280 lines
8.5 KiB
C
280 lines
8.5 KiB
C
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/*
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* AAC encoder utilities
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* Copyright (C) 2015 Rostislav Pehlivanov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* AAC encoder utilities
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* @author Rostislav Pehlivanov ( atomnuker gmail com )
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*/
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#ifndef AVCODEC_AACENC_UTILS_H
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#define AVCODEC_AACENC_UTILS_H
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#include "libavutil/ffmath.h"
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#include "aac.h"
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#include "aacenctab.h"
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#include "aactab.h"
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#define ROUND_STANDARD 0.4054f
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#define ROUND_TO_ZERO 0.1054f
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#define C_QUANT 0.4054f
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static inline void abs_pow34_v(float *out, const float *in, const int size)
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{
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int i;
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for (i = 0; i < size; i++) {
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float a = fabsf(in[i]);
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out[i] = sqrtf(a * sqrtf(a));
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}
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}
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static inline float pos_pow34(float a)
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{
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return sqrtf(a * sqrtf(a));
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}
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/**
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* Quantize one coefficient.
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* @return absolute value of the quantized coefficient
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* @see 3GPP TS26.403 5.6.2 "Scalefactor determination"
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*/
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static inline int quant(float coef, const float Q, const float rounding)
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{
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float a = coef * Q;
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return sqrtf(a * sqrtf(a)) + rounding;
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}
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static inline void quantize_bands(int *out, const float *in, const float *scaled,
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int size, int is_signed, int maxval, const float Q34,
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const float rounding)
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{
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int i;
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for (i = 0; i < size; i++) {
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float qc = scaled[i] * Q34;
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int tmp = (int)FFMIN(qc + rounding, (float)maxval);
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if (is_signed && in[i] < 0.0f) {
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tmp = -tmp;
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}
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out[i] = tmp;
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}
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}
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static inline float find_max_val(int group_len, int swb_size, const float *scaled)
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{
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float maxval = 0.0f;
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int w2, i;
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for (w2 = 0; w2 < group_len; w2++) {
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for (i = 0; i < swb_size; i++) {
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maxval = FFMAX(maxval, scaled[w2*128+i]);
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}
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}
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return maxval;
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}
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static inline int find_min_book(float maxval, int sf)
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{
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float Q34 = ff_aac_pow34sf_tab[POW_SF2_ZERO - sf + SCALE_ONE_POS - SCALE_DIV_512];
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int qmaxval, cb;
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qmaxval = maxval * Q34 + C_QUANT;
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if (qmaxval >= (FF_ARRAY_ELEMS(aac_maxval_cb)))
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cb = 11;
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else
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cb = aac_maxval_cb[qmaxval];
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return cb;
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}
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static inline float find_form_factor(int group_len, int swb_size, float thresh,
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const float *scaled, float nzslope) {
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const float iswb_size = 1.0f / swb_size;
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const float iswb_sizem1 = 1.0f / (swb_size - 1);
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const float ethresh = thresh;
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float form = 0.0f, weight = 0.0f;
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int w2, i;
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for (w2 = 0; w2 < group_len; w2++) {
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float e = 0.0f, e2 = 0.0f, var = 0.0f, maxval = 0.0f;
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float nzl = 0;
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for (i = 0; i < swb_size; i++) {
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float s = fabsf(scaled[w2*128+i]);
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maxval = FFMAX(maxval, s);
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e += s;
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e2 += s *= s;
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/* We really don't want a hard non-zero-line count, since
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* even below-threshold lines do add up towards band spectral power.
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* So, fall steeply towards zero, but smoothly
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*/
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if (s >= ethresh) {
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nzl += 1.0f;
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} else {
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if (nzslope == 2.f)
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nzl += (s / ethresh) * (s / ethresh);
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else
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nzl += ff_fast_powf(s / ethresh, nzslope);
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}
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}
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if (e2 > thresh) {
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float frm;
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e *= iswb_size;
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/** compute variance */
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for (i = 0; i < swb_size; i++) {
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float d = fabsf(scaled[w2*128+i]) - e;
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var += d*d;
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}
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var = sqrtf(var * iswb_sizem1);
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e2 *= iswb_size;
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frm = e / FFMIN(e+4*var,maxval);
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form += e2 * sqrtf(frm) / FFMAX(0.5f,nzl);
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weight += e2;
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}
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}
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if (weight > 0) {
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return form / weight;
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} else {
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return 1.0f;
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}
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}
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/** Return the minimum scalefactor where the quantized coef does not clip. */
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static inline uint8_t coef2minsf(float coef)
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{
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return av_clip_uint8(log2f(coef)*4 - 69 + SCALE_ONE_POS - SCALE_DIV_512);
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}
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/** Return the maximum scalefactor where the quantized coef is not zero. */
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static inline uint8_t coef2maxsf(float coef)
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{
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return av_clip_uint8(log2f(coef)*4 + 6 + SCALE_ONE_POS - SCALE_DIV_512);
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}
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/*
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* Returns the closest possible index to an array of float values, given a value.
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*/
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static inline int quant_array_idx(const float val, const float *arr, const int num)
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{
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int i, index = 0;
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float quant_min_err = INFINITY;
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for (i = 0; i < num; i++) {
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float error = (val - arr[i])*(val - arr[i]);
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if (error < quant_min_err) {
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quant_min_err = error;
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index = i;
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}
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}
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return index;
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}
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/**
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* approximates exp10f(-3.0f*(0.5f + 0.5f * cosf(FFMIN(b,15.5f) / 15.5f)))
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*/
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static av_always_inline float bval2bmax(float b)
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{
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return 0.001f + 0.0035f * (b*b*b) / (15.5f*15.5f*15.5f);
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}
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/*
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* Compute a nextband map to be used with SF delta constraint utilities.
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* The nextband array should contain 128 elements, and positions that don't
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* map to valid, nonzero bands of the form w*16+g (with w being the initial
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* window of the window group, only) are left indetermined.
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*/
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static inline void ff_init_nextband_map(const SingleChannelElement *sce, uint8_t *nextband)
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{
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unsigned char prevband = 0;
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int w, g;
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/** Just a safe default */
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for (g = 0; g < 128; g++)
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nextband[g] = g;
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/** Now really navigate the nonzero band chain */
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for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
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for (g = 0; g < sce->ics.num_swb; g++) {
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if (!sce->zeroes[w*16+g] && sce->band_type[w*16+g] < RESERVED_BT)
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prevband = nextband[prevband] = w*16+g;
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}
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}
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nextband[prevband] = prevband; /* terminate */
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}
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/*
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* Updates nextband to reflect a removed band (equivalent to
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* calling ff_init_nextband_map after marking a band as zero)
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*/
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static inline void ff_nextband_remove(uint8_t *nextband, int prevband, int band)
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{
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nextband[prevband] = nextband[band];
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}
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/*
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* Checks whether the specified band could be removed without inducing
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* scalefactor delta that violates SF delta encoding constraints.
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* prev_sf has to be the scalefactor of the previous nonzero, nonspecial
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* band, in encoding order, or negative if there was no such band.
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*/
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static inline int ff_sfdelta_can_remove_band(const SingleChannelElement *sce,
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const uint8_t *nextband, int prev_sf, int band)
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{
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return prev_sf >= 0
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&& sce->sf_idx[nextband[band]] >= (prev_sf - SCALE_MAX_DIFF)
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&& sce->sf_idx[nextband[band]] <= (prev_sf + SCALE_MAX_DIFF);
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}
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/*
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* Checks whether the specified band's scalefactor could be replaced
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* with another one without violating SF delta encoding constraints.
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* prev_sf has to be the scalefactor of the previous nonzero, nonsepcial
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* band, in encoding order, or negative if there was no such band.
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*/
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static inline int ff_sfdelta_can_replace(const SingleChannelElement *sce,
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const uint8_t *nextband, int prev_sf, int new_sf, int band)
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{
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return new_sf >= (prev_sf - SCALE_MAX_DIFF)
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&& new_sf <= (prev_sf + SCALE_MAX_DIFF)
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&& sce->sf_idx[nextband[band]] >= (new_sf - SCALE_MAX_DIFF)
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&& sce->sf_idx[nextband[band]] <= (new_sf + SCALE_MAX_DIFF);
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}
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/**
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* linear congruential pseudorandom number generator
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*
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* @param previous_val pointer to the current state of the generator
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*
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* @return Returns a 32-bit pseudorandom integer
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*/
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static av_always_inline int lcg_random(unsigned previous_val)
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{
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union { unsigned u; int s; } v = { previous_val * 1664525u + 1013904223 };
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return v.s;
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}
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#define ERROR_IF(cond, ...) \
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if (cond) { \
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av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \
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return AVERROR(EINVAL); \
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}
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#define WARN_IF(cond, ...) \
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if (cond) { \
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av_log(avctx, AV_LOG_WARNING, __VA_ARGS__); \
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}
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#endif /* AVCODEC_AACENC_UTILS_H */
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