JPEGEncoder.cs

using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;

public class ByteArray {
    private MemoryStream stream;
    private BinaryWriter writer;

    public ByteArray() {
        stream = new MemoryStream();
        writer = new BinaryWriter(stream);
    }

    /**
    * Function from AS3--add a byte to our stream
    */

    public void writeByte(byte value) {
        writer.Write(value);
    }

    /**
    * Spit back all bytes--to either pass via WWW or save to disk
    */

    public byte[] GetAllBytes() {
        byte[] buffer = new byte[stream.Length];
        stream.Position = 0;
        stream.Read(buffer, 0, buffer.Length);

        return buffer;
    }
}

/**
* This should really be a struct--if you care, declare it in C#
*/

internal class BitString {
    public int len = 0;
    public int val = 0;
}

/**
* Another flash class--emulating the stuff the encoder uses
*/

public class BitmapData {
    public int height;
    public int width;

    private Color[] pixels;

    /**
    * Pull all of our pixels off the texture (Unity stuff isn't thread safe, and this is faster)
    */

    public BitmapData(Texture2D texture) {
        height = texture.height;
        width = texture.width;

        pixels = texture.GetPixels();
    }

    /**
    * Mimic the flash function
    */

    public Color getPixelColor(int x, int y) {
        if (x >= width)
            x = width - 1;

        if (y >= height)
            y = height - 1;

        if (x < 0)
            x = 0;

        if (y < 0)
            y = 0;

        return pixels[y * width + x];
    }
}

/**
 * Class that converts BitmapData into a valid JPEG
 */

public class JPGEncoder {

    // Static table initialization

    public int[] ZigZag = new int[64] {
  	 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 int[] YTable = new int[64];
    private int[] UVTable = new int[64];
    private float[] fdtbl_Y = new float[64];
    private float[] fdtbl_UV = new float[64];

    private void initQuantTables(int sf) {
        int i;
        float t;
        int[] YQT = new int[64] {
			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 = Mathf.Floor((YQT[i] * sf + 50.0f) / 100.0f);
            if (t < 1.0f) {
                t = 1.0f;
            }
            else if (t > 255.0f) {
                t = 255.0f;
            }
            YTable[ZigZag[i]] = (int)t;
        }

        int[] UVQT = new int[64] {
			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 = Mathf.Floor((UVQT[i] * sf + 50.0f) / 100.0f);
            if (t < 1.0f) {
                t = 1.0f;
            }
            else if (t > 255.0f) {
                t = 255.0f;
            }
            UVTable[ZigZag[i]] = (int)t;
        }

        float[] aasf = new float[8] {
			1.0f, 1.387039845f, 1.306562965f, 1.175875602f,
			1.0f, 0.785694958f, 0.541196100f, 0.275899379f
		};

        i = 0;
        for (int row = 0; row < 8; row++) {
            for (int col = 0; col < 8; col++) {
                fdtbl_Y[i] = (1.0f / (YTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0f));
                fdtbl_UV[i] = (1.0f / (UVTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0f));
                i++;
            }
        }
    }

    private BitString[] YDC_HT;
    private BitString[] UVDC_HT;
    private BitString[] YAC_HT;
    private BitString[] UVAC_HT;

    private BitString[] computeHuffmanTbl(int[] nrcodes, int[] std_table) {
        int codevalue = 0;
        int pos_in_table = 0;
        BitString[] HT = new BitString[16 * 16];
        for (int k = 1; k <= 16; k++) {
            for (int j = 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 int[] std_dc_luminance_nrcodes = new int[17] { 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
    private int[] std_dc_luminance_values = new int[12] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
    private int[] std_ac_luminance_nrcodes = new int[17] { 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };

    private int[] std_ac_luminance_values = new int[162] {
		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 int[] std_dc_chrominance_nrcodes = new int[17] { 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
    private int[] std_dc_chrominance_values = new int[12] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
    private int[] std_ac_chrominance_nrcodes = new int[17] { 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };

    private int[] std_ac_chrominance_values = new int[162] {
		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 void initHuffmanTbl() {
        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 BitString[] bitcode = new BitString[65535];
    private int[] category = new int[65535];

    private void initCategoryfloat() {
        int nrlower = 1;
        int nrupper = 2;
        int nr;
        BitString bs;

        for (int cat = 1; cat <= 15; cat++) {

            //Positive numbers
            for (nr = nrlower; nr < nrupper; nr++) {
                category[32767 + nr] = cat;

                bs = new BitString();
                bs.len = cat;
                bs.val = nr;
                bitcode[32767 + nr] = bs;
            }

            //Negative numbers
            for (nr = -(nrupper - 1); nr <= -nrlower; nr++) {
                category[32767 + nr] = cat;

                bs = new BitString();
                bs.len = cat;
                bs.val = nrupper - 1 + nr;
                bitcode[32767 + nr] = bs;
            }
            nrlower <<= 1;
            nrupper <<= 1;
        }
    }

    // IO functions
    private int bytenew = 0;

    private int bytepos = 7;
    public ByteArray byteout = new ByteArray();

    /**
    * Get the result
    */

    public byte[] GetBytes() {
        if (!isDone) {
            Debug.LogError("JPEGEncoder not complete, cannot get bytes!");
            return new byte[1];
        }

        return byteout.GetAllBytes();
    }

    private void writeBits(BitString bs) {
        int value = bs.val;
        int posval = bs.len - 1;
        while (posval >= 0) {
            if (((uint)value & System.Convert.ToUInt32(1 << posval)) != 0) {
                bytenew |= (int)(System.Convert.ToUInt32(1 << bytepos));
            }
            posval--;
            bytepos--;
            if (bytepos < 0) {
                if (bytenew == 0xFF) {
                    writeByte(0xFF);
                    writeByte(0);
                }
                else {
                    writeByte((byte)bytenew);
                }
                bytepos = 7;
                bytenew = 0;
            }
        }
    }

    private void writeByte(byte value) {
        byteout.writeByte(value);
    }

    private void writeWord(int value) {
        writeByte((byte)((value >> 8) & 0xFF));
        writeByte((byte)((value) & 0xFF));
    }

    // DCT & quantization core

    private float[] fDCTQuant(float[] data, float[] fdtbl) {
        float tmp0; float tmp1; float tmp2; float tmp3; float tmp4; float tmp5; float tmp6; float tmp7;
        float tmp10; float tmp11; float tmp12; float tmp13;

        float z1; float z2; float z3; float z4; float z5; float z11; float z13;

        int i;

        /* Pass 1: process rows. */
        int dataOff = 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) * 0.707106781f; /* 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) * 0.382683433f; /* c6 */
            z2 = 0.541196100f * tmp10 + z5; /* c2-c6 */
            z4 = 1.306562965f * tmp12 + z5; /* c2+c6 */
            z3 = tmp11 * 0.707106781f; /* 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) * 0.707106781f; /* 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) * 0.382683433f; /* c6 */
            z2 = 0.541196100f * tmp10 + z5; /* c2-c6 */
            z4 = 1.306562965f * tmp12 + z5; /* c2+c6 */
            z3 = tmp11 * 0.707106781f; /* 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] = Mathf.Round((data[i] * fdtbl[i]));
        }
        return data;
    }

    // Chunk writing

    private void writeAPP0() {
        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 void writeSOF0(int width, int height) {
        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 void writeDQT() {
        writeWord(0xFFDB); // marker
        writeWord(132);	   // length
        writeByte(0);
        int i;
        for (i = 0; i < 64; i++) {
            writeByte((byte)(YTable[i]));
        }
        writeByte(1);
        for (i = 0; i < 64; i++) {
            writeByte((byte)(UVTable[i]));
        }
    }

    private void writeDHT() {
        writeWord(0xFFC4); // marker
        writeWord(0x01A2); // length
        int i;

        writeByte(0); // HTYDCinfo
        for (i = 0; i < 16; i++) {
            writeByte((byte)(std_dc_luminance_nrcodes[i + 1]));
        }
        for (i = 0; i <= 11; i++) {
            writeByte((byte)(std_dc_luminance_values[i]));
        }

        writeByte(0x10); // HTYACinfo
        for (i = 0; i < 16; i++) {
            writeByte((byte)(std_ac_luminance_nrcodes[i + 1]));
        }
        for (i = 0; i <= 161; i++) {
            writeByte((byte)(std_ac_luminance_values[i]));
        }

        writeByte(1); // HTUDCinfo
        for (i = 0; i < 16; i++) {
            writeByte((byte)(std_dc_chrominance_nrcodes[i + 1]));
        }
        for (i = 0; i <= 11; i++) {
            writeByte((byte)(std_dc_chrominance_values[i]));
        }

        writeByte(0x11); // HTUACinfo
        for (i = 0; i < 16; i++) {
            writeByte((byte)(std_ac_chrominance_nrcodes[i + 1]));
        }
        for (i = 0; i <= 161; i++) {
            writeByte((byte)(std_ac_chrominance_values[i]));
        }
    }

    private void writeSOS() {
        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 int[] DU = new int[64];

    private float processDU(float[] CDU, float[] fdtbl, float DC, BitString[] HTDC, BitString[] HTAC) {
        BitString EOB = HTAC[0x00];
        BitString M16zeroes = HTAC[0xF0];
        int i;

        float[] DU_DCT = fDCTQuant(CDU, fdtbl);

        //ZigZag reorder
        for (i = 0; i < 64; i++) {
            DU[ZigZag[i]] = (int)(DU_DCT[i]);
        }
        int 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
        int end0pos = 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) {
            int startpos = i;
            for (; (DU[i] == 0) && (i <= end0pos); i++) {
            }
            int nrzeroes = i - startpos;
            if (nrzeroes >= 16) {
                for (int nrmarker = 1; nrmarker <= nrzeroes / 16; nrmarker++) {
                    writeBits(M16zeroes);
                }
                nrzeroes = (nrzeroes & 0xF);
            }
            writeBits(HTAC[nrzeroes * 16 + category[32767 + DU[i]]]);
            writeBits(bitcode[32767 + DU[i]]);
            i++;
        }
        if (end0pos != 63) {
            writeBits(EOB);
        }
        return DC;
    }

    private float[] YDU = new float[64];
    private float[] UDU = new float[64];
    private float[] VDU = new float[64];

    private void RGB2YUV(BitmapData img, int xpos, int ypos) {
        int pos = 0;
        for (int y = 0; y < 8; y++) {
            for (int x = 0; x < 8; x++) {
                Color C = img.getPixelColor(xpos + x, img.height - (ypos + y));
                float R = C.r * 255.0f;
                float G = C.g * 255.0f;
                float B = C.b * 255.0f;
                YDU[pos] = (((0.29900f) * R + (0.58700f) * G + (0.11400f) * B)) - 128.0f;
                UDU[pos] = (((-0.16874f) * R + (-0.33126f) * G + (0.50000f) * B));
                VDU[pos] = (((0.50000f) * R + (-0.41869f) * G + (-0.08131f) * 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 flag--other scripts must watch this to know when they can safely get data out
    public bool isDone = false;

    private BitmapData image;
    private int sf = 0;

    public JPGEncoder(Texture2D texture, float quality) {

        // save out texture data to our own data structure
        image = new BitmapData(texture);

        if (quality <= 0.0f) {
            quality = 1.0f;
        }
        if (quality > 100.0f) {
            quality = 100.0f;
        }
        if (quality < 50.0f) {
            sf = (int)(5000.0f / quality);
        }
        else {
            sf = (int)(200.0f - quality * 2.0f);
        }
    }

    /**
    * Handle our initialization and encoding
    */

    public void doEncoding() {
        isDone = false;

        // Create tables -- technically we could only do this once for multiple encodes
        initHuffmanTbl();
        initCategoryfloat();
        initQuantTables(sf);

        // Do actual encoding
        encode();

        // signal that our data is ok to use now
        isDone = true;

        // tell the thread to stop--not sure if this is actually needed
        image = null;
    }

    /**
     * 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
     */

    private void encode() {

        // 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
        float DCY = 0.0f;
        float DCU = 0.0f;
        float DCV = 0.0f;
        bytenew = 0;
        bytepos = 7;
        for (int ypos = 0; ypos < image.height; ypos += 8) {
            for (int xpos = 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);

                // let other threads do stuff too
                //Thread.Sleep(0);
            }
        }

        // Do the bit alignment of the EOI marker
        if (bytepos >= 0) {
            BitString fillbits = new BitString();
            fillbits.len = bytepos + 1;
            fillbits.val = (1 << (bytepos + 1)) - 1;
            writeBits(fillbits);
        }

        writeWord(0xFFD9); //EOI

        //return byteout;
        isDone = true;
    }
}

/*
* Ported to UnityScript by Matthew Wegner, Flashbang Studios
*
* Original code is from as3corelib, found here:
* http://code.google.com/p/as3corelib/source/browse/trunk/src/com/adobe/images/JPGEncoder.as
*
* Original copyright notice is below:
*/

/*
* Ported to C# by Tony McBride
*
* C# version isnt threaded so just call like this:
* JPGEncoder NewEncoder = new JPGEncoder( MyTexture , 75.0f );
* NewEncoder.doEncoding();
* byte[] TexData = NewEncoder.GetBytes();
*/

/*
  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.
*/