652 lines
18 KiB
ActionScript
652 lines
18 KiB
ActionScript
/*
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Adobe Systems Incorporated(r) Source Code License Agreement
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Copyright(c) 2005 Adobe Systems Incorporated. All rights reserved.
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Please read this Source Code License Agreement carefully before using
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the source code.
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Adobe Systems Incorporated grants to you a perpetual, worldwide, non-exclusive,
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no-charge, royalty-free, irrevocable copyright license, to reproduce,
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prepare derivative works of, publicly display, publicly perform, and
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distribute this source code and such derivative works in source or
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object code form without any attribution requirements.
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The name "Adobe Systems Incorporated" must not be used to endorse or promote products
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derived from the source code without prior written permission.
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You agree to indemnify, hold harmless and defend Adobe Systems Incorporated from and
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against any loss, damage, claims or lawsuits, including attorney's
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fees that arise or result from your use or distribution of the source
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code.
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THIS SOURCE CODE IS PROVIDED "AS IS" AND "WITH ALL FAULTS", WITHOUT
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ANY TECHNICAL SUPPORT OR ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE ARE DISCLAIMED. ALSO, THERE IS NO WARRANTY OF
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NON-INFRINGEMENT, TITLE OR QUIET ENJOYMENT. IN NO EVENT SHALL MACROMEDIA
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OR ITS SUPPLIERS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOURCE CODE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package com.adobe.images
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{
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import flash.geom.*;
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import flash.display.*;
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import flash.utils.*;
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/**
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* Class that converts BitmapData into a valid JPEG
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*/
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public class JPGEncoder
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{
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// Static table initialization
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private var ZigZag:Array = [
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0, 1, 5, 6,14,15,27,28,
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2, 4, 7,13,16,26,29,42,
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3, 8,12,17,25,30,41,43,
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9,11,18,24,31,40,44,53,
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10,19,23,32,39,45,52,54,
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20,22,33,38,46,51,55,60,
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21,34,37,47,50,56,59,61,
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35,36,48,49,57,58,62,63
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];
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private var YTable:Array = new Array(64);
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private var UVTable:Array = new Array(64);
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private var fdtbl_Y:Array = new Array(64);
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private var fdtbl_UV:Array = new Array(64);
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private function initQuantTables(sf:int):void
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{
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var i:int;
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var t:Number;
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var YQT:Array = [
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16, 11, 10, 16, 24, 40, 51, 61,
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12, 12, 14, 19, 26, 58, 60, 55,
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14, 13, 16, 24, 40, 57, 69, 56,
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14, 17, 22, 29, 51, 87, 80, 62,
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18, 22, 37, 56, 68,109,103, 77,
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24, 35, 55, 64, 81,104,113, 92,
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49, 64, 78, 87,103,121,120,101,
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72, 92, 95, 98,112,100,103, 99
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];
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for (i = 0; i < 64; i++) {
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t = Math.floor((YQT[i]*sf+50)/100);
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if (t < 1) {
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t = 1;
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} else if (t > 255) {
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t = 255;
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}
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YTable[ZigZag[i]] = t;
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}
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var UVQT:Array = [
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17, 18, 24, 47, 99, 99, 99, 99,
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18, 21, 26, 66, 99, 99, 99, 99,
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24, 26, 56, 99, 99, 99, 99, 99,
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47, 66, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99
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];
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for (i = 0; i < 64; i++) {
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t = Math.floor((UVQT[i]*sf+50)/100);
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if (t < 1) {
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t = 1;
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} else if (t > 255) {
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t = 255;
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}
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UVTable[ZigZag[i]] = t;
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}
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var aasf:Array = [
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1.0, 1.387039845, 1.306562965, 1.175875602,
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1.0, 0.785694958, 0.541196100, 0.275899379
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];
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i = 0;
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for (var row:int = 0; row < 8; row++)
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{
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for (var col:int = 0; col < 8; col++)
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{
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fdtbl_Y[i] = (1.0 / (YTable [ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
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fdtbl_UV[i] = (1.0 / (UVTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
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i++;
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}
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}
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}
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private var YDC_HT:Array;
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private var UVDC_HT:Array;
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private var YAC_HT:Array;
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private var UVAC_HT:Array;
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private function computeHuffmanTbl(nrcodes:Array, std_table:Array):Array
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{
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var codevalue:int = 0;
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var pos_in_table:int = 0;
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var HT:Array = new Array();
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for (var k:int=1; k<=16; k++) {
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for (var j:int=1; j<=nrcodes[k]; j++) {
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HT[std_table[pos_in_table]] = new BitString();
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HT[std_table[pos_in_table]].val = codevalue;
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HT[std_table[pos_in_table]].len = k;
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pos_in_table++;
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codevalue++;
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}
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codevalue*=2;
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}
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return HT;
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}
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private var std_dc_luminance_nrcodes:Array = [0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0];
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private var std_dc_luminance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
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private var std_ac_luminance_nrcodes:Array = [0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d];
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private var std_ac_luminance_values:Array = [
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0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,
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0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,
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0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08,
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0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0,
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0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16,
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0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28,
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0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39,
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0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,
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0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,
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0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,
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0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,
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0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
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0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,
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0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,
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0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,
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0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,
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0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,
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0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2,
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0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,
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0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
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0xf9,0xfa
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];
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private var std_dc_chrominance_nrcodes:Array = [0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0];
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private var std_dc_chrominance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
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private var std_ac_chrominance_nrcodes:Array = [0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77];
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private var std_ac_chrominance_values:Array = [
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0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,
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0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,
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0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,
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0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0,
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0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34,
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0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26,
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0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38,
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0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,
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0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,
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0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,
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0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,
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0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87,
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0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96,
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0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,
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0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,
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0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,
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0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,
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0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,
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0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,
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0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
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0xf9,0xfa
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];
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private function initHuffmanTbl():void
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{
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YDC_HT = computeHuffmanTbl(std_dc_luminance_nrcodes,std_dc_luminance_values);
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UVDC_HT = computeHuffmanTbl(std_dc_chrominance_nrcodes,std_dc_chrominance_values);
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YAC_HT = computeHuffmanTbl(std_ac_luminance_nrcodes,std_ac_luminance_values);
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UVAC_HT = computeHuffmanTbl(std_ac_chrominance_nrcodes,std_ac_chrominance_values);
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}
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private var bitcode:Array = new Array(65535);
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private var category:Array = new Array(65535);
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private function initCategoryNumber():void
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{
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var nrlower:int = 1;
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var nrupper:int = 2;
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var nr:int;
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for (var cat:int=1; cat<=15; cat++) {
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//Positive numbers
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for (nr=nrlower; nr<nrupper; nr++) {
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category[32767+nr] = cat;
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bitcode[32767+nr] = new BitString();
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bitcode[32767+nr].len = cat;
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bitcode[32767+nr].val = nr;
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}
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//Negative numbers
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for (nr=-(nrupper-1); nr<=-nrlower; nr++) {
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category[32767+nr] = cat;
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bitcode[32767+nr] = new BitString();
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bitcode[32767+nr].len = cat;
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bitcode[32767+nr].val = nrupper-1+nr;
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}
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nrlower <<= 1;
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nrupper <<= 1;
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}
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}
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// IO functions
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private var byteout:ByteArray;
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private var bytenew:int = 0;
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private var bytepos:int = 7;
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private function writeBits(bs:BitString):void
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{
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var value:int = bs.val;
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var posval:int = bs.len-1;
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while ( posval >= 0 ) {
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if (value & uint(1 << posval) ) {
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bytenew |= uint(1 << bytepos);
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}
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posval--;
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bytepos--;
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if (bytepos < 0) {
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if (bytenew == 0xFF) {
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writeByte(0xFF);
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writeByte(0);
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}
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else {
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writeByte(bytenew);
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}
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bytepos=7;
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bytenew=0;
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}
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}
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}
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private function writeByte(value:int):void
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{
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byteout.writeByte(value);
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}
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private function writeWord(value:int):void
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{
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writeByte((value>>8)&0xFF);
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writeByte((value )&0xFF);
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}
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// DCT & quantization core
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private function fDCTQuant(data:Array, fdtbl:Array):Array
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{
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var tmp0:Number, tmp1:Number, tmp2:Number, tmp3:Number, tmp4:Number, tmp5:Number, tmp6:Number, tmp7:Number;
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var tmp10:Number, tmp11:Number, tmp12:Number, tmp13:Number;
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var z1:Number, z2:Number, z3:Number, z4:Number, z5:Number, z11:Number, z13:Number;
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var i:int;
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/* Pass 1: process rows. */
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var dataOff:int=0;
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for (i=0; i<8; i++) {
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tmp0 = data[dataOff+0] + data[dataOff+7];
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tmp7 = data[dataOff+0] - data[dataOff+7];
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tmp1 = data[dataOff+1] + data[dataOff+6];
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tmp6 = data[dataOff+1] - data[dataOff+6];
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tmp2 = data[dataOff+2] + data[dataOff+5];
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tmp5 = data[dataOff+2] - data[dataOff+5];
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tmp3 = data[dataOff+3] + data[dataOff+4];
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tmp4 = data[dataOff+3] - data[dataOff+4];
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/* Even part */
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tmp10 = tmp0 + tmp3; /* phase 2 */
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tmp13 = tmp0 - tmp3;
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tmp11 = tmp1 + tmp2;
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tmp12 = tmp1 - tmp2;
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data[dataOff+0] = tmp10 + tmp11; /* phase 3 */
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data[dataOff+4] = tmp10 - tmp11;
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z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
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data[dataOff+2] = tmp13 + z1; /* phase 5 */
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data[dataOff+6] = tmp13 - z1;
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/* Odd part */
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tmp10 = tmp4 + tmp5; /* phase 2 */
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tmp11 = tmp5 + tmp6;
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tmp12 = tmp6 + tmp7;
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/* The rotator is modified from fig 4-8 to avoid extra negations. */
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z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
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z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
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z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
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z3 = tmp11 * 0.707106781; /* c4 */
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z11 = tmp7 + z3; /* phase 5 */
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z13 = tmp7 - z3;
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data[dataOff+5] = z13 + z2; /* phase 6 */
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data[dataOff+3] = z13 - z2;
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data[dataOff+1] = z11 + z4;
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data[dataOff+7] = z11 - z4;
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dataOff += 8; /* advance pointer to next row */
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}
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/* Pass 2: process columns. */
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dataOff = 0;
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for (i=0; i<8; i++) {
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tmp0 = data[dataOff+ 0] + data[dataOff+56];
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tmp7 = data[dataOff+ 0] - data[dataOff+56];
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tmp1 = data[dataOff+ 8] + data[dataOff+48];
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tmp6 = data[dataOff+ 8] - data[dataOff+48];
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tmp2 = data[dataOff+16] + data[dataOff+40];
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tmp5 = data[dataOff+16] - data[dataOff+40];
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tmp3 = data[dataOff+24] + data[dataOff+32];
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tmp4 = data[dataOff+24] - data[dataOff+32];
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/* Even part */
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tmp10 = tmp0 + tmp3; /* phase 2 */
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tmp13 = tmp0 - tmp3;
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tmp11 = tmp1 + tmp2;
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tmp12 = tmp1 - tmp2;
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data[dataOff+ 0] = tmp10 + tmp11; /* phase 3 */
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data[dataOff+32] = tmp10 - tmp11;
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z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
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data[dataOff+16] = tmp13 + z1; /* phase 5 */
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data[dataOff+48] = tmp13 - z1;
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/* Odd part */
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tmp10 = tmp4 + tmp5; /* phase 2 */
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tmp11 = tmp5 + tmp6;
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tmp12 = tmp6 + tmp7;
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/* The rotator is modified from fig 4-8 to avoid extra negations. */
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z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
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z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
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z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
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z3 = tmp11 * 0.707106781; /* c4 */
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z11 = tmp7 + z3; /* phase 5 */
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z13 = tmp7 - z3;
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data[dataOff+40] = z13 + z2; /* phase 6 */
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data[dataOff+24] = z13 - z2;
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data[dataOff+ 8] = z11 + z4;
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data[dataOff+56] = z11 - z4;
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dataOff++; /* advance pointer to next column */
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}
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// Quantize/descale the coefficients
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for (i=0; i<64; i++) {
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// Apply the quantization and scaling factor & Round to nearest integer
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data[i] = Math.round((data[i]*fdtbl[i]));
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}
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return data;
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}
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// Chunk writing
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private function writeAPP0():void
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{
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writeWord(0xFFE0); // marker
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writeWord(16); // length
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writeByte(0x4A); // J
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writeByte(0x46); // F
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writeByte(0x49); // I
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writeByte(0x46); // F
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writeByte(0); // = "JFIF",'\0'
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writeByte(1); // versionhi
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writeByte(1); // versionlo
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writeByte(0); // xyunits
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writeWord(1); // xdensity
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writeWord(1); // ydensity
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writeByte(0); // thumbnwidth
|
|
writeByte(0); // thumbnheight
|
|
}
|
|
|
|
private function writeSOF0(width:int, height:int):void
|
|
{
|
|
writeWord(0xFFC0); // marker
|
|
writeWord(17); // length, truecolor YUV JPG
|
|
writeByte(8); // precision
|
|
writeWord(height);
|
|
writeWord(width);
|
|
writeByte(3); // nrofcomponents
|
|
writeByte(1); // IdY
|
|
writeByte(0x11); // HVY
|
|
writeByte(0); // QTY
|
|
writeByte(2); // IdU
|
|
writeByte(0x11); // HVU
|
|
writeByte(1); // QTU
|
|
writeByte(3); // IdV
|
|
writeByte(0x11); // HVV
|
|
writeByte(1); // QTV
|
|
}
|
|
|
|
private function writeDQT():void
|
|
{
|
|
writeWord(0xFFDB); // marker
|
|
writeWord(132); // length
|
|
writeByte(0);
|
|
var i:int;
|
|
for (i=0; i<64; i++) {
|
|
writeByte(YTable[i]);
|
|
}
|
|
writeByte(1);
|
|
for (i=0; i<64; i++) {
|
|
writeByte(UVTable[i]);
|
|
}
|
|
}
|
|
|
|
private function writeDHT():void
|
|
{
|
|
writeWord(0xFFC4); // marker
|
|
writeWord(0x01A2); // length
|
|
var i:int;
|
|
|
|
writeByte(0); // HTYDCinfo
|
|
for (i=0; i<16; i++) {
|
|
writeByte(std_dc_luminance_nrcodes[i+1]);
|
|
}
|
|
for (i=0; i<=11; i++) {
|
|
writeByte(std_dc_luminance_values[i]);
|
|
}
|
|
|
|
writeByte(0x10); // HTYACinfo
|
|
for (i=0; i<16; i++) {
|
|
writeByte(std_ac_luminance_nrcodes[i+1]);
|
|
}
|
|
for (i=0; i<=161; i++) {
|
|
writeByte(std_ac_luminance_values[i]);
|
|
}
|
|
|
|
writeByte(1); // HTUDCinfo
|
|
for (i=0; i<16; i++) {
|
|
writeByte(std_dc_chrominance_nrcodes[i+1]);
|
|
}
|
|
for (i=0; i<=11; i++) {
|
|
writeByte(std_dc_chrominance_values[i]);
|
|
}
|
|
|
|
writeByte(0x11); // HTUACinfo
|
|
for (i=0; i<16; i++) {
|
|
writeByte(std_ac_chrominance_nrcodes[i+1]);
|
|
}
|
|
for (i=0; i<=161; i++) {
|
|
writeByte(std_ac_chrominance_values[i]);
|
|
}
|
|
}
|
|
|
|
private function writeSOS():void
|
|
{
|
|
writeWord(0xFFDA); // marker
|
|
writeWord(12); // length
|
|
writeByte(3); // nrofcomponents
|
|
writeByte(1); // IdY
|
|
writeByte(0); // HTY
|
|
writeByte(2); // IdU
|
|
writeByte(0x11); // HTU
|
|
writeByte(3); // IdV
|
|
writeByte(0x11); // HTV
|
|
writeByte(0); // Ss
|
|
writeByte(0x3f); // Se
|
|
writeByte(0); // Bf
|
|
}
|
|
|
|
// Core processing
|
|
private var DU:Array = new Array(64);
|
|
|
|
private function processDU(CDU:Array, fdtbl:Array, DC:Number, HTDC:Array, HTAC:Array):Number
|
|
{
|
|
var EOB:BitString = HTAC[0x00];
|
|
var M16zeroes:BitString = HTAC[0xF0];
|
|
var i:int;
|
|
|
|
var DU_DCT:Array = fDCTQuant(CDU, fdtbl);
|
|
//ZigZag reorder
|
|
for (i=0;i<64;i++) {
|
|
DU[ZigZag[i]]=DU_DCT[i];
|
|
}
|
|
var Diff:int = DU[0] - DC; DC = DU[0];
|
|
//Encode DC
|
|
if (Diff==0) {
|
|
writeBits(HTDC[0]); // Diff might be 0
|
|
} else {
|
|
writeBits(HTDC[category[32767+Diff]]);
|
|
writeBits(bitcode[32767+Diff]);
|
|
}
|
|
//Encode ACs
|
|
var end0pos:int = 63;
|
|
for (; (end0pos>0)&&(DU[end0pos]==0); end0pos--) {
|
|
};
|
|
//end0pos = first element in reverse order !=0
|
|
if ( end0pos == 0) {
|
|
writeBits(EOB);
|
|
return DC;
|
|
}
|
|
i = 1;
|
|
while ( i <= end0pos ) {
|
|
var startpos:int = i;
|
|
for (; (DU[i]==0) && (i<=end0pos); i++) {
|
|
}
|
|
var nrzeroes:int = i-startpos;
|
|
if ( nrzeroes >= 16 ) {
|
|
for (var nrmarker:int=1; nrmarker <= nrzeroes/16; nrmarker++) {
|
|
writeBits(M16zeroes);
|
|
}
|
|
nrzeroes = int(nrzeroes&0xF);
|
|
}
|
|
writeBits(HTAC[nrzeroes*16+category[32767+DU[i]]]);
|
|
writeBits(bitcode[32767+DU[i]]);
|
|
i++;
|
|
}
|
|
if ( end0pos != 63 ) {
|
|
writeBits(EOB);
|
|
}
|
|
return DC;
|
|
}
|
|
|
|
private var YDU:Array = new Array(64);
|
|
private var UDU:Array = new Array(64);
|
|
private var VDU:Array = new Array(64);
|
|
|
|
private function RGB2YUV(img:BitmapData, xpos:int, ypos:int):void
|
|
{
|
|
var pos:int=0;
|
|
for (var y:int=0; y<8; y++) {
|
|
for (var x:int=0; x<8; x++) {
|
|
var P:uint = img.getPixel32(xpos+x,ypos+y);
|
|
var R:Number = Number((P>>16)&0xFF);
|
|
var G:Number = Number((P>> 8)&0xFF);
|
|
var B:Number = Number((P )&0xFF);
|
|
YDU[pos]=((( 0.29900)*R+( 0.58700)*G+( 0.11400)*B))-128;
|
|
UDU[pos]=(((-0.16874)*R+(-0.33126)*G+( 0.50000)*B));
|
|
VDU[pos]=((( 0.50000)*R+(-0.41869)*G+(-0.08131)*B));
|
|
pos++;
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Constructor for JPEGEncoder class
|
|
*
|
|
* @param quality The quality level between 1 and 100 that detrmines the
|
|
* level of compression used in the generated JPEG
|
|
* @langversion ActionScript 3.0
|
|
* @playerversion Flash 9.0
|
|
* @tiptext
|
|
*/
|
|
public function JPGEncoder(quality:Number = 50)
|
|
{
|
|
if (quality <= 0) {
|
|
quality = 1;
|
|
}
|
|
if (quality > 100) {
|
|
quality = 100;
|
|
}
|
|
var sf:int = 0;
|
|
if (quality < 50) {
|
|
sf = int(5000 / quality);
|
|
} else {
|
|
sf = int(200 - quality*2);
|
|
}
|
|
// Create tables
|
|
initHuffmanTbl();
|
|
initCategoryNumber();
|
|
initQuantTables(sf);
|
|
}
|
|
|
|
/**
|
|
* Created a JPEG image from the specified BitmapData
|
|
*
|
|
* @param image The BitmapData that will be converted into the JPEG format.
|
|
* @return a ByteArray representing the JPEG encoded image data.
|
|
* @langversion ActionScript 3.0
|
|
* @playerversion Flash 9.0
|
|
* @tiptext
|
|
*/
|
|
public function encode(image:BitmapData):ByteArray
|
|
{
|
|
// Initialize bit writer
|
|
byteout = new ByteArray();
|
|
bytenew=0;
|
|
bytepos=7;
|
|
|
|
// Add JPEG headers
|
|
writeWord(0xFFD8); // SOI
|
|
writeAPP0();
|
|
writeDQT();
|
|
writeSOF0(image.width,image.height);
|
|
writeDHT();
|
|
writeSOS();
|
|
|
|
|
|
// Encode 8x8 macroblocks
|
|
var DCY:Number=0;
|
|
var DCU:Number=0;
|
|
var DCV:Number=0;
|
|
bytenew=0;
|
|
bytepos=7;
|
|
for (var ypos:int=0; ypos<image.height; ypos+=8) {
|
|
for (var xpos:int=0; xpos<image.width; xpos+=8) {
|
|
RGB2YUV(image, xpos, ypos);
|
|
DCY = processDU(YDU, fdtbl_Y, DCY, YDC_HT, YAC_HT);
|
|
DCU = processDU(UDU, fdtbl_UV, DCU, UVDC_HT, UVAC_HT);
|
|
DCV = processDU(VDU, fdtbl_UV, DCV, UVDC_HT, UVAC_HT);
|
|
}
|
|
}
|
|
|
|
// Do the bit alignment of the EOI marker
|
|
if ( bytepos >= 0 ) {
|
|
var fillbits:BitString = new BitString();
|
|
fillbits.len = bytepos+1;
|
|
fillbits.val = (1<<(bytepos+1))-1;
|
|
writeBits(fillbits);
|
|
}
|
|
|
|
writeWord(0xFFD9); //EOI
|
|
return byteout;
|
|
}
|
|
}
|
|
}
|