitsDecoded = bitsDecoded;
|
|
|
|
this.reset();
|
|
}
|
|
|
|
BitModel.prototype = {
|
|
setDecoder: function BitModel_setDecoder(decoder) {
|
|
this.decoder = decoder;
|
|
},
|
|
reset: function BitModel_reset() {
|
|
// We have 17 contexts that are accessed via context labels,
|
|
// plus the uniform and runlength context.
|
|
this.contexts = new Int8Array(19);
|
|
|
|
// Contexts are packed into 1 byte:
|
|
// highest 7 bits carry the index, lowest bit carries mps
|
|
this.contexts[0] = (4 << 1) | 0;
|
|
this.contexts[UNIFORM_CONTEXT] = (46 << 1) | 0;
|
|
this.contexts[RUNLENGTH_CONTEXT] = (3 << 1) | 0;
|
|
},
|
|
setNeighborsSignificance:
|
|
function BitModel_setNeighborsSignificance(row, column, index) {
|
|
var neighborsSignificance = this.neighborsSignificance;
|
|
var width = this.width, height = this.height;
|
|
var left = (column > 0);
|
|
var right = (column + 1 < width);
|
|
var i;
|
|
|
|
if (row > 0) {
|
|
i = index - width;
|
|
if (left) {
|
|
neighborsSignificance[i - 1] += 0x10;
|
|
}
|
|
if (right) {
|
|
neighborsSignificance[i + 1] += 0x10;
|
|
}
|
|
neighborsSignificance[i] += 0x04;
|
|
}
|
|
|
|
if (row + 1 < height) {
|
|
i = index + width;
|
|
if (left) {
|
|
neighborsSignificance[i - 1] += 0x10;
|
|
}
|
|
if (right) {
|
|
neighborsSignificance[i + 1] += 0x10;
|
|
}
|
|
neighborsSignificance[i] += 0x04;
|
|
}
|
|
|
|
if (left) {
|
|
neighborsSignificance[index - 1] += 0x01;
|
|
}
|
|
if (right) {
|
|
neighborsSignificance[index + 1] += 0x01;
|
|
}
|
|
neighborsSignificance[index] |= 0x80;
|
|
},
|
|
runSignificancePropogationPass:
|
|
function BitModel_runSignificancePropogationPass() {
|
|
var decoder = this.decoder;
|
|
var width = this.width, height = this.height;
|
|
var coefficentsMagnitude = this.coefficentsMagnitude;
|
|
var coefficentsSign = this.coefficentsSign;
|
|
var neighborsSignificance = this.neighborsSignificance;
|
|
var processingFlags = this.processingFlags;
|
|
var contexts = this.contexts;
|
|
var labels = this.contextLabelTable;
|
|
var bitsDecoded = this.bitsDecoded;
|
|
var processedInverseMask = ~1;
|
|
var processedMask = 1;
|
|
var firstMagnitudeBitMask = 2;
|
|
|
|
for (var i0 = 0; i0 < height; i0 += 4) {
|
|
for (var j = 0; j < width; j++) {
|
|
var index = i0 * width + j;
|
|
for (var i1 = 0; i1 < 4; i1++, index += width) {
|
|
var i = i0 + i1;
|
|
if (i >= height) {
|
|
break;
|
|
}
|
|
// clear processed flag first
|
|
processingFlags[index] &= processedInverseMask;
|
|
|
|
if (coefficentsMagnitude[index] ||
|
|
!neighborsSignificance[index]) {
|
|
continue;
|
|
}
|
|
|
|
var contextLabel = labels[neighborsSignificance[index]];
|
|
var decision = decoder.readBit(contexts, contextLabel);
|
|
if (decision) {
|
|
var sign = this.decodeSignBit(i, j, index);
|
|
coefficentsSign[index] = sign;
|
|
coefficentsMagnitude[index] = 1;
|
|
this.setNeighborsSignificance(i, j, index);
|
|
processingFlags[index] |= firstMagnitudeBitMask;
|
|
}
|
|
bitsDecoded[index]++;
|
|
processingFlags[index] |= processedMask;
|
|
}
|
|
}
|
|
}
|
|
},
|
|
decodeSignBit: function BitModel_decodeSignBit(row, column, index) {
|
|
var width = this.width, height = this.height;
|
|
var coefficentsMagnitude = this.coefficentsMagnitude;
|
|
var coefficentsSign = this.coefficentsSign;
|
|
var contribution, sign0, sign1, significance1;
|
|
var contextLabel, decoded;
|
|
|
|
// calculate horizontal contribution
|
|
significance1 = (column > 0 && coefficentsMagnitude[index - 1] !== 0);
|
|
if (column + 1 < width && coefficentsMagnitude[index + 1] !== 0) {
|
|
sign1 = coefficentsSign[index + 1];
|
|
if (significance1) {
|
|
sign0 = coefficentsSign[index - 1];
|
|
contribution = 1 - sign1 - sign0;
|
|
} else {
|
|
contribution = 1 - sign1 - sign1;
|
|
}
|
|
} else if (significance1) {
|
|
sign0 = coefficentsSign[index - 1];
|
|
contribution = 1 - sign0 - sign0;
|
|
} else {
|
|
contribution = 0;
|
|
}
|
|
var horizontalContribution = 3 * contribution;
|
|
|
|
// calculate vertical contribution and combine with the horizontal
|
|
significance1 = (row > 0 && coefficentsMagnitude[index - width] !== 0);
|
|
if (row + 1 < height && coefficentsMagnitude[index + width] !== 0) {
|
|
sign1 = coefficentsSign[index + width];
|
|
if (significance1) {
|
|
sign0 = coefficentsSign[index - width];
|
|
contribution = 1 - sign1 - sign0 + horizontalContribution;
|
|
} else {
|
|
contribution = 1 - sign1 - sign1 + horizontalContribution;
|
|
}
|
|
} else if (significance1) {
|
|
sign0 = coefficentsSign[index - width];
|
|
contribution = 1 - sign0 - sign0 + horizontalContribution;
|
|
} else {
|
|
contribution = horizontalContribution;
|
|
}
|
|
|
|
if (contribution >= 0) {
|
|
contextLabel = 9 + contribution;
|
|
decoded = this.decoder.readBit(this.contexts, contextLabel);
|
|
} else {
|
|
contextLabel = 9 - contribution;
|
|
decoded = this.decoder.readBit(this.contexts, contextLabel) ^ 1;
|
|
}
|
|
return decoded;
|
|
},
|
|
runMagnitudeRefinementPass:
|
|
function BitModel_runMagnitudeRefinementPass() {
|
|
var decoder = this.decoder;
|
|
var width = this.width, height = this.height;
|
|
var coefficentsMagnitude = this.coefficentsMagnitude;
|
|
var neighborsSignificance = this.neighborsSignificance;
|
|
var contexts = this.contexts;
|
|
var bitsDecoded = this.bitsDecoded;
|
|
var processingFlags = this.processingFlags;
|
|
var processedMask = 1;
|
|
var firstMagnitudeBitMask = 2;
|
|
var length = width * height;
|
|
var width4 = width * 4;
|
|
|
|
for (var index0 = 0, indexNext; index0 < length; index0 = indexNext) {
|
|
indexNext = Math.min(length, index0 + width4);
|
|
for (var j = 0; j < width; j++) {
|
|
for (var index = index0 + j; index < indexNext; index += width) {
|
|
|
|
// significant but not those that have just become
|
|
if (!coefficentsMagnitude[index] ||
|
|
(processingFlags[index] & processedMask) !== 0) {
|
|
continue;
|
|
}
|
|
|
|
var contextLabel = 16;
|
|
if ((processingFlags[index] & firstMagnitudeBitMask) !== 0) {
|
|
processingFlags[index] ^= firstMagnitudeBitMask;
|
|
// first refinement
|
|
var significance = neighborsSignificance[index] & 127;
|
|
contextLabel = significance === 0 ? 15 : 14;
|
|
}
|
|
|
|
var bit = decoder.readBit(contexts, contextLabel);
|
|
coefficentsMagnitude[index] =
|
|
(coefficentsMagnitude[index] << 1) | bit;
|
|
bitsDecoded[index]++;
|
|
processingFlags[index] |= processedMask;
|
|
}
|
|
}
|
|
}
|
|
},
|
|
runCleanupPass: function BitModel_runCleanupPass() {
|
|
var decoder = this.decoder;
|
|
var width = this.width, height = this.height;
|
|
var neighborsSignificance = this.neighborsSignificance;
|
|
var coefficentsMagnitude = this.coefficentsMagnitude;
|
|
var coefficentsSign = this.coefficentsSign;
|
|
var contexts = this.contexts;
|
|
var labels = this.contextLabelTable;
|
|
var bitsDecoded = this.bitsDecoded;
|
|
var processingFlags = this.processingFlags;
|
|
var processedMask = 1;
|
|
var firstMagnitudeBitMask = 2;
|
|
var oneRowDown = width;
|
|
var twoRowsDown = width * 2;
|
|
var threeRowsDown = width * 3;
|
|
var iNext;
|
|
for (var i0 = 0; i0 < height; i0 = iNext) {
|
|
iNext = Math.min(i0 + 4, height);
|
|
var indexBase = i0 * width;
|
|
var checkAllEmpty = i0 + 3 < height;
|
|
for (var j = 0; j < width; j++) {
|
|
var index0 = indexBase + j;
|
|
// using the property: labels[neighborsSignificance[index]] == 0
|
|
// when neighborsSignificance[index] == 0
|
|
var allEmpty = (checkAllEmpty &&
|
|
processingFlags[index0] === 0 &&
|
|
processingFlags[index0 + oneRowDown] === 0 &&
|
|
processingFlags[index0 + twoRowsDown] === 0 &&
|
|
processingFlags[index0 + threeRowsDown] === 0 &&
|
|
neighborsSignificance[index0] === 0 &&
|
|
neighborsSignificance[index0 + oneRowDown] === 0 &&
|
|
neighborsSignificance[index0 + twoRowsDown] === 0 &&
|
|
neighborsSignificance[index0 + threeRowsDown] === 0);
|
|
var i1 = 0, index = index0;
|
|
var i = i0, sign;
|
|
if (allEmpty) {
|
|
var hasSignificantCoefficent =
|
|
decoder.readBit(contexts, RUNLENGTH_CONTEXT);
|
|
if (!hasSignificantCoefficent) {
|
|
bitsDecoded[index0]++;
|
|
bitsDecoded[index0 + oneRowDown]++;
|
|
bitsDecoded[index0 + twoRowsDown]++;
|
|
bitsDecoded[index0 + threeRowsDown]++;
|
|
continue; // next column
|
|
}
|
|
i1 = (decoder.readBit(contexts, UNIFORM_CONTEXT) << 1) |
|
|
decoder.readBit(contexts, UNIFORM_CONTEXT);
|
|
if (i1 !== 0) {
|
|
i = i0 + i1;
|
|
index += i1 * width;
|
|
}
|
|
|
|
sign = this.decodeSignBit(i, j, index);
|
|
coefficentsSign[index] = sign;
|
|
coefficentsMagnitude[index] = 1;
|
|
this.setNeighborsSignificance(i, j, index);
|
|
processingFlags[index] |= firstMagnitudeBitMask;
|
|
|
|
index = index0;
|
|
for (var i2 = i0; i2 <= i; i2++, index += width) {
|
|
bitsDecoded[index]++;
|
|
}
|
|
|
|
i1++;
|
|
}
|
|
for (i = i0 + i1; i < iNext; i++, index += width) {
|
|
if (coefficentsMagnitude[index] ||
|
|
(processingFlags[index] & processedMask) !== 0) {
|
|
continue;
|
|
}
|
|
|
|
var contextLabel = labels[neighborsSignificance[index]];
|
|
var decision = decoder.readBit(contexts, contextLabel);
|
|
if (decision === 1) {
|
|
sign = this.decodeSignBit(i, j, index);
|
|
coefficentsSign[index] = sign;
|
|
coefficentsMagnitude[index] = 1;
|
|
this.setNeighborsSignificance(i, j, index);
|
|
processingFlags[index] |= firstMagnitudeBitMask;
|
|
}
|
|
bitsDecoded[index]++;
|
|
}
|
|
}
|
|
}
|
|
},
|
|
checkSegmentationSymbol: function BitModel_checkSegmentationSymbol() {
|
|
var decoder = this.decoder;
|
|
var contexts = this.contexts;
|
|
var symbol = (decoder.readBit(contexts, UNIFORM_CONTEXT) << 3) |
|
|
(decoder.readBit(contexts, UNIFORM_CONTEXT) << 2) |
|
|
(decoder.readBit(contexts, UNIFORM_CONTEXT) << 1) |
|
|
decoder.readBit(contexts, UNIFORM_CONTEXT);
|
|
if (symbol != 0xA) {
|
|
throw 'Invalid segmentation symbol';
|
|
}
|
|
}
|
|
};
|
|
|
|
return BitModel;
|
|
})();
|
|
|
|
// Section F, Discrete wavelet transformation
|
|
var Transform = (function TransformClosure() {
|
|
function Transform() {}
|
|
|
|
Transform.prototype.calculate =
|
|
function transformCalculate(subbands, u0, v0) {
|
|
var ll = subbands[0];
|
|
for (var i = 1, ii = subbands.length; i < ii; i++) {
|
|
ll = this.iterate(ll, subbands[i], u0, v0);
|
|
}
|
|
return ll;
|
|
};
|
|
Transform.prototype.extend = function extend(buffer, offset, size) {
|
|
// Section F.3.7 extending... using max extension of 4
|
|
var i1 = offset - 1, j1 = offset + 1;
|
|
var i2 = offset + size - 2, j2 = offset + size;
|
|
buffer[i1--] = buffer[j1++];
|
|
buffer[j2++] = buffer[i2--];
|
|
buffer[i1--] = buffer[j1++];
|
|
buffer[j2++] = buffer[i2--];
|
|
buffer[i1--] = buffer[j1++];
|
|
buffer[j2++] = buffer[i2--];
|
|
buffer[i1] = buffer[j1];
|
|
buffer[j2] = buffer[i2];
|
|
};
|
|
Transform.prototype.iterate = function Transform_iterate(ll, hl_lh_hh,
|
|
u0, v0) {
|
|
var llWidth = ll.width, llHeight = ll.height, llItems = ll.items;
|
|
var width = hl_lh_hh.width;
|
|
var height = hl_lh_hh.height;
|
|
var items = hl_lh_hh.items;
|
|
var i, j, k, l, u, v;
|
|
|
|
// Interleave LL according to Section F.3.3
|
|
for (k = 0, i = 0; i < llHeight; i++) {
|
|
l = i * 2 * width;
|
|
for (j = 0; j < llWidth; j++, k++, l += 2) {
|
|
items[l] = llItems[k];
|
|
}
|
|
}
|
|
// The LL band is not needed anymore.
|
|
llItems = ll.items = null;
|
|
|
|
var bufferPadding = 4;
|
|
var rowBuffer = new Float32Array(width + 2 * bufferPadding);
|
|
|
|
// Section F.3.4 HOR_SR
|
|
if (width === 1) {
|
|
// if width = 1, when u0 even keep items as is, when odd divide by 2
|
|
if ((u0 & 1) !== 0) {
|
|
for (v = 0, k = 0; v < height; v++, k += width) {
|
|
items[k] *= 0.5;
|
|
}
|
|
}
|
|
} else {
|
|
for (v = 0, k = 0; v < height; v++, k += width) {
|
|
rowBuffer.set(items.subarray(k, k + width), bufferPadding);
|
|
|
|
this.extend(rowBuffer, bufferPadding, width);
|
|
this.filter(rowBuffer, bufferPadding, width);
|
|
|
|
items.set(
|
|
rowBuffer.subarray(bufferPadding, bufferPadding + width),
|
|
k);
|
|
}
|
|
}
|
|
|
|
// Accesses to the items array can take long, because it may not fit into
|
|
// CPU cache and has to be fetched from main memory. Since subsequent
|
|
// accesses to the items array are not local when reading columns, we
|
|
// have a cache miss every time. To reduce cache misses, get up to
|
|
// 'numBuffers' items at a time and store them into the individual
|
|
// buffers. The colBuffers should be small enough to fit into CPU cache.
|
|
var numBuffers = 16;
|
|
var colBuffers = [];
|
|
for (i = 0; i < numBuffers; i++) {
|
|
colBuffers.push(new Float32Array(height + 2 * bufferPadding));
|
|
}
|
|
var b, currentBuffer = 0;
|
|
ll = bufferPadding + height;
|
|
|
|
// Section F.3.5 VER_SR
|
|
if (height === 1) {
|
|
// if height = 1, when v0 even keep items as is, when odd divide by 2
|
|
if ((v0 & 1) !== 0) {
|
|
for (u = 0; u < width; u++) {
|
|
items[u] *= 0.5;
|
|
}
|
|
}
|
|
} else {
|
|
for (u = 0; u < width; u++) {
|
|
// if we ran out of buffers, copy several image columns at once
|
|
if (currentBuffer === 0) {
|
|
numBuffers = Math.min(width - u, numBuffers);
|
|
for (k = u, l = bufferPadding; l < ll; k += width, l++) {
|
|
for (b = 0; b < numBuffers; b++) {
|
|
colBuffers[b][l] = items[k + b];
|
|
}
|
|
}
|
|
currentBuffer = numBuffers;
|
|
}
|
|
|
|
currentBuffer--;
|
|
var buffer = colBuffers[currentBuffer];
|
|
this.extend(buffer, bufferPadding, height);
|
|
this.filter(buffer, bufferPadding, height);
|
|
|
|
// If this is last buffer in this group of buffers, flush all buffers.
|
|
if (currentBuffer === 0) {
|
|
k = u - numBuffers + 1;
|
|
for (l = bufferPadding; l < ll; k += width, l++) {
|
|
for (b = 0; b < numBuffers; b++) {
|
|
items[k + b] = colBuffers[b][l];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return {
|
|
width: width,
|
|
height: height,
|
|
items: items
|
|
};
|
|
};
|
|
return Transform;
|
|
})();
|
|
|
|
// Section 3.8.2 Irreversible 9-7 filter
|
|
var IrreversibleTransform = (function IrreversibleTransformClosure() {
|
|
function IrreversibleTransform() {
|
|
Transform.call(this);
|
|
}
|
|
|
|
IrreversibleTransform.prototype = Object.create(Transform.prototype);
|
|
IrreversibleTransform.prototype.filter =
|
|
function irreversibleTransformFilter(x, offset, length) {
|
|
var len = length >> 1;
|
|
offset = offset | 0;
|
|
var j, n, current, next;
|
|
|
|
var alpha = -1.586134342059924;
|
|
var beta = -0.052980118572961;
|
|
var gamma = 0.882911075530934;
|
|
var delta = 0.443506852043971;
|
|
var K = 1.230174104914001;
|
|
var K_ = 1 / K;
|
|
|
|
// step 1 is combined with step 3
|
|
|
|
// step 2
|
|
j = offset - 3;
|
|
for (n = len + 4; n--; j += 2) {
|
|
x[j] *= K_;
|
|
}
|
|
|
|
// step 1 & 3
|
|
j = offset - 2;
|
|
current = delta * x[j -1];
|
|
for (n = len + 3; n--; j += 2) {
|
|
next = delta * x[j + 1];
|
|
x[j] = K * x[j] - current - next;
|
|
if (n--) {
|
|
j += 2;
|
|
current = delta * x[j + 1];
|
|
x[j] = K * x[j] - current - next;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// step 4
|
|
j = offset - 1;
|
|
current = gamma * x[j - 1];
|
|
for (n = len + 2; n--; j += 2) {
|
|
next = gamma * x[j + 1];
|
|
x[j] -= current + next;
|
|
if (n--) {
|
|
j += 2;
|
|
current = gamma * x[j + 1];
|
|
x[j] -= current + next;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// step 5
|
|
j = offset;
|
|
current = beta * x[j - 1];
|
|
for (n = len + 1; n--; j += 2) {
|
|
next = beta * x[j + 1];
|
|
x[j] -= current + next;
|
|
if (n--) {
|
|
j += 2;
|
|
current = beta * x[j + 1];
|
|
x[j] -= current + next;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// step 6
|
|
if (len !== 0) {
|
|
j = offset + 1;
|
|
current = alpha * x[j - 1];
|
|
for (n = len; n--; j += 2) {
|
|
next = alpha * x[j + 1];
|
|
x[j] -= current + next;
|
|
if (n--) {
|
|
j += 2;
|
|
current = alpha * x[j + 1];
|
|
x[j] -= current + next;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
return IrreversibleTransform;
|
|
})();
|
|
|
|
// Section 3.8.1 Reversible 5-3 filter
|
|
var ReversibleTransform = (function ReversibleTransformClosure() {
|
|
function ReversibleTransform() {
|
|
Transform.call(this);
|
|
}
|
|
|
|
ReversibleTransform.prototype = Object.create(Transform.prototype);
|
|
ReversibleTransform.prototype.filter =
|
|
function reversibleTransformFilter(x, offset, length) {
|
|
var len = length >> 1;
|
|
offset = offset | 0;
|
|
var j, n;
|
|
|
|
for (j = offset, n = len + 1; n--; j += 2) {
|
|
x[j] -= (x[j - 1] + x[j + 1] + 2) >> 2;
|
|
}
|
|
|
|
for (j = offset + 1, n = len; n--; j += 2) {
|
|
x[j] += (x[j - 1] + x[j + 1]) >> 1;
|
|
}
|
|
};
|
|
|
|
return ReversibleTransform;
|
|
})();
|
|
|
|
return JpxImage;
|
|
})();
|
|
|