quant.c

mediastreamer2是开源的网络传输媒体流的库

      quantized_list[ZigZagPtr[0]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[0] <= -FquantZBinSizePtr[0] ) {
      temp = FquantCoeffsPtr[0] *
        ( DCT_blockPtr[0] - FquantRoundPtr[0] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[0]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 1 */
    if ( DCT_blockPtr[1] >= FquantZBinSizePtr[1] ) {
      temp = FquantCoeffsPtr[1] *
        ( DCT_blockPtr[1] + FquantRoundPtr[1] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[1]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[1] <= -FquantZBinSizePtr[1] ) {
      temp = FquantCoeffsPtr[1] *
        ( DCT_blockPtr[1] - FquantRoundPtr[1] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[1]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 2 */
    if ( DCT_blockPtr[2] >= FquantZBinSizePtr[2] ) {
      temp = FquantCoeffsPtr[2] *
        ( DCT_blockPtr[2] + FquantRoundPtr[2] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[2]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[2] <= -FquantZBinSizePtr[2] ) {
      temp = FquantCoeffsPtr[2] *
        ( DCT_blockPtr[2] - FquantRoundPtr[2] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[2]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 3 */
    if ( DCT_blockPtr[3] >= FquantZBinSizePtr[3] ) {
      temp = FquantCoeffsPtr[3] *
        ( DCT_blockPtr[3] + FquantRoundPtr[3] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[3]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[3] <= -FquantZBinSizePtr[3] ) {
      temp = FquantCoeffsPtr[3] *
        ( DCT_blockPtr[3] - FquantRoundPtr[3] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[3]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 4 */
    if ( DCT_blockPtr[4] >= FquantZBinSizePtr[4] ) {
      temp = FquantCoeffsPtr[4] *
        ( DCT_blockPtr[4] + FquantRoundPtr[4] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[4]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[4] <= -FquantZBinSizePtr[4] ) {
      temp = FquantCoeffsPtr[4] *
        ( DCT_blockPtr[4] - FquantRoundPtr[4] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[4]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 5 */
    if ( DCT_blockPtr[5] >= FquantZBinSizePtr[5] ) {
      temp = FquantCoeffsPtr[5] *
        ( DCT_blockPtr[5] + FquantRoundPtr[5] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[5]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[5] <= -FquantZBinSizePtr[5] ) {
      temp = FquantCoeffsPtr[5] *
        ( DCT_blockPtr[5] - FquantRoundPtr[5] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[5]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 6 */
    if ( DCT_blockPtr[6] >= FquantZBinSizePtr[6] ) {
      temp = FquantCoeffsPtr[6] *
        ( DCT_blockPtr[6] + FquantRoundPtr[6] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[6]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[6] <= -FquantZBinSizePtr[6] ) {
      temp = FquantCoeffsPtr[6] *
        ( DCT_blockPtr[6] - FquantRoundPtr[6] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[6]] = ( val < -511 ) ? -511 : val;
    }

    /* Column 7 */
    if ( DCT_blockPtr[7] >= FquantZBinSizePtr[7] ) {
      temp = FquantCoeffsPtr[7] *
        ( DCT_blockPtr[7] + FquantRoundPtr[7] ) ;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[7]] = ( val > 511 ) ? 511 : val;
    } else if ( DCT_blockPtr[7] <= -FquantZBinSizePtr[7] ) {
      temp = FquantCoeffsPtr[7] *
        ( DCT_blockPtr[7] - FquantRoundPtr[7] ) + MIN16;
      val = (Q_LIST_ENTRY) (temp>>16);
      quantized_list[ZigZagPtr[7]] = ( val < -511 ) ? -511 : val;
    }

    FquantRoundPtr += 8;
    FquantCoeffsPtr += 8;
    FquantZBinSizePtr += 8;
    DCT_blockPtr += 8;
    ZigZagPtr += 8;
  }
}

static void init_dequantizer ( PB_INSTANCE *pbi,
                        ogg_uint32_t scale_factor,
                        unsigned char  QIndex ){
  int i, j;

  Q_LIST_ENTRY * InterY_coeffs;
  Q_LIST_ENTRY * InterU_coeffs;
  Q_LIST_ENTRY * InterV_coeffs;
  Q_LIST_ENTRY * Y_coeffs;
  Q_LIST_ENTRY * U_coeffs;
  Q_LIST_ENTRY * V_coeffs;
  Q_LIST_ENTRY * DcScaleFactorTable;

  InterY_coeffs = pbi->InterY_coeffs;
  InterU_coeffs = pbi->InterU_coeffs;
  InterV_coeffs = pbi->InterV_coeffs;
  Y_coeffs = pbi->Y_coeffs;
  U_coeffs = pbi->U_coeffs;
  V_coeffs = pbi->V_coeffs;
  DcScaleFactorTable = pbi->DcScaleFactorTable;

  /* invert the dequant index into the quant index
     the dxer has a different order than the cxer. */
  BuildZigZagIndex(pbi);

  /* Reorder dequantisation coefficients into dct zigzag order. */
  for ( i = 0; i < BLOCK_SIZE; i++ ) {
    j = pbi->zigzag_index[i];
    pbi->dequant_Y_coeffs[j] = Y_coeffs[i];
  }
  for ( i = 0; i < BLOCK_SIZE; i++ ) {
    j = pbi->zigzag_index[i];
    pbi->dequant_U_coeffs[j] = U_coeffs[i];
  }
  for ( i = 0; i < BLOCK_SIZE; i++ ) {
    j = pbi->zigzag_index[i];
    pbi->dequant_V_coeffs[j] = V_coeffs[i];
  }
  for ( i = 0; i < BLOCK_SIZE; i++ ){
    j = pbi->zigzag_index[i];
    pbi->dequant_InterY_coeffs[j] = InterY_coeffs[i];
  }
  for ( i = 0; i < BLOCK_SIZE; i++ ){
    j = pbi->zigzag_index[i];
    pbi->dequant_InterU_coeffs[j] = InterU_coeffs[i];
  }
  for ( i = 0; i < BLOCK_SIZE; i++ ){
    j = pbi->zigzag_index[i];
    pbi->dequant_InterV_coeffs[j] = InterV_coeffs[i];
  }

  /* Intra Y DC coeff */
  pbi->dequant_Y_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_Y_coeffs[0])/100);
  if ( pbi->dequant_Y_coeffs[0] < MIN_DEQUANT_VAL * 2 )
    pbi->dequant_Y_coeffs[0] = MIN_DEQUANT_VAL * 2;
  pbi->dequant_Y_coeffs[0] =
    pbi->dequant_Y_coeffs[0] << IDCT_SCALE_FACTOR;

  /* Intra UV */
  pbi->dequant_U_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_U_coeffs[0])/100);
  if ( pbi->dequant_U_coeffs[0] < MIN_DEQUANT_VAL * 2 )
    pbi->dequant_U_coeffs[0] = MIN_DEQUANT_VAL * 2;
  pbi->dequant_U_coeffs[0] =
    pbi->dequant_U_coeffs[0] << IDCT_SCALE_FACTOR;
  pbi->dequant_V_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_V_coeffs[0])/100);
  if ( pbi->dequant_V_coeffs[0] < MIN_DEQUANT_VAL * 2 )
    pbi->dequant_V_coeffs[0] = MIN_DEQUANT_VAL * 2;
  pbi->dequant_V_coeffs[0] =
    pbi->dequant_V_coeffs[0] << IDCT_SCALE_FACTOR;

  /* Inter Y DC coeff */
  pbi->dequant_InterY_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_InterY_coeffs[0])/100);
  if ( pbi->dequant_InterY_coeffs[0] < MIN_DEQUANT_VAL * 4 )
    pbi->dequant_InterY_coeffs[0] = MIN_DEQUANT_VAL * 4;
  pbi->dequant_InterY_coeffs[0] =
    pbi->dequant_InterY_coeffs[0] << IDCT_SCALE_FACTOR;

  /* Inter UV */
  pbi->dequant_InterU_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_InterU_coeffs[0])/100);
  if ( pbi->dequant_InterU_coeffs[0] < MIN_DEQUANT_VAL * 4 )
    pbi->dequant_InterU_coeffs[0] = MIN_DEQUANT_VAL * 4;
  pbi->dequant_InterU_coeffs[0] =
    pbi->dequant_InterU_coeffs[0] << IDCT_SCALE_FACTOR;
  pbi->dequant_InterV_coeffs[0] =
    ((DcScaleFactorTable[QIndex] * pbi->dequant_InterV_coeffs[0])/100);
  if ( pbi->dequant_InterV_coeffs[0] < MIN_DEQUANT_VAL * 4 )
    pbi->dequant_InterV_coeffs[0] = MIN_DEQUANT_VAL * 4;
  pbi->dequant_InterV_coeffs[0] =
    pbi->dequant_InterV_coeffs[0] << IDCT_SCALE_FACTOR;

  for ( i = 1; i < BLOCK_SIZE; i++ ){
    /* now scale coefficients by required compression factor */
    pbi->dequant_Y_coeffs[i] =
      (( scale_factor * pbi->dequant_Y_coeffs[i] ) / 100);
    if ( pbi->dequant_Y_coeffs[i] < MIN_DEQUANT_VAL )
      pbi->dequant_Y_coeffs[i] = MIN_DEQUANT_VAL;
    pbi->dequant_Y_coeffs[i] =
      pbi->dequant_Y_coeffs[i] << IDCT_SCALE_FACTOR;

    pbi->dequant_U_coeffs[i] =
      (( scale_factor * pbi->dequant_U_coeffs[i] ) / 100);
    if ( pbi->dequant_U_coeffs[i] < MIN_DEQUANT_VAL )
      pbi->dequant_U_coeffs[i] = MIN_DEQUANT_VAL;
    pbi->dequant_U_coeffs[i] =
      pbi->dequant_U_coeffs[i] << IDCT_SCALE_FACTOR;

    pbi->dequant_V_coeffs[i] =
      (( scale_factor * pbi->dequant_V_coeffs[i] ) / 100);
    if ( pbi->dequant_V_coeffs[i] < MIN_DEQUANT_VAL )
      pbi->dequant_V_coeffs[i] = MIN_DEQUANT_VAL;
    pbi->dequant_V_coeffs[i] =
      pbi->dequant_V_coeffs[i] << IDCT_SCALE_FACTOR;

    pbi->dequant_InterY_coeffs[i] =
      (( scale_factor * pbi->dequant_InterY_coeffs[i] ) / 100);
    if ( pbi->dequant_InterY_coeffs[i] < (MIN_DEQUANT_VAL * 2) )
      pbi->dequant_InterY_coeffs[i] = MIN_DEQUANT_VAL * 2;
    pbi->dequant_InterY_coeffs[i] =
      pbi->dequant_InterY_coeffs[i] << IDCT_SCALE_FACTOR;

    pbi->dequant_InterU_coeffs[i] =
      (( scale_factor * pbi->dequant_InterU_coeffs[i] ) / 100);
    if ( pbi->dequant_InterU_coeffs[i] < (MIN_DEQUANT_VAL * 2) )
      pbi->dequant_InterU_coeffs[i] = MIN_DEQUANT_VAL * 2;
    pbi->dequant_InterU_coeffs[i] =
      pbi->dequant_InterU_coeffs[i] << IDCT_SCALE_FACTOR;

    pbi->dequant_InterV_coeffs[i] =
      (( scale_factor * pbi->dequant_InterV_coeffs[i] ) / 100);
    if ( pbi->dequant_InterV_coeffs[i] < (MIN_DEQUANT_VAL * 2) )
      pbi->dequant_InterV_coeffs[i] = MIN_DEQUANT_VAL * 2;
    pbi->dequant_InterV_coeffs[i] =
      pbi->dequant_InterV_coeffs[i] << IDCT_SCALE_FACTOR;
  }

  pbi->dequant_coeffs = pbi->dequant_Y_coeffs;
}

void UpdateQ( PB_INSTANCE *pbi, int NewQIndex ){
  ogg_uint32_t qscale;

  /* clamp to legal bounds */
  if (NewQIndex >= Q_TABLE_SIZE) NewQIndex = Q_TABLE_SIZE - 1;
  else if (NewQIndex < 0) NewQIndex = 0;

  pbi->FrameQIndex = NewQIndex;
  qscale = pbi->QThreshTable[NewQIndex];
  pbi->ThisFrameQualityValue = qscale;

  /* Re-initialise the Q tables for forward and reverse transforms. */
  init_dequantizer ( pbi, qscale, (unsigned char) pbi->FrameQIndex );
}

void UpdateQC( CP_INSTANCE *cpi, ogg_uint32_t NewQ ){
  ogg_uint32_t qscale;
  PB_INSTANCE *pbi = &cpi->pb;

  /* Do bounds checking and convert to a float.  */
  qscale = NewQ;
  if ( qscale < pbi->QThreshTable[Q_TABLE_SIZE-1] )
    qscale = pbi->QThreshTable[Q_TABLE_SIZE-1];
  else if ( qscale > pbi->QThreshTable[0] )
    qscale = pbi->QThreshTable[0];

  /* Set the inter/intra descision control variables. */
  pbi->FrameQIndex = Q_TABLE_SIZE - 1;
  while ((ogg_int32_t) pbi->FrameQIndex >= 0 ) {
    if ( (pbi->FrameQIndex == 0) ||
         ( pbi->QThreshTable[pbi->FrameQIndex] >= NewQ) )
      break;
    pbi->FrameQIndex --;
  }

  /* Re-initialise the Q tables for forward and reverse transforms. */
  init_quantizer ( cpi, qscale, (unsigned char) pbi->FrameQIndex );
  init_dequantizer ( pbi, qscale, (unsigned char) pbi->FrameQIndex );
}