FFmpeg
psymodel.c
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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 
29 extern const FFPsyModel ff_aac_psy_model;
30 
31 av_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_mallocz_array(sizeof(ctx->ch[0]), avctx->channels * 2);
39  ctx->group = av_mallocz_array(sizeof(ctx->group[0]), num_groups);
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 
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 
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 
93 typedef struct FFPsyPreprocessContext{
95  float stereo_att;
100 
101 #define FILT_ORDER 4
102 
104 {
106  int i;
107  float cutoff_coeff = 0;
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)
121  cutoff_coeff, 0.0, 0.0);
122  if (ctx->fcoeffs) {
123  ctx->fstate = av_mallocz_array(sizeof(ctx->fstate[0]), avctx->channels);
124  if (!ctx->fstate) {
125  av_free(ctx->fcoeffs);
126  av_free(ctx);
127  return NULL;
128  }
129  for (i = 0; i < avctx->channels; i++)
131  }
132  }
133 
134  ff_iir_filter_init(&ctx->fiir);
135 
136  return ctx;
137 }
138 
139 void 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 
153 {
154  int i;
155  ff_iir_filter_free_coeffsp(&ctx->fcoeffs);
156  if (ctx->fstate)
157  for (i = 0; i < ctx->avctx->channels; i++)
158  ff_iir_filter_free_statep(&ctx->fstate[i]);
159  av_freep(&ctx->fstate);
160  av_free(ctx);
161 }
FFIIRFilterState
IIR filter state.
Definition: iirfilter.c:47
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
iirfilter.h
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1098
FFPsyPreprocessContext::fcoeffs
struct FFIIRFilterCoeffs * fcoeffs
Definition: psymodel.c:96
av_mallocz_array
void * av_mallocz_array(size_t nmemb, size_t size)
Definition: mem.c:196
FFIIRFilterContext
Definition: iirfilter.h:51
FFIIRFilterContext::filter_flt
void(* filter_flt)(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state, int size, const float *src, ptrdiff_t sstep, float *dst, ptrdiff_t dstep)
Perform IIR filtering on floating-point input samples.
Definition: iirfilter.h:63
ff_psy_end
av_cold void ff_psy_end(FFPsyContext *ctx)
Cleanup model context at the end.
Definition: psymodel.c:83
FFIIRFilterCoeffs
IIR filter global parameters.
Definition: iirfilter.c:37
ff_aac_psy_model
const FFPsyModel ff_aac_psy_model
Definition: aacpsy.c:1019
av_cold
#define av_cold
Definition: attributes.h:90
frame_size
int frame_size
Definition: mxfenc.c:2206
ff_iir_filter_init
void ff_iir_filter_init(FFIIRFilterContext *f)
Initialize FFIIRFilterContext.
Definition: iirfilter.c:319
ctx
AVFormatContext * ctx
Definition: movenc.c:48
FILT_ORDER
#define FILT_ORDER
Definition: psymodel.c:101
channels
channels
Definition: aptx.h:33
bands
static const float bands[]
Definition: af_superequalizer.c:56
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:511
NULL
#define NULL
Definition: coverity.c:32
FF_FILTER_MODE_LOWPASS
@ FF_FILTER_MODE_LOWPASS
Definition: iirfilter.h:45
ff_iir_filter_init_coeffs
av_cold struct FFIIRFilterCoeffs * ff_iir_filter_init_coeffs(void *avc, enum IIRFilterType filt_type, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband, float ripple)
Initialize filter coefficients.
Definition: iirfilter.c:162
FFPsyPreprocessContext::avctx
AVCodecContext * avctx
Definition: psymodel.c:94
AV_CODEC_ID_AAC
@ AV_CODEC_ID_AAC
Definition: codec_id.h:422
FFPsyPreprocessContext
Definition: psymodel.c:93
AVCodecContext::channels
int channels
number of audio channels
Definition: avcodec.h:1099
ff_psy_init
av_cold int ff_psy_init(FFPsyContext *ctx, AVCodecContext *avctx, int num_lens, const uint8_t **bands, const int *num_bands, int num_groups, const uint8_t *group_map)
Initialize psychoacoustic model.
Definition: psymodel.c:31
i
int i
Definition: input.c:407
ff_iir_filter_free_coeffsp
av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp)
Free filter coefficients.
Definition: iirfilter.c:309
av_malloc_array
#define av_malloc_array(a, b)
Definition: tableprint_vlc.h:32
AVCodecContext::cutoff
int cutoff
Audio cutoff bandwidth (0 means "automatic")
Definition: avcodec.h:1142
FFPsyPreprocessContext::fiir
struct FFIIRFilterContext fiir
Definition: psymodel.c:98
ff_psy_preprocess_init
av_cold struct FFPsyPreprocessContext * ff_psy_preprocess_init(AVCodecContext *avctx)
psychoacoustic model audio preprocessing initialization
Definition: psymodel.c:103
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:243
FFPsyPreprocessContext::fstate
struct FFIIRFilterState ** fstate
Definition: psymodel.c:97
avcodec.h
FFPsyChannelGroup
psychoacoustic information for an arbitrary group of channels
Definition: psymodel.h:68
ff_iir_filter_init_state
av_cold struct FFIIRFilterState * ff_iir_filter_init_state(int order)
Create new filter state.
Definition: iirfilter.c:201
ff_psy_preprocess
void ff_psy_preprocess(struct FFPsyPreprocessContext *ctx, float **audio, int channels)
Preprocess several channel in audio frame in order to compress it better.
Definition: psymodel.c:139
AVCodecContext
main external API structure.
Definition: avcodec.h:501
FFPsyModel
codec-specific psychoacoustic model implementation
Definition: psymodel.h:114
ff_psy_find_group
FFPsyChannelGroup * ff_psy_find_group(FFPsyContext *ctx, int channel)
Determine what group a channel belongs to.
Definition: psymodel.c:73
mem.h
ff_iir_filter_free_statep
av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state)
Free and zero filter state.
Definition: iirfilter.c:304
FF_FILTER_TYPE_BUTTERWORTH
@ FF_FILTER_TYPE_BUTTERWORTH
Definition: iirfilter.h:39
FFPsyPreprocessContext::stereo_att
float stereo_att
Definition: psymodel.c:95
av_free
#define av_free(p)
Definition: tableprint_vlc.h:34
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
ff_psy_preprocess_end
av_cold void ff_psy_preprocess_end(struct FFPsyPreprocessContext *ctx)
Cleanup audio preprocessing module.
Definition: psymodel.c:152
FFPsyContext
context used by psychoacoustic model
Definition: psymodel.h:89
psymodel.h
channel
channel
Definition: ebur128.h:39