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/*
* 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 "vp9/common/vp9_common.h"
#include "vp9/common/vp9_quant_common.h"
#include "vp9/common/vp9_seg_common.h"
static int16_t dc_qlookup[QINDEX_RANGE];
static int16_t ac_qlookup[QINDEX_RANGE];
#define ACDC_MIN 8
// TODO(dkovalev) move to common and reuse
static double poly3(double a, double b, double c, double d, double x) {
return a*x*x*x + b*x*x + c*x + d;
}
void vp9_init_quant_tables() {
int i, val = 4;
// A "real" q of 1.0 forces lossless mode.
// In practice non lossless Q's between 1.0 and 2.0 (represented here by
// integer values from 5-7 give poor rd results (lower psnr and often
// larger size than the lossless encode. To block out those "not very useful"
// values we increment the ac and dc q lookup values by 4 after position 0.
ac_qlookup[0] = val;
dc_qlookup[0] = val;
val += 4;
for (i = 1; i < QINDEX_RANGE; i++) {
const int ac_val = val;
val = (int)(val * 1.01975);
if (val == ac_val)
++val;
ac_qlookup[i] = (int16_t)ac_val;
dc_qlookup[i] = (int16_t)MAX(ACDC_MIN, poly3(0.000000305, -0.00065, 0.9,
0.5, ac_val));
}
}
int16_t vp9_dc_quant(int qindex, int delta) {
return dc_qlookup[clamp(qindex + delta, 0, MAXQ)];
}
int16_t vp9_ac_quant(int qindex, int delta) {
return ac_qlookup[clamp(qindex + delta, 0, MAXQ)];
}
int vp9_get_qindex(MACROBLOCKD *xd, int segment_id, int base_qindex) {
if (vp9_segfeature_active(xd, segment_id, SEG_LVL_ALT_Q)) {
const int data = vp9_get_segdata(xd, segment_id, SEG_LVL_ALT_Q);
return xd->mb_segment_abs_delta == SEGMENT_ABSDATA ?
data : // Abs value
clamp(base_qindex + data, 0, MAXQ); // Delta value
} else {
return base_qindex;
}
}
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