FFmpeg  4.4.4
ac3enc_float.c
Go to the documentation of this file.
1 /*
2  * The simplest AC-3 encoder
3  * Copyright (c) 2000 Fabrice Bellard
4  * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
5  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 /**
25  * @file
26  * floating-point AC-3 encoder.
27  */
28 
29 #define AC3ENC_FLOAT 1
30 #include "internal.h"
31 #include "audiodsp.h"
32 #include "ac3enc.h"
33 #include "eac3enc.h"
34 #include "kbdwin.h"
35 
36 
37 static const AVClass ac3enc_class = {
38  .class_name = "AC-3 Encoder",
39  .item_name = av_default_item_name,
40  .option = ff_ac3_enc_options,
41  .version = LIBAVUTIL_VERSION_INT,
42 };
43 
44 
45 /*
46  * Scale MDCT coefficients from float to 24-bit fixed-point.
47  */
49 {
50  int chan_size = AC3_MAX_COEFS * s->num_blocks;
51  int cpl = s->cpl_on;
52  s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
53  s->mdct_coef_buffer + (chan_size * !cpl),
54  chan_size * (s->channels + cpl));
55 }
56 
57 
58 /*
59  * Clip MDCT coefficients to allowable range.
60  */
61 static void clip_coefficients(AudioDSPContext *adsp, float *coef,
62  unsigned int len)
63 {
64  adsp->vector_clipf(coef, coef, len, COEF_MIN, COEF_MAX);
65 }
66 
67 
68 /*
69  * Calculate a single coupling coordinate.
70  */
71 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
72 {
73  float coord = 0.125;
74  if (energy_cpl > 0)
75  coord *= sqrtf(energy_ch / energy_cpl);
76  return FFMIN(coord, COEF_MAX);
77 }
78 
79 static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],
80  const float *coef0, const float *coef1,
81  int len)
82 {
83  s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);
84 }
85 
86 
87 #include "ac3enc_template.c"
88 
89 
90 /**
91  * Finalize MDCT and free allocated memory.
92  *
93  * @param s AC-3 encoder private context
94  */
96 {
97  ff_mdct_end(&s->mdct);
98 }
99 
100 
101 /**
102  * Initialize MDCT tables.
103  *
104  * @param s AC-3 encoder private context
105  * @return 0 on success, negative error code on failure
106  */
108 {
109  float *window = av_malloc_array(AC3_BLOCK_SIZE, sizeof(*window));
110  if (!window) {
111  av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
112  return AVERROR(ENOMEM);
113  }
114 
116  s->mdct_window = window;
117 
118  return ff_mdct_init(&s->mdct, 9, 0, -2.0 / AC3_WINDOW_SIZE);
119 }
120 
121 
123 {
124  AC3EncodeContext *s = avctx->priv_data;
125  s->mdct_end = ac3_float_mdct_end;
126  s->mdct_init = ac3_float_mdct_init;
127  s->allocate_sample_buffers = allocate_sample_buffers;
129  if (!s->fdsp)
130  return AVERROR(ENOMEM);
131  return ff_ac3_encode_init(avctx);
132 }
133 
135  .name = "ac3",
136  .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
137  .type = AVMEDIA_TYPE_AUDIO,
138  .id = AV_CODEC_ID_AC3,
139  .priv_data_size = sizeof(AC3EncodeContext),
141  .encode2 = ff_ac3_float_encode_frame,
142  .close = ff_ac3_encode_close,
143  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
145  .priv_class = &ac3enc_class,
146  .supported_samplerates = ff_ac3_sample_rate_tab,
147  .channel_layouts = ff_ac3_channel_layouts,
148  .defaults = ff_ac3_enc_defaults,
150 };
#define AC3_BLOCK_SIZE
Definition: ac3.h:35
#define AC3_WINDOW_SIZE
Definition: ac3.h:38
#define AC3_MAX_COEFS
Definition: ac3.h:34
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
Definition: ac3enc.c:2113
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
Definition: ac3enc.c:2506
const AVCodecDefault ff_ac3_enc_defaults[]
Definition: ac3enc.c:127
const AVOption ff_ac3_enc_options[]
Definition: ac3enc.c:77
const uint64_t ff_ac3_channel_layouts[19]
List of supported channel layouts.
Definition: ac3enc.c:142
AC-3 encoder & E-AC-3 encoder common header.
#define COEF_MAX
Definition: ac3enc.h:61
int ff_ac3_float_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
#define COEF_MIN
Definition: ac3enc.h:60
int64_t CoefSumType
Definition: ac3enc.h:65
int32_t CoefType
Definition: ac3enc.h:64
static void clip_coefficients(AudioDSPContext *adsp, float *coef, unsigned int len)
Definition: ac3enc_float.c:61
av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)
Definition: ac3enc_float.c:122
static av_cold int ac3_float_mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_float.c:107
static av_cold void ac3_float_mdct_end(AC3EncodeContext *s)
Finalize MDCT and free allocated memory.
Definition: ac3enc_float.c:95
AVCodec ff_ac3_encoder
Definition: ac3enc_float.c:134
static const AVClass ac3enc_class
Definition: ac3enc_float.c:37
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_float.c:48
static void sum_square_butterfly(AC3EncodeContext *s, float sum[4], const float *coef0, const float *coef1, int len)
Definition: ac3enc_float.c:79
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_float.c:71
AC-3 encoder float/fixed template.
static int allocate_sample_buffers(AC3EncodeContext *s)
const int ff_ac3_sample_rate_tab[]
Definition: ac3tab.c:111
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:925
#define av_cold
Definition: attributes.h:88
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
#define s(width, name)
Definition: cbs_vp9.c:257
#define FFMIN(a, b)
Definition: common.h:105
E-AC-3 encoder.
static SDL_Window * window
Definition: ffplay.c:366
#define ff_mdct_init
Definition: fft.h:161
#define ff_mdct_end
Definition: fft.h:162
#define AV_CODEC_FLAG_BITEXACT
Use only bitexact stuff (except (I)DCT).
Definition: avcodec.h:333
@ AV_CODEC_ID_AC3
Definition: codec_id.h:427
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
@ AV_SAMPLE_FMT_FLTP
float, planar
Definition: samplefmt.h:69
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:59
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
Generate a Kaiser-Bessel Derived Window.
Definition: kbdwin.c:26
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:49
av_cold AVFloatDSPContext * avpriv_float_dsp_alloc(int bit_exact)
Allocate a float DSP context.
Definition: float_dsp.c:135
common internal API header
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AC-3 encoder private context.
Definition: ac3enc.h:154
Describe the class of an AVClass context structure.
Definition: log.h:67
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
main external API structure.
Definition: avcodec.h:536
int flags
AV_CODEC_FLAG_*.
Definition: avcodec.h:616
void * priv_data
Definition: avcodec.h:563
AVCodec.
Definition: codec.h:197
const char * name
Name of the codec implementation.
Definition: codec.h:204
void(* vector_clipf)(float *dst, const float *src, int len, float min, float max)
Definition: audiodsp.h:49
#define av_malloc_array(a, b)
#define av_log(a,...)
int len