CocoRoboDesktop/img/FlashSource/upload/JPGEncoder.as

/*
  Copyright (c) 2008, Adobe Systems Incorporated
  All rights reserved.

  Redistribution and use in source and binary forms, with or without 
  modification, are permitted provided that the following conditions are
  met:

  * Redistributions of source code must retain the above copyright notice, 
    this list of conditions and the following disclaimer.
  
  * Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the 
    documentation and/or other materials provided with the distribution.
  
  * Neither the name of Adobe Systems Incorporated nor the names of its 
    contributors may be used to endorse or promote products derived from 
    this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package
{
        import flash.geom.*;
        import flash.display.*;
        import flash.utils.*;
        
        /**
         * Class that converts BitmapData into a valid JPEG
         */             
        public class JPGEncoder
        {

                // Static table initialization
        
                private var ZigZag:Array = [
                         0, 1, 5, 6,14,15,27,28,
                         2, 4, 7,13,16,26,29,42,
                         3, 8,12,17,25,30,41,43,
                         9,11,18,24,31,40,44,53,
                        10,19,23,32,39,45,52,54,
                        20,22,33,38,46,51,55,60,
                        21,34,37,47,50,56,59,61,
                        35,36,48,49,57,58,62,63
                ];
        
                private var YTable:Array = new Array(64);
                private var UVTable:Array = new Array(64);
                private var fdtbl_Y:Array = new Array(64);
                private var fdtbl_UV:Array = new Array(64);
        
                private function initQuantTables(sf:int):void
                {
                        var i:int;
                        var t:Number;
                        var YQT:Array = [
                                16, 11, 10, 16, 24, 40, 51, 61,
                                12, 12, 14, 19, 26, 58, 60, 55,
                                14, 13, 16, 24, 40, 57, 69, 56,
                                14, 17, 22, 29, 51, 87, 80, 62,
                                18, 22, 37, 56, 68,109,103, 77,
                                24, 35, 55, 64, 81,104,113, 92,
                                49, 64, 78, 87,103,121,120,101,
                                72, 92, 95, 98,112,100,103, 99
                        ];
                        for (i = 0; i < 64; i++) {
                                t = Math.floor((YQT[i]*sf+50)/100);
                                if (t < 1) {
                                        t = 1;
                                } else if (t > 255) {
                                        t = 255;
                                }
                                YTable[ZigZag[i]] = t;
                        }
                        var UVQT:Array = [
                                17, 18, 24, 47, 99, 99, 99, 99,
                                18, 21, 26, 66, 99, 99, 99, 99,
                                24, 26, 56, 99, 99, 99, 99, 99,
                                47, 66, 99, 99, 99, 99, 99, 99,
                                99, 99, 99, 99, 99, 99, 99, 99,
                                99, 99, 99, 99, 99, 99, 99, 99,
                                99, 99, 99, 99, 99, 99, 99, 99,
                                99, 99, 99, 99, 99, 99, 99, 99
                        ];
                        for (i = 0; i < 64; i++) {
                                t = Math.floor((UVQT[i]*sf+50)/100);
                                if (t < 1) {
                                        t = 1;
                                } else if (t > 255) {
                                        t = 255;
                                }
                                UVTable[ZigZag[i]] = t;
                        }
                        var aasf:Array = [
                                1.0, 1.387039845, 1.306562965, 1.175875602,
                                1.0, 0.785694958, 0.541196100, 0.275899379
                        ];
                        i = 0;
                        for (var row:int = 0; row < 8; row++)
                        {
                                for (var col:int = 0; col < 8; col++)
                                {
                                        fdtbl_Y[i]  = (1.0 / (YTable [ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
                                        fdtbl_UV[i] = (1.0 / (UVTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
                                        i++;
                                }
                        }
                }
        
                private var YDC_HT:Array;
                private var UVDC_HT:Array;
                private var YAC_HT:Array;
                private var UVAC_HT:Array;
        
                private function computeHuffmanTbl(nrcodes:Array, std_table:Array):Array
                {
                        var codevalue:int = 0;
                        var pos_in_table:int = 0;
                        var HT:Array = new Array();
                        for (var k:int=1; k<=16; k++) {
                                for (var j:int=1; j<=nrcodes[k]; j++) {
                                        HT[std_table[pos_in_table]] = new BitString();
                                        HT[std_table[pos_in_table]].val = codevalue;
                                        HT[std_table[pos_in_table]].len = k;
                                        pos_in_table++;
                                        codevalue++;
                                }
                                codevalue*=2;
                        }
                        return HT;
                }
        
                private var std_dc_luminance_nrcodes:Array = [0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0];
                private var std_dc_luminance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
                private var std_ac_luminance_nrcodes:Array = [0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d];
                private var std_ac_luminance_values:Array = [
                        0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,
                        0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,
                        0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08,
                        0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0,
                        0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16,
                        0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28,
                        0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39,
                        0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,
                        0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,
                        0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,
                        0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,
                        0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
                        0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,
                        0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,
                        0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,
                        0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,
                        0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,
                        0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2,
                        0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,
                        0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
                        0xf9,0xfa
                ];
        
                private var std_dc_chrominance_nrcodes:Array = [0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0];
                private var std_dc_chrominance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11];
                private var std_ac_chrominance_nrcodes:Array = [0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77];
                private var std_ac_chrominance_values:Array = [
                        0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,
                        0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,
                        0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,
                        0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0,
                        0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34,
                        0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26,
                        0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38,
                        0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,
                        0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,
                        0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,
                        0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,
                        0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87,
                        0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96,
                        0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,
                        0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,
                        0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,
                        0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,
                        0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,
                        0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,
                        0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
                        0xf9,0xfa
                ];
        
                private function initHuffmanTbl():void
                {
                        YDC_HT = computeHuffmanTbl(std_dc_luminance_nrcodes,std_dc_luminance_values);
                        UVDC_HT = computeHuffmanTbl(std_dc_chrominance_nrcodes,std_dc_chrominance_values);
                        YAC_HT = computeHuffmanTbl(std_ac_luminance_nrcodes,std_ac_luminance_values);
                        UVAC_HT = computeHuffmanTbl(std_ac_chrominance_nrcodes,std_ac_chrominance_values);
                }
        
                private var bitcode:Array = new Array(65535);
                private var category:Array = new Array(65535);
        
                private function initCategoryNumber():void
                {
                        var nrlower:int = 1;
                        var nrupper:int = 2;
                        var nr:int;
                        for (var cat:int=1; cat<=15; cat++) {
                                //Positive numbers
                                for (nr=nrlower; nr<nrupper; nr++) {
                                        category[32767+nr] = cat;
                                        bitcode[32767+nr] = new BitString();
                                        bitcode[32767+nr].len = cat;
                                        bitcode[32767+nr].val = nr;
                                }
                                //Negative numbers
                                for (nr=-(nrupper-1); nr<=-nrlower; nr++) {
                                        category[32767+nr] = cat;
                                        bitcode[32767+nr] = new BitString();
                                        bitcode[32767+nr].len = cat;
                                        bitcode[32767+nr].val = nrupper-1+nr;
                                }
                                nrlower <<= 1;
                                nrupper <<= 1;
                        }
                }
        
                // IO functions
        
                private var byteout:ByteArray;
                private var bytenew:int = 0;
                private var bytepos:int = 7;
        
                private function writeBits(bs:BitString):void
                {
                        var value:int = bs.val;
                        var posval:int = bs.len-1;
                        while ( posval >= 0 ) {
                                if (value & uint(1 << posval) ) {
                                        bytenew |= uint(1 << bytepos);
                                }
                                posval--;
                                bytepos--;
                                if (bytepos < 0) {
                                        if (bytenew == 0xFF) {
                                                writeByte(0xFF);
                                                writeByte(0);
                                        }
                                        else {
                                                writeByte(bytenew);
                                        }
                                        bytepos=7;
                                        bytenew=0;
                                }
                        }
                }
        
                private function writeByte(value:int):void
                {
                        byteout.writeByte(value);
                }
        
                private function writeWord(value:int):void
                {
                        writeByte((value>>8)&0xFF);
                        writeByte((value   )&0xFF);
                }
        
                // DCT & quantization core
        
                private function fDCTQuant(data:Array, fdtbl:Array):Array
                {
                        var tmp0:Number, tmp1:Number, tmp2:Number, tmp3:Number, tmp4:Number, tmp5:Number, tmp6:Number, tmp7:Number;
                        var tmp10:Number, tmp11:Number, tmp12:Number, tmp13:Number;
                        var z1:Number, z2:Number, z3:Number, z4:Number, z5:Number, z11:Number, z13:Number;
                        var i:int;
                        /* Pass 1: process rows. */
                        var dataOff:int=0;
                        for (i=0; i<8; i++) {
                                tmp0 = data[dataOff+0] + data[dataOff+7];
                                tmp7 = data[dataOff+0] - data[dataOff+7];
                                tmp1 = data[dataOff+1] + data[dataOff+6];
                                tmp6 = data[dataOff+1] - data[dataOff+6];
                                tmp2 = data[dataOff+2] + data[dataOff+5];
                                tmp5 = data[dataOff+2] - data[dataOff+5];
                                tmp3 = data[dataOff+3] + data[dataOff+4];
                                tmp4 = data[dataOff+3] - data[dataOff+4];
        
                                /* Even part */
                                tmp10 = tmp0 + tmp3;    /* phase 2 */
                                tmp13 = tmp0 - tmp3;
                                tmp11 = tmp1 + tmp2;
                                tmp12 = tmp1 - tmp2;
        
                                data[dataOff+0] = tmp10 + tmp11; /* phase 3 */
                                data[dataOff+4] = tmp10 - tmp11;
        
                                z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
                                data[dataOff+2] = tmp13 + z1; /* phase 5 */
                                data[dataOff+6] = tmp13 - z1;
        
                                /* Odd part */
                                tmp10 = tmp4 + tmp5; /* phase 2 */
                                tmp11 = tmp5 + tmp6;
                                tmp12 = tmp6 + tmp7;
        
                                /* The rotator is modified from fig 4-8 to avoid extra negations. */
                                z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
                                z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
                                z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
                                z3 = tmp11 * 0.707106781; /* c4 */
        
                                z11 = tmp7 + z3;        /* phase 5 */
                                z13 = tmp7 - z3;
        
                                data[dataOff+5] = z13 + z2;     /* phase 6 */
                                data[dataOff+3] = z13 - z2;
                                data[dataOff+1] = z11 + z4;
                                data[dataOff+7] = z11 - z4;
        
                                dataOff += 8; /* advance pointer to next row */
                        }
        
                        /* Pass 2: process columns. */
                        dataOff = 0;
                        for (i=0; i<8; i++) {
                                tmp0 = data[dataOff+ 0] + data[dataOff+56];
                                tmp7 = data[dataOff+ 0] - data[dataOff+56];
                                tmp1 = data[dataOff+ 8] + data[dataOff+48];
                                tmp6 = data[dataOff+ 8] - data[dataOff+48];
                                tmp2 = data[dataOff+16] + data[dataOff+40];
                                tmp5 = data[dataOff+16] - data[dataOff+40];
                                tmp3 = data[dataOff+24] + data[dataOff+32];
                                tmp4 = data[dataOff+24] - data[dataOff+32];
        
                                /* Even part */
                                tmp10 = tmp0 + tmp3;    /* phase 2 */
                                tmp13 = tmp0 - tmp3;
                                tmp11 = tmp1 + tmp2;
                                tmp12 = tmp1 - tmp2;
        
                                data[dataOff+ 0] = tmp10 + tmp11; /* phase 3 */
                                data[dataOff+32] = tmp10 - tmp11;
        
                                z1 = (tmp12 + tmp13) * 0.707106781; /* c4 */
                                data[dataOff+16] = tmp13 + z1; /* phase 5 */
                                data[dataOff+48] = tmp13 - z1;
        
                                /* Odd part */
                                tmp10 = tmp4 + tmp5; /* phase 2 */
                                tmp11 = tmp5 + tmp6;
                                tmp12 = tmp6 + tmp7;
        
                                /* The rotator is modified from fig 4-8 to avoid extra negations. */
                                z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
                                z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
                                z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
                                z3 = tmp11 * 0.707106781; /* c4 */
        
                                z11 = tmp7 + z3;        /* phase 5 */
                                z13 = tmp7 - z3;
        
                                data[dataOff+40] = z13 + z2; /* phase 6 */
                                data[dataOff+24] = z13 - z2;
                                data[dataOff+ 8] = z11 + z4;
                                data[dataOff+56] = z11 - z4;
        
                                dataOff++; /* advance pointer to next column */
                        }
        
                        // Quantize/descale the coefficients
                        for (i=0; i<64; i++) {
                                // Apply the quantization and scaling factor & Round to nearest integer
                                data[i] = Math.round((data[i]*fdtbl[i]));
                        }
                        return data;
                }
        
                // Chunk writing
        
                private function writeAPP0():void
                {
                        writeWord(0xFFE0); // marker
                        writeWord(16); // length
                        writeByte(0x4A); // J
                        writeByte(0x46); // F
                        writeByte(0x49); // I
                        writeByte(0x46); // F
                        writeByte(0); // = "JFIF",'\0'
                        writeByte(1); // versionhi
                        writeByte(1); // versionlo
                        writeByte(0); // xyunits
                        writeWord(1); // xdensity
                        writeWord(1); // ydensity
                        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;
                }
        }
}