FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
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 CONFIG_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 #define AC3ENC_TYPE AC3ENC_TYPE_AC3
38 #include "ac3enc_opts_template.c"
39 static const AVClass ac3enc_class = {
40  .class_name = "AC-3 Encoder",
41  .item_name = av_default_item_name,
42  .option = ac3_options,
43  .version = LIBAVUTIL_VERSION_INT,
44 };
45 
46 #include "ac3enc_template.c"
47 
48 
49 /**
50  * Finalize MDCT and free allocated memory.
51  *
52  * @param s AC-3 encoder private context
53  */
55 {
56  ff_mdct_end(&s->mdct);
57  av_freep(&s->mdct_window);
58 }
59 
60 
61 /**
62  * Initialize MDCT tables.
63  *
64  * @param s AC-3 encoder private context
65  * @return 0 on success, negative error code on failure
66  */
68 {
69  float *window;
70  int i, n, n2;
71 
72  n = 1 << 9;
73  n2 = n >> 1;
74 
75  window = av_malloc_array(n, sizeof(*window));
76  if (!window) {
77  av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
78  return AVERROR(ENOMEM);
79  }
80  ff_kbd_window_init(window, 5.0, n2);
81  for (i = 0; i < n2; i++)
82  window[n-1-i] = window[i];
83  s->mdct_window = window;
84 
85  return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
86 }
87 
88 
89 /*
90  * Normalize the input samples.
91  * Not needed for the floating-point encoder.
92  */
94 {
95  return 0;
96 }
97 
98 
99 /*
100  * Scale MDCT coefficients from float to 24-bit fixed-point.
101  */
103 {
104  int chan_size = AC3_MAX_COEFS * s->num_blocks;
105  int cpl = s->cpl_on;
106  s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
107  s->mdct_coef_buffer + (chan_size * !cpl),
108  chan_size * (s->channels + cpl));
109 }
110 
111 static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],
112  const float *coef0, const float *coef1,
113  int len)
114 {
115  s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);
116 }
117 
118 /*
119  * Clip MDCT coefficients to allowable range.
120  */
121 static void clip_coefficients(AudioDSPContext *adsp, float *coef,
122  unsigned int len)
123 {
124  adsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
125 }
126 
127 
128 /*
129  * Calculate a single coupling coordinate.
130  */
131 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
132 {
133  float coord = 0.125;
134  if (energy_cpl > 0)
135  coord *= sqrtf(energy_ch / energy_cpl);
136  return FFMIN(coord, COEF_MAX);
137 }
138 
140 {
141  AC3EncodeContext *s = avctx->priv_data;
143  if (!s->fdsp)
144  return AVERROR(ENOMEM);
145  return ff_ac3_encode_init(avctx);
146 }
147 
149  .name = "ac3",
150  .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
151  .type = AVMEDIA_TYPE_AUDIO,
152  .id = AV_CODEC_ID_AC3,
153  .priv_data_size = sizeof(AC3EncodeContext),
155  .encode2 = ff_ac3_float_encode_frame,
156  .close = ff_ac3_encode_close,
157  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
159  .priv_class = &ac3enc_class,
160  .channel_layouts = ff_ac3_channel_layouts,
161  .defaults = ac3_defaults,
162 };
float, planar
Definition: samplefmt.h:69
const char * s
Definition: avisynth_c.h:631
AVFloatDSPContext * fdsp
Definition: ac3enc.h:168
void(* float_to_fixed24)(int32_t *dst, const float *src, unsigned int len)
Convert an array of float in range [-1.0,1.0] to int32_t with range [-(1<<24),(1<<24)].
Definition: ac3dsp.h:89
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
Generate a Kaiser-Bessel Derived Window.
Definition: kbdwin.c:26
#define LIBAVUTIL_VERSION_INT
Definition: version.h:70
#define AC3_MAX_COEFS
Definition: ac3.h:34
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
void(* sum_square_butterfly_float)(float sum[4], const float *coef0, const float *coef1, int len)
Definition: ac3dsp.h:132
#define COEF_MIN
Definition: ac3enc.h:67
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_float.c:131
AVCodec.
Definition: avcodec.h:3559
int ff_ac3_float_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
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
static void sum_square_butterfly(AC3EncodeContext *s, float sum[4], const float *coef0, const float *coef1, int len)
Definition: ac3enc_float.c:111
#define av_cold
Definition: attributes.h:82
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
Definition: ac3enc.c:2017
av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_float.c:67
AC3DSPContext ac3dsp
AC-3 optimized functions.
Definition: ac3enc.h:170
#define av_log(a,...)
av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)
Definition: ac3enc_float.c:139
int64_t CoefSumType
Definition: ac3enc.h:72
static int normalize_samples(AC3EncodeContext *s)
Definition: ac3enc_float.c:93
static const AVClass ac3enc_class
Definition: ac3enc_float.c:39
const uint64_t ff_ac3_channel_layouts[19]
List of supported channel layouts.
Definition: ac3enc.c:81
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
av_default_item_name
#define AVERROR(e)
Definition: error.h:43
int channels
total number of channels (nchans)
Definition: ac3enc.h:194
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
int flags
AV_CODEC_FLAG_*.
Definition: avcodec.h:1752
int cpl_on
coupling turned on for this frame
Definition: ac3enc.h:214
const char * name
Name of the codec implementation.
Definition: avcodec.h:3566
#define ff_mdct_init
Definition: fft.h:169
AVCodec ff_ac3_encoder
Definition: ac3enc_float.c:148
#define AV_CODEC_FLAG_BITEXACT
Use only bitexact stuff (except (I)DCT).
Definition: avcodec.h:883
#define FFMIN(a, b)
Definition: common.h:96
AudioDSPContext adsp
Definition: ac3enc.h:167
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_float.c:102
int n
Definition: avisynth_c.h:547
FFTContext mdct
FFT context for MDCT calculation.
Definition: ac3enc.h:171
const SampleType * mdct_window
MDCT window function array.
Definition: ac3enc.h:172
void(* vector_clipf)(float *dst, const float *src, float min, float max, int len)
Definition: audiodsp.h:49
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
main external API structure.
Definition: avcodec.h:1657
CoefType * mdct_coef_buffer
Definition: ac3enc.h:240
Describe the class of an AVClass context structure.
Definition: log.h:67
static const AVCodecDefault ac3_defaults[]
AC-3 encoder private context.
Definition: ac3enc.h:162
av_cold AVFloatDSPContext * avpriv_float_dsp_alloc(int bit_exact)
Allocate a float DSP context.
Definition: float_dsp.c:119
int num_blocks
number of blocks per frame
Definition: ac3enc.h:185
#define COEF_MAX
Definition: ac3enc.h:68
static void clip_coefficients(AudioDSPContext *adsp, float *coef, unsigned int len)
Definition: ac3enc_float.c:121
AC-3 encoder float/fixed template.
common internal api header.
#define ff_mdct_end
Definition: fft.h:170
static const AVOption ac3_options[]
AVCodecContext * avctx
parent AVCodecContext
Definition: ac3enc.h:165
void * priv_data
Definition: avcodec.h:1699
int len
AC-3 encoder & E-AC-3 encoder common header.
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
#define av_freep(p)
#define av_malloc_array(a, b)
int32_t CoefType
Definition: ac3enc.h:71
E-AC-3 encoder.
av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
Finalize MDCT and free allocated memory.
Definition: ac3enc_float.c:54
int32_t * fixed_coef_buffer
Definition: ac3enc.h:241
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
Definition: ac3enc.c:2425