shithub: libvpx

ref: 411f9e2b7f1cb93e6251421faf433b0b2f56e0b0
dir: /vp8/common/quant_common.c/

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */


#include "quant_common.h"

static int dc_qlookup[QINDEX_RANGE];
static int ac_qlookup[QINDEX_RANGE];

#define ACDC_MIN 4

void vp8_init_quant_tables() {
  int i;
  int current_val = 4;
  int last_val = 4;
  int ac_val;

  for (i = 0; i < QINDEX_RANGE; i++) {
    ac_qlookup[i] = current_val;
    current_val = (int)((double)current_val * 1.02);
    if (current_val == last_val)
      current_val++;
    last_val = current_val;

    ac_val = ac_qlookup[i];
    dc_qlookup[i] = (0.000000305 * ac_val * ac_val * ac_val) +
                    (-0.00065 * ac_val * ac_val) +
                    (0.9 * ac_val) + 0.5;
    if (dc_qlookup[i] < ACDC_MIN)
      dc_qlookup[i] = ACDC_MIN;
  }
}

int vp8_dc_quant(int QIndex, int Delta) {
  int retval;

  QIndex = QIndex + Delta;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = dc_qlookup[ QIndex ];
  return retval;
}

int vp8_dc2quant(int QIndex, int Delta) {
  int retval;

  QIndex = QIndex + Delta;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = dc_qlookup[ QIndex ];

  return retval;

}
int vp8_dc_uv_quant(int QIndex, int Delta) {
  int retval;

  QIndex = QIndex + Delta;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = dc_qlookup[ QIndex ];

  return retval;
}

int vp8_ac_yquant(int QIndex) {
  int retval;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = ac_qlookup[ QIndex ];
  return retval;
}

int vp8_ac2quant(int QIndex, int Delta) {
  int retval;

  QIndex = QIndex + Delta;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = (ac_qlookup[ QIndex ] * 775) / 1000;
  if (retval < 4)
    retval = 4;

  return retval;
}
int vp8_ac_uv_quant(int QIndex, int Delta) {
  int retval;

  QIndex = QIndex + Delta;

  if (QIndex > MAXQ)
    QIndex = MAXQ;
  else if (QIndex < 0)
    QIndex = 0;

  retval = ac_qlookup[ QIndex ];
  return retval;
}