grfmt_jpeg.cpp.svn-base

来自「非结构化路识别」· SVN-BASE 代码 · 共 1,652 行 · 第 1/4 页

}


/****************************** JPEG (JFIF) reader ***************************/

// zigzag & IDCT prescaling (AAN algorithm) tables
static const uchar zigzag[] =
{
  0,  8,  1,  2,  9, 16, 24, 17, 10,  3,  4, 11, 18, 25, 32, 40,
 33, 26, 19, 12,  5,  6, 13, 20, 27, 34, 41, 48, 56, 49, 42, 35,
 28, 21, 14,  7, 15, 22, 29, 36, 43, 50, 57, 58, 51, 44, 37, 30,
 23, 31, 38, 45, 52, 59, 60, 53, 46, 39, 47, 54, 61, 62, 55, 63,
 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63
};


static const int idct_prescale[] =
{
    16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
    22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
    21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
    19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
    16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
    12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
     8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
     4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
};


#define fixb         14
#define fix(x, n)    (int)((x)*(1 << (n)) + .5)
#define fix1(x, n)   (x)
#define fixmul(x)    (x)
#define postscale(x) round(x)

#define C0_707     fix( 0.707106781f, fixb )
#define C0_924     fix( 0.923879533f, fixb )
#define C0_541     fix( 0.541196100f, fixb )
#define C0_382     fix( 0.382683432f, fixb )
#define C1_306     fix( 1.306562965f, fixb )

#define C1_082     fix( 1.082392200f, fixb )
#define C1_414     fix( 1.414213562f, fixb )
#define C1_847     fix( 1.847759065f, fixb )
#define C2_613     fix( 2.613125930f, fixb )

#define fixc       10
#define b_cb       fix( 1.772, fixc )
#define g_cb      -fix( 0.34414, fixc )
#define g_cr      -fix( 0.71414, fixc )
#define r_cr       fix( 1.402, fixc )

#define y_r        fix( 0.299, fixc )
#define y_g        fix( 0.587, fixc )
#define y_b        fix( 0.114, fixc )

#define cb_r      -fix( 0.1687, fixc )
#define cb_g      -fix( 0.3313, fixc )
#define cb_b       fix( 0.5,    fixc )

#define cr_r       fix( 0.5,    fixc )
#define cr_g      -fix( 0.4187, fixc )
#define cr_b      -fix( 0.0813, fixc )


// IDCT without prescaling
static void aan_idct8x8( int *src, int *dst, int step )
{
    int   workspace[64], *work = workspace;
    int   i;

    /* Pass 1: process rows */
    for( i = 8; i > 0; i--, src += 8, work += 8 )
    {
        /* Odd part */
        int  x0 = src[5], x1 = src[3];
        int  x2 = src[1], x3 = src[7];

        int  x4 = x0 + x1; x0 -= x1;

        x1 = x2 + x3; x2 -= x3;
        x3 = x1 + x4; x1 -= x4;

        x4 = (x0 + x2)*C1_847;
        x0 = descale( x4 - x0*C2_613, fixb);
        x2 = descale( x2*C1_082 - x4, fixb);
        x1 = descale( x1*C1_414, fixb);

        x0 -= x3;
        x1 -= x0;
        x2 += x1;

        work[7] = x3; work[6] = x0;
        work[5] = x1; work[4] = x2;

        /* Even part */
        x2 = src[2]; x3 = src[6];
        x0 = src[0]; x1 = src[4];

        x4 = x2 + x3;
        x2 = descale((x2-x3)*C1_414, fixb) - x4;

        x3 = x0 + x1; x0 -= x1;
        x1 = x3 + x4; x3 -= x4;
        x4 = x0 + x2; x0 -= x2;

        x2 = work[7];
        x1 -= x2; x2 = 2*x2 + x1;
        work[7] = x1; work[0] = x2;

        x2 = work[6];
        x1 = x4 + x2; x4 -= x2;
        work[1] = x1; work[6] = x4;

        x1 = work[5]; x2 = work[4];
        x4 = x0 + x1; x0 -= x1;
        x1 = x3 + x2; x3 -= x2;

        work[2] = x4; work[5] = x0;
        work[3] = x3; work[4] = x1;
    }

    /* Pass 2: process columns */
    work = workspace;
    for( i = 8; i > 0; i--, dst += step, work++ )
    {
        /* Odd part */
        int  x0 = work[8*5], x1 = work[8*3];
        int  x2 = work[8*1], x3 = work[8*7];

        int  x4 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;
        x3 = x1 + x4; x1 -= x4;

        x4 = (x0 + x2)*C1_847;
        x0 = descale( x4 - x0*C2_613, fixb);
        x2 = descale( x2*C1_082 - x4, fixb);
        x1 = descale( x1*C1_414, fixb);

        x0 -= x3;
        x1 -= x0;
        x2 += x1;

        dst[7] = x3; dst[6] = x0;
        dst[5] = x1; dst[4] = x2;

        /* Even part */
        x2 = work[8*2]; x3 = work[8*6];
        x0 = work[8*0]; x1 = work[8*4];

        x4 = x2 + x3;
        x2 = descale((x2-x3)*C1_414, fixb) - x4;

        x3 = x0 + x1; x0 -= x1;
        x1 = x3 + x4; x3 -= x4;
        x4 = x0 + x2; x0 -= x2;

        x2 = dst[7];
        x1 -= x2; x2 = 2*x2 + x1;
        x1 = descale(x1,3);
        x2 = descale(x2,3);

        dst[7] = x1; dst[0] = x2;

        x2 = dst[6];
        x1 = descale(x4 + x2,3);
        x4 = descale(x4 - x2,3);
        dst[1] = x1; dst[6] = x4;

        x1 = dst[5]; x2 = dst[4];

        x4 = descale(x0 + x1,3);
        x0 = descale(x0 - x1,3);
        x1 = descale(x3 + x2,3);
        x3 = descale(x3 - x2,3);
       
        dst[2] = x4; dst[5] = x0;
        dst[3] = x3; dst[4] = x1;
    }
}


static const int max_dec_htable_size = 1 << 12;
static const int first_table_bits = 9;

GrFmtJpegReader::GrFmtJpegReader( const char* filename ) : GrFmtReader( filename )
{
    m_planes= -1;
    m_offset= -1;

    int i;
    for( i = 0; i < 4; i++ )
    {
        m_td[i] = new short[max_dec_htable_size];
        m_ta[i] = new short[max_dec_htable_size];
    }
}


GrFmtJpegReader::~GrFmtJpegReader()
{
    for( int i = 0; i < 4; i++ )
    {
        delete m_td[i];
        m_td[i] = 0;
        delete m_ta[i];
        m_ta[i] = 0;
    }
}


void  GrFmtJpegReader::Close()
{
    m_strm.Close();
    GrFmtReader::Close();
}


bool GrFmtJpegReader::ReadHeader()
{
    char buffer[16];
    int  i;
    bool result = false, is_jfif = false, is_sof = false, 
         is_qt = false, is_ht = false, is_sos = false;
    
    assert( strlen(m_filename) != 0 );
    if( !m_strm.Open( m_filename )) return false;

    memset( m_is_tq, 0, sizeof(m_is_tq));
    memset( m_is_td, 0, sizeof(m_is_td));
    memset( m_is_ta, 0, sizeof(m_is_ta));
    m_MCUs = 0;

    if( setjmp( m_strm.JmpBuf()) == 0 )
    {
        RMByteStream& lstrm = m_strm.m_low_strm;
        
        lstrm.Skip( 2 ); // skip SOI marker
        
        for(;;)
        {
            int marker = m_strm.FindMarker() & 255;

            // check for standalone markers
            if( marker != 0xD8 /* SOI */ && marker != 0xD9 /* EOI */ &&
                marker != 0x01 /* TEM */ && !( 0xD0 <= marker && marker <= 0xD7 ))
            {
                int pos    = lstrm.GetPos();
                int length = lstrm.GetWord();
            
                switch( marker )
                {
                case 0xE0: // APP0
                    lstrm.GetBytes( buffer, 5 );
                    if( strcmp(buffer, "JFIF") == 0 ) // JFIF identification
                    {
                        m_version = lstrm.GetWord();
                        is_jfif = true;
                    }
                    break;

                case 0xC0: // SOF0
                    m_precision = lstrm.GetByte();
                    m_height = lstrm.GetWord();
                    m_width = lstrm.GetWord();
                    m_planes = lstrm.GetByte();

                    if( m_width == 0 || m_height == 0 || // DNL not supported
                       (m_planes != 1 && m_planes != 3)) goto parsing_end;

                    m_iscolor = m_planes == 3;
                
                    memset( m_ci, -1, sizeof(m_ci));

                    for( i = 0; i < m_planes; i++ )
                    {
                        int idx = lstrm.GetByte();

                        if( idx < 1 || idx > m_planes ) // wrong index
                        {
                            idx = i+1; // hack
                        }
                        cmp_info& ci = m_ci[idx-1];
                        
                        if( ci.tq > 0 /* duplicated description */) goto parsing_end;

                        ci.h = (char)lstrm.GetByte();
                        ci.v = (char)(ci.h & 15);
                        ci.h >>= 4;
                        ci.tq = (char)lstrm.GetByte();
                        if( !((ci.h == 1 || ci.h == 2 || ci.h == 4) &&
                              (ci.v == 1 || ci.v == 2 || ci.v == 4) &&
                              ci.tq < 3) ||
                            // chroma mcu-parts should have equal sizes and
                            // be non greater then luma sizes
                            !( i != 2 || (ci.h == m_ci[1].h && ci.v == m_ci[1].v &&
                                          ci.h <= m_ci[0].h && ci.v <= m_ci[0].v)))
                            goto parsing_end;
                    }
                    is_sof = true;
                    m_type = marker - 0xC0;
                    break;

                case 0xDB: // DQT
                    if( !LoadQuantTables( length )) goto parsing_end;
                    is_qt = true;
                    break;

                case 0xC4: // DHT
                    if( !LoadHuffmanTables( length )) goto parsing_end;
                    is_ht = true;
                    break;

                case 0xDA: // SOS
                    is_sos = true;
                    m_offset = pos - 2;
                    goto parsing_end;

                case 0xDD: // DRI
                    m_MCUs = lstrm.GetWord();
                    break;
                }
                lstrm.SetPos( pos + length );
            }
        }
parsing_end: ;
    }

    result = /*is_jfif &&*/ is_sof && is_qt && is_ht && is_sos;
    if( !result )
    {
        m_width = m_height = -1;
        m_offset = -1;
        m_strm.Close();
    }
    return result;
}


bool GrFmtJpegReader::LoadQuantTables( int length )
{
    uchar buffer[128];
    int  i, tq_size;
    
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int tq = lstrm.GetByte();
        int size = tq >> 4;
        tq &= 15;

        tq_size = (64<<size) + 1; 
        if( tq > 3 || size > 1 || length < tq_size ) return false;
        length -= tq_size;

        lstrm.GetBytes( buffer, tq_size - 1 );
        
        if( size == 0 ) // 8 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = buffer[i] * 16 * idct_prescale[idx];
            }
        }
        else // 16 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = ((unsigned short*)buffer)[i] * idct_prescale[idx];
            }
        }
        m_is_tq[tq] = true;
    }

    return true;
}


bool GrFmtJpegReader::LoadHuffmanTables( int length )
{
    const int max_bits = 16;
    uchar buffer[1024];
    int  buffer2[1024];

    int  i, ht_size;
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int t = lstrm.GetByte();
        int hclass = t >> 4;
        t &= 15;

        if( t > 3 || hclass > 1 || length < 17 ) return false;
        length -= 17;

        lstrm.GetBytes( buffer, max_bits );
        for( i = 0, ht_size = 0; i < max_bits; i++ ) ht_size += buffer[i];

        if( length < ht_size ) return false;
        length -= ht_size;

        lstrm.GetBytes( buffer + max_bits, ht_size );
        
        if( !::bsCreateDecodeHuffmanTable( 
                  ::bsCreateSourceHuffmanTable( 
                        buffer, buffer2, max_bits, first_table_bits ),
                        hclass == 0 ? m_td[t] : m_ta[t],