xref: /third_party/ffmpeg/libavcodec/psymodel.c (revision cabdff1a) 
1/*
2 * audio encoder psychoacoustic model
3 * Copyright (C) 2008 Konstantin Shishkov
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <string.h>
23
24#include "avcodec.h"
25#include "psymodel.h"
26#include "iirfilter.h"
27#include "libavutil/mem.h"
28
29extern const FFPsyModel ff_aac_psy_model;
30
31av_cold int ff_psy_init(FFPsyContext *ctx, AVCodecContext *avctx, int num_lens,
32                        const uint8_t **bands, const int* num_bands,
33                        int num_groups, const uint8_t *group_map)
34{
35    int i, j, k = 0;
36
37    ctx->avctx = avctx;
38    ctx->ch        = av_calloc(avctx->ch_layout.nb_channels, 2 * sizeof(ctx->ch[0]));
39    ctx->group     = av_calloc(num_groups, sizeof(ctx->group[0]));
40    ctx->bands     = av_malloc_array (sizeof(ctx->bands[0]),      num_lens);
41    ctx->num_bands = av_malloc_array (sizeof(ctx->num_bands[0]),  num_lens);
42    ctx->cutoff    = avctx->cutoff;
43
44    if (!ctx->ch || !ctx->group || !ctx->bands || !ctx->num_bands) {
45        ff_psy_end(ctx);
46        return AVERROR(ENOMEM);
47    }
48
49    memcpy(ctx->bands,     bands,     sizeof(ctx->bands[0])     *  num_lens);
50    memcpy(ctx->num_bands, num_bands, sizeof(ctx->num_bands[0]) *  num_lens);
51
52    /* assign channels to groups (with virtual channels for coupling) */
53    for (i = 0; i < num_groups; i++) {
54        /* NOTE: Add 1 to handle the AAC chan_config without modification.
55         *       This has the side effect of allowing an array of 0s to map
56         *       to one channel per group.
57         */
58        ctx->group[i].num_ch = group_map[i] + 1;
59        for (j = 0; j < ctx->group[i].num_ch * 2; j++)
60            ctx->group[i].ch[j]  = &ctx->ch[k++];
61    }
62
63    switch (ctx->avctx->codec_id) {
64    case AV_CODEC_ID_AAC:
65        ctx->model = &ff_aac_psy_model;
66        break;
67    }
68    if (ctx->model->init)
69        return ctx->model->init(ctx);
70    return 0;
71}
72
73FFPsyChannelGroup *ff_psy_find_group(FFPsyContext *ctx, int channel)
74{
75    int i = 0, ch = 0;
76
77    while (ch <= channel)
78        ch += ctx->group[i++].num_ch;
79
80    return &ctx->group[i-1];
81}
82
83av_cold void ff_psy_end(FFPsyContext *ctx)
84{
85    if (ctx->model && ctx->model->end)
86        ctx->model->end(ctx);
87    av_freep(&ctx->bands);
88    av_freep(&ctx->num_bands);
89    av_freep(&ctx->group);
90    av_freep(&ctx->ch);
91}
92
93typedef struct FFPsyPreprocessContext{
94    AVCodecContext *avctx;
95    float stereo_att;
96    struct FFIIRFilterCoeffs *fcoeffs;
97    struct FFIIRFilterState **fstate;
98    struct FFIIRFilterContext fiir;
99}FFPsyPreprocessContext;
100
101#define FILT_ORDER 4
102
103av_cold struct FFPsyPreprocessContext* ff_psy_preprocess_init(AVCodecContext *avctx)
104{
105    FFPsyPreprocessContext *ctx;
106    int i;
107    float cutoff_coeff = 0;
108    ctx        = av_mallocz(sizeof(FFPsyPreprocessContext));
109    if (!ctx)
110        return NULL;
111    ctx->avctx = avctx;
112
113    /* AAC has its own LP method */
114    if (avctx->codec_id != AV_CODEC_ID_AAC) {
115        if (avctx->cutoff > 0)
116            cutoff_coeff = 2.0 * avctx->cutoff / avctx->sample_rate;
117
118        if (cutoff_coeff && cutoff_coeff < 0.98)
119        ctx->fcoeffs = ff_iir_filter_init_coeffs(avctx, FF_FILTER_TYPE_BUTTERWORTH,
120                                                 FF_FILTER_MODE_LOWPASS, FILT_ORDER,
121                                                 cutoff_coeff, 0.0, 0.0);
122        if (ctx->fcoeffs) {
123            ctx->fstate = av_calloc(avctx->ch_layout.nb_channels, sizeof(ctx->fstate[0]));
124            if (!ctx->fstate) {
125                av_free(ctx->fcoeffs);
126                av_free(ctx);
127                return NULL;
128            }
129            for (i = 0; i < avctx->ch_layout.nb_channels; i++)
130                ctx->fstate[i] = ff_iir_filter_init_state(FILT_ORDER);
131        }
132    }
133
134    ff_iir_filter_init(&ctx->fiir);
135
136    return ctx;
137}
138
139void ff_psy_preprocess(struct FFPsyPreprocessContext *ctx, float **audio, int channels)
140{
141    int ch;
142    int frame_size = ctx->avctx->frame_size;
143    FFIIRFilterContext *iir = &ctx->fiir;
144
145    if (ctx->fstate) {
146        for (ch = 0; ch < channels; ch++)
147            iir->filter_flt(ctx->fcoeffs, ctx->fstate[ch], frame_size,
148                            &audio[ch][frame_size], 1, &audio[ch][frame_size], 1);
149    }
150}
151
152av_cold void ff_psy_preprocess_end(struct FFPsyPreprocessContext *ctx)
153{
154    int i;
155    ff_iir_filter_free_coeffsp(&ctx->fcoeffs);
156    if (ctx->fstate)
157        for (i = 0; i < ctx->avctx->ch_layout.nb_channels; i++)
158            ff_iir_filter_free_statep(&ctx->fstate[i]);
159    av_freep(&ctx->fstate);
160    av_free(ctx);
161}
162