prederrorcod.c

Nokia H.264/AVC Encoder/Decoder Usage Manual

/*
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limited license under copyrights owned by Nokia to use the Software for 
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distributing (including the right to make modifications to the Software) 
a fully compliant decoder implementation (hereinafter "Decoder") of 
ITU-T Recommendation H.264 / ISO/IEC International Standard 14496-10 and 
an encoder implementation producing output that is decodable with the 
Decoder.

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*/



#include <string.h>

#include "globals.h"
#include "transform.h"
#include "vlcutility.h"
#include "prederrordec.h"


/*
 *
 * pecCodeBlock:
 *
 * Parameters:
 *      orig                  Original pixels for a block
 *      pred                  Predicted pixels for a block
 *      coef                  Return pointer for coefficients
 *      qp                    Quantization parameter
 *      picType               Type of picture (intra/inter)
 *
 * Function:
 *      Compute prediction error block, transform it and quantize coefficients
 *
 * Returns:
 *      Number of nonzero coefficients
 */
int pecCodeBlock(u_int8 orig[BLK_SIZE][MBK_SIZE],
                 u_int8 pred[BLK_SIZE][MBK_SIZE],
                 int coef[BLK_SIZE][BLK_SIZE],
                 int skip,
                 int qp, 
                 int picType)
{
  int nonZero;
  int i, j;

  for (j = 0; j < BLK_SIZE; j++)
    for (i = 0; i < BLK_SIZE; i++)
      coef[j][i] = orig[j][i] - pred[j][i];
  
  /* 4x4 DCT */
  traDCT4x4(coef);

  /* Normal quantization */

  // in JM, quantization for intra16x16 is handled as in an I-frame
  nonZero = traQuant4x4(&coef[0][0], skip, qp, picType);

  return nonZero;
}


/*
 *
 * pecCodeMB:
 *
 * Parameters:
 *      mb                    Macroblock structure
 *      picType               Type of picture (intra/inter)
 *
 * Function:
 *      Transform and quantize prediction error of all luma blocks in MB
 *
 * Returns:
 *      -
 */
void pecCodeLumaMB(macroblock_s *pMb, 
                   u_int8 pred[MBK_SIZE][MBK_SIZE],
                   int skip,
                   int picType)
{
  int coefQ[BLK_SIZE*BLK_SIZE];
  int mbCoefCost, coefCost;
  int mbNonZeros, blk8x8NonZeros;
  int blk8x8, blkIdx;
  int nonZero;

  pMb->cbpY = 0;

  /*
  * Luma AC DCT & quantization
  */

  mbCoefCost = 0;  /* Set MB coef cost to zero */
  mbNonZeros = 0;

  for (blk8x8 = 0; blk8x8 < 16; blk8x8 += 4)
  {
    coefCost = 0;  /* Set 8x8 block coef cost to zero */
    blk8x8NonZeros = 0;

    for (blkIdx = blk8x8; blkIdx < (blk8x8 + 4); blkIdx ++)
    {
      int blkX, blkY;

      blkX = blkRasterOrder[blkIdx] & 3;
      blkY = blkRasterOrder[blkIdx] >> 2;

      nonZero = pecCodeBlock(
        (u_int8 (*) [MBK_SIZE]) & pMb->origY[blkY * BLK_SIZE][blkX * BLK_SIZE],
        (u_int8 (*) [MBK_SIZE]) & pred[blkY * BLK_SIZE][blkX * BLK_SIZE],
        pMb->coefY[blkIdx],
        skip, pMb->qp, picType);

      // record DC coefficient anyway
      pMb->dcCoefY[blkY][blkX] = pMb->coefY[blkIdx][0][0];

      if (nonZero)
      {
        // Update luma CBP
        pMb->cbpY |= 1 << blkIdx;

        if (pMb->coeffElim)
        {
          blk8x8NonZeros += nonZero;
          vlcuZigZagScan4x4(pMb->coefY[blkIdx], coefQ);
          coefCost += traGetCoefCost(coefQ + skip, nonZero);
        }
      }
    }

    /* Set INTER 8x8 block to zero if coefficient cost */
    /* for block is below threshold                    */

    if (pMb->coeffElim)
    {
      if (coefCost <= pMb->coeffElimTh8x8 && blk8x8NonZeros > 0) {
        blk8x8NonZeros = 0;
        pMb->cbpY &= ~(0x0F << blk8x8);
        memset(pMb->coefY[blk8x8], 0, 4 * BLK_SIZE * BLK_SIZE * sizeof(int));
      }

      mbCoefCost += coefCost;
      mbNonZeros += blk8x8NonZeros;
    }
  }

  /* Set INTER MB to zero, if coefficient cost for MB is below threshold */
  if (pMb->coeffElim)
  {
    if (mbCoefCost <= pMb->coeffElimThLuma && mbNonZeros > 0) {
      memset(pMb->coefY, 0, MBK_SIZE*MBK_SIZE*sizeof(int));
      pMb->cbpY = 0;
    }
  }

  /*
  * Transform and quantize luma DC (if 16x16 intra mode)
  */

  pMb->lumaNonzeroDC = 0;
  if (skip) {
    /* 4x4 DC DCT */
    traHada4x4(pMb->dcCoefY);

    /* Quant */

    // DBG, check the second from the last parameter, different for luma and chroma
    pMb->lumaNonzeroDC = traQuantDC
      (& pMb->dcCoefY[0][0], pMb->qp, picType, BLK_PER_MB*BLK_PER_MB, 0);
  }
}


/*
 *
 * pecCodeChromaMB:
 *
 * Parameters:
 *      pMb                   Macroblock structure
 *      picType               Type of picture (intra/inter)
 *
 * Function:
 *      Transform and quantize prediction error of all chroma blocks in MB
 *
 * Returns:
 *      -
 */
void pecCodeChromaMB(macroblock_s *pMb, 
                     u_int8 predC[MBK_SIZE/2][2*(MBK_SIZE/2)],
                     int picType)
{
  int comp, blkIdxX, blkIdxY;
  int coefQ[BLK_SIZE*BLK_SIZE];
  int mbCoefCost;
  int totalNonZero;
  int nonZero;
  int cbpBit;

  pMb->cbpChromaDC = pMb->cbpC = 0;
  cbpBit = 1;

  for (comp = 0; comp < 2; comp++) {

    /*
     * Chroma AC transform and quantization
     */

    mbCoefCost = 0;  /* Set MB coef cost to zero */

    totalNonZero = 0;
    for (blkIdxY = 0; blkIdxY < BLK_PER_MB/2; blkIdxY ++) {
      for (blkIdxX = 0; blkIdxX < BLK_PER_MB/2; blkIdxX ++) {

        nonZero = pecCodeBlock(
          (u_int8 (*) [MBK_SIZE]) & pMb->origC[blkIdxY*BLK_SIZE][comp*(MBK_SIZE/2)+blkIdxX*BLK_SIZE],
          (u_int8 (*) [MBK_SIZE]) & predC[blkIdxY*BLK_SIZE][comp*(MBK_SIZE/2)+blkIdxX*BLK_SIZE],
          pMb->coefC[comp][blkIdxY][blkIdxX], 1, pMb->qpC, picType);

        /* Take DC coef out */
        pMb->dcCoefC[comp][blkIdxY][blkIdxX] = 
          pMb->coefC[comp][blkIdxY][blkIdxX][0][0];

        if (nonZero)
        {
          if (pMb->coeffElim)
          {
            totalNonZero += nonZero;
            vlcuZigZagScan4x4(pMb->coefC[comp][blkIdxY][blkIdxX], coefQ);
            mbCoefCost += traGetCoefCost(coefQ + 1, nonZero);
          }

          pMb->cbpC |= cbpBit;
        }

        cbpBit <<= 1;
      }
    }

    /* Set INTER Chroma MB to zero, if coefficient cost for MB is below threshold */
    if ((pMb->coeffElim) && (mbCoefCost <= pMb->coeffElimThChroma) && (totalNonZero > 0))
    {
      int cbpMask;

      cbpMask = (1 << (BLK_PER_MB/2*BLK_PER_MB/2)) - 1;
      pMb->cbpC &= ~(cbpMask << (comp*(BLK_PER_MB/2*BLK_PER_MB/2)));
      memset(pMb->coefC[comp], 0, MBK_SIZE/2*MBK_SIZE/2*sizeof(int));
    }

    /*
     * Chroma DC transform and quantization
     */

    /* 2x2 DC DCT */
    traDCT2x2(pMb->dcCoefC[comp]);

    /* 2x2 DC quant */

    // DBG treat chroma and luma differently
    nonZero = traQuantDC(& pMb->dcCoefC[comp][0][0], 
                         pMb->qpC, picType, BLK_PER_MB/2*BLK_PER_MB/2, 1);

    /* Update chroma CBP */
    if (nonZero)
      pMb->cbpChromaDC |= 1 << comp;
  }
}