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Diffstat (limited to 'libavcodec/aacenc_utils.h')
| -rw-r--r-- | libavcodec/aacenc_utils.h | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/libavcodec/aacenc_utils.h b/libavcodec/aacenc_utils.h new file mode 100644 index 0000000000..bb1dcb4361 --- /dev/null +++ b/libavcodec/aacenc_utils.h @@ -0,0 +1,266 @@ +/* + * AAC encoder utilities + * Copyright (C) 2015 Rostislav Pehlivanov + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * AAC encoder utilities + * @author Rostislav Pehlivanov ( atomnuker gmail com ) + */ + +#ifndef AVCODEC_AACENC_UTILS_H +#define AVCODEC_AACENC_UTILS_H + +#include "libavutil/ffmath.h" +#include "aac.h" +#include "aacenctab.h" +#include "aactab.h" + +#define ROUND_STANDARD 0.4054f +#define ROUND_TO_ZERO 0.1054f +#define C_QUANT 0.4054f + +static inline void abs_pow34_v(float *out, const float *in, const int size) +{ + int i; + for (i = 0; i < size; i++) { + float a = fabsf(in[i]); + out[i] = sqrtf(a * sqrtf(a)); + } +} + +static inline float pos_pow34(float a) +{ + return sqrtf(a * sqrtf(a)); +} + +/** + * Quantize one coefficient. + * @return absolute value of the quantized coefficient + * @see 3GPP TS26.403 5.6.2 "Scalefactor determination" + */ +static inline int quant(float coef, const float Q, const float rounding) +{ + float a = coef * Q; + return sqrtf(a * sqrtf(a)) + rounding; +} + +static inline void quantize_bands(int *out, const float *in, const float *scaled, + int size, float Q34, int is_signed, int maxval, + const float rounding) +{ + int i; + for (i = 0; i < size; i++) { + float qc = scaled[i] * Q34; + int tmp = (int)FFMIN(qc + rounding, (float)maxval); + if (is_signed && in[i] < 0.0f) { + tmp = -tmp; + } + out[i] = tmp; + } +} + +static inline float find_max_val(int group_len, int swb_size, const float *scaled) +{ + float maxval = 0.0f; + int w2, i; + for (w2 = 0; w2 < group_len; w2++) { + for (i = 0; i < swb_size; i++) { + maxval = FFMAX(maxval, scaled[w2*128+i]); + } + } + return maxval; +} + +static inline int find_min_book(float maxval, int sf) +{ + float Q34 = ff_aac_pow34sf_tab[POW_SF2_ZERO - sf + SCALE_ONE_POS - SCALE_DIV_512]; + int qmaxval, cb; + qmaxval = maxval * Q34 + C_QUANT; + if (qmaxval >= (FF_ARRAY_ELEMS(aac_maxval_cb))) + cb = 11; + else + cb = aac_maxval_cb[qmaxval]; + return cb; +} + +static inline float find_form_factor(int group_len, int swb_size, float thresh, + const float *scaled, float nzslope) { + const float iswb_size = 1.0f / swb_size; + const float iswb_sizem1 = 1.0f / (swb_size - 1); + const float ethresh = thresh; + float form = 0.0f, weight = 0.0f; + int w2, i; + for (w2 = 0; w2 < group_len; w2++) { + float e = 0.0f, e2 = 0.0f, var = 0.0f, maxval = 0.0f; + float nzl = 0; + for (i = 0; i < swb_size; i++) { + float s = fabsf(scaled[w2*128+i]); + maxval = FFMAX(maxval, s); + e += s; + e2 += s *= s; + /* We really don't want a hard non-zero-line count, since + * even below-threshold lines do add up towards band spectral power. + * So, fall steeply towards zero, but smoothly + */ + if (s >= ethresh) { + nzl += 1.0f; + } else { + if (nzslope == 2.f) + nzl += (s / ethresh) * (s / ethresh); + else + nzl += ff_fast_powf(s / ethresh, nzslope); + } + } + if (e2 > thresh) { + float frm; + e *= iswb_size; + + /** compute variance */ + for (i = 0; i < swb_size; i++) { + float d = fabsf(scaled[w2*128+i]) - e; + var += d*d; + } + var = sqrtf(var * iswb_sizem1); + + e2 *= iswb_size; + frm = e / FFMIN(e+4*var,maxval); + form += e2 * sqrtf(frm) / FFMAX(0.5f,nzl); + weight += e2; + } + } + if (weight > 0) { + return form / weight; + } else { + return 1.0f; + } +} + +/** Return the minimum scalefactor where the quantized coef does not clip. */ +static inline uint8_t coef2minsf(float coef) +{ + return av_clip_uint8(log2f(coef)*4 - 69 + SCALE_ONE_POS - SCALE_DIV_512); +} + +/** Return the maximum scalefactor where the quantized coef is not zero. */ +static inline uint8_t coef2maxsf(float coef) +{ + return av_clip_uint8(log2f(coef)*4 + 6 + SCALE_ONE_POS - SCALE_DIV_512); +} + +/* + * Returns the closest possible index to an array of float values, given a value. + */ +static inline int quant_array_idx(const float val, const float *arr, const int num) +{ + int i, index = 0; + float quant_min_err = INFINITY; + for (i = 0; i < num; i++) { + float error = (val - arr[i])*(val - arr[i]); + if (error < quant_min_err) { + quant_min_err = error; + index = i; + } + } + return index; +} + +/** + * approximates exp10f(-3.0f*(0.5f + 0.5f * cosf(FFMIN(b,15.5f) / 15.5f))) + */ +static av_always_inline float bval2bmax(float b) +{ + return 0.001f + 0.0035f * (b*b*b) / (15.5f*15.5f*15.5f); +} + +/* + * Compute a nextband map to be used with SF delta constraint utilities. + * The nextband array should contain 128 elements, and positions that don't + * map to valid, nonzero bands of the form w*16+g (with w being the initial + * window of the window group, only) are left indetermined. + */ +static inline void ff_init_nextband_map(const SingleChannelElement *sce, uint8_t *nextband) +{ + unsigned char prevband = 0; + int w, g; + /** Just a safe default */ + for (g = 0; g < 128; g++) + nextband[g] = g; + + /** Now really navigate the nonzero band chain */ + for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { + for (g = 0; g < sce->ics.num_swb; g++) { + if (!sce->zeroes[w*16+g] && sce->band_type[w*16+g] < RESERVED_BT) + prevband = nextband[prevband] = w*16+g; + } + } + nextband[prevband] = prevband; /* terminate */ +} + +/* + * Updates nextband to reflect a removed band (equivalent to + * calling ff_init_nextband_map after marking a band as zero) + */ +static inline void ff_nextband_remove(uint8_t *nextband, int prevband, int band) +{ + nextband[prevband] = nextband[band]; +} + +/* + * Checks whether the specified band could be removed without inducing + * scalefactor delta that violates SF delta encoding constraints. + * prev_sf has to be the scalefactor of the previous nonzero, nonspecial + * band, in encoding order, or negative if there was no such band. + */ +static inline int ff_sfdelta_can_remove_band(const SingleChannelElement *sce, + const uint8_t *nextband, int prev_sf, int band) +{ + return prev_sf >= 0 + && sce->sf_idx[nextband[band]] >= (prev_sf - SCALE_MAX_DIFF) + && sce->sf_idx[nextband[band]] <= (prev_sf + SCALE_MAX_DIFF); +} + +/* + * Checks whether the specified band's scalefactor could be replaced + * with another one without violating SF delta encoding constraints. + * prev_sf has to be the scalefactor of the previous nonzero, nonsepcial + * band, in encoding order, or negative if there was no such band. + */ +static inline int ff_sfdelta_can_replace(const SingleChannelElement *sce, + const uint8_t *nextband, int prev_sf, int new_sf, int band) +{ + return new_sf >= (prev_sf - SCALE_MAX_DIFF) + && new_sf <= (prev_sf + SCALE_MAX_DIFF) + && sce->sf_idx[nextband[band]] >= (new_sf - SCALE_MAX_DIFF) + && sce->sf_idx[nextband[band]] <= (new_sf + SCALE_MAX_DIFF); +} + +#define ERROR_IF(cond, ...) \ + if (cond) { \ + av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \ + return AVERROR(EINVAL); \ + } + +#define WARN_IF(cond, ...) \ + if (cond) { \ + av_log(avctx, AV_LOG_WARNING, __VA_ARGS__); \ + } + +#endif /* AVCODEC_AACENC_UTILS_H */ |