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/*---------------------------------------------------------------------------

*

*  Course:   System Design II

*

*  Module:   quantize.c

*

*  Purpose:  Quantization functions for H.263 encoder

*

*  Notes:    Only INTRA MB:s supported

*

*  Author:   Tero Kangas and Olli Lehtoranta

*

*  History:  28/10/2002: + Original version ready

*

**---------------------------------------------------------------------------

*/

#include "headers.h"

/*---------------------------------------------------------------------------

*

*  Function: quantizeIntraMB

*

*  Input:    QP = H.263 quantization parameter

*            MB = pointer to macroblock data

*

*  Return:   none

*

*  Purpose:  Correct quantization for Intra macroblock. The DC

*            coefficients are processed separately. Also sets the coded

*            block pattern for given macroblock.

*

**---------------------------------------------------------------------------

*/

void quantizeIntraMB( const sint32 QP, MBType * const MB ) {

  sint32 block, i;

  sint32 dc;

  sint32 cbp;

  sint32 qLevel;

  sint32 origCoeff;

  sint32 twiceTheQP = QP*2;

  sint32 zeroBlockIndication = 0;

  sint16 *pMB;

  cbp = 0;

  pMB = MB->data;

  for( block=0; block<6; block++ ) {

    /* Special quantization for DC coefficient  */

    dc = *pMB;

    dc = dc / 8;

    CLIP(1,dc,254);

    *(pMB++) = (sint16)dc;

    #ifdef ENC_DEBUG

    printf("o: %x ", (uint16)dc);

    #endif

    for(i=1; i<64; i++ ) {

      origCoeff = *pMB;

      qLevel = abs(origCoeff) / twiceTheQP;

      if( qLevel > 127 )

          qLevel = 127;

      zeroBlockIndication = zeroBlockIndication | qLevel;

      if( origCoeff < 0 )

          qLevel = -qLevel;

      *(pMB++) = (sint16)qLevel;

      #ifdef ENC_DEBUG

      printf("%x ", (uint16)qLevel);

      #endif

    }

    #ifdef ENC_DEBUG

    printf("\r\n");

    #endif

    if( zeroBlockIndication != 0 ){

      /* Set block pattern accordingly */

      cbp = cbp | ( 1 << ( 5 - block ) );

      zeroBlockIndication = 0;

    }

  }

  MB->cbp = cbp;

}

/*---------------------------------------------------------------------------

*

*  Function: quantizeIntraMBInverse

*

*  Input:    QP = H.263 quantization parameter

*            MB = pointer to macroblock data

*

*  Return:   none

*

*  Purpose:  Inverse quantization of Intra macroblock. DC values are processed

*            separately. In addition, no inverse quantization is

*            performed if coded block pattern says that there are no

*            AC coefficients present. In this case the 8 x 8 matrix

*            is filled with zeros (Simplification of computations).

*

**---------------------------------------------------------------------------

*/

void quantizeIntraMBInverse( const sint32 QP, MBType * const MB ){

  sint32 block, i;

  sint32 reconCoeff;

  sint32 origCoeff;

  sint32 bias;

  sint32 mask = 32;

  sint16 *pMB;

  /* Odd/even determination and inverse quantization formula bias  */

  bias = 0;

  if( ( QP & 1 ) == 0 )

      bias = 1;

  pMB = MB->data;

  for( block = 0; block < 6; block++ ) {

    /* DC coeff */

    *(pMB++) = (sint16)(8 * MB->data[64*block]);

    /* The inverse quantization for AC coeffs is needed

       on if there are nonzero coefficients in MB */

    if( ( MB->cbp & mask ) != 0 ){

      /* The were nonzero AC-coefficients */

      for( i=1; i<64; i++ ) {

          origCoeff = *pMB;

          reconCoeff = QP * ( 2 * abs(origCoeff) + 1 ) - bias;

          if( origCoeff < 0 )

              reconCoeff = -reconCoeff;

          else if( origCoeff == 0 )

              reconCoeff = 0;

          *(pMB++) = (sint16)reconCoeff;

      }

    } else {

      /* All AC coeffs are zero -> nothing needs to be done */

    }

    mask = mask >> 1;

  }

}