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
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  */
24 /**
25  * @file
26  * floating-point AC-3 encoder.
27  */
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"
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,
42 };
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 }
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 }
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 }
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 }
87 #include "ac3enc_template.c"
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 }
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  }
115  ff_kbd_window_init(window, 5.0, AC3_BLOCK_SIZE);
116  s->mdct_window = window;
118  return ff_mdct_init(&s->mdct, 9, 0, -2.0 / AC3_WINDOW_SIZE);
119 }
123 {
124  AC3EncodeContext *s = avctx->priv_data;
129  if (!s->fdsp)
130  return AVERROR(ENOMEM);
131  return ff_ac3_encode_init(avctx);
132 }
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 };
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:48
float, planar
Definition: samplefmt.h:69
void(* mdct_end)(struct AC3EncodeContext *s)
Definition: ac3enc.h:257
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
Generate a Kaiser-Bessel Derived Window.
Definition: kbdwin.c:26
Definition: version.h:85
static int allocate_sample_buffers(AC3EncodeContext *s)
const AVOption ff_ac3_enc_options[]
Definition: ac3enc.c:77
#define AC3_MAX_COEFS
Definition: ac3.h:35
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
Definition: ac3.h:39
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
#define COEF_MIN
Definition: ac3enc.h:60
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_float.c:71
int(* mdct_init)(struct AC3EncodeContext *s)
Definition: ac3enc.h:258
Definition: codec.h:190
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:79
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:40
#define av_cold
Definition: attributes.h:88
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
Definition: ac3enc.c:2113
void(* vector_clipf)(float *dst, const float *src, int len, float min, float max)
Definition: audiodsp.h:49
AVFixedDSPContext * fdsp
Definition: ac3enc.h:163
const AVCodecDefault ff_ac3_enc_defaults[]
Definition: ac3enc.c:127
AC3DSPContext ac3dsp
AC-3 optimized functions.
Definition: ac3enc.h:166
#define av_log(a,...)
av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)
Definition: ac3enc_float.c:122
int64_t CoefSumType
Definition: ac3enc.h:65
static const AVClass ac3enc_class
Definition: ac3enc_float.c:37
const uint64_t ff_ac3_channel_layouts[19]
List of supported channel layouts.
Definition: ac3enc.c:142
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
av_cold AVFloatDSPContext * avpriv_float_dsp_alloc(int bit_exact)
Allocate a float DSP context.
Definition: float_dsp.c:135
static av_cold void ac3_float_mdct_end(AC3EncodeContext *s)
Finalize MDCT and free allocated memory.
Definition: ac3enc_float.c:95
int channels
total number of channels (nchans)
Definition: ac3enc.h:190
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:115
int flags
Definition: avcodec.h:611
int cpl_on
coupling turned on for this frame
Definition: ac3enc.h:210
const char * name
Name of the codec implementation.
Definition: codec.h:197
#define ff_mdct_init
Definition: fft.h:161
AVCodec ff_ac3_encoder
Definition: ac3enc_float.c:134
#define AC3_BLOCK_SIZE
Definition: ac3.h:36
static SDL_Window * window
Definition: ffplay.c:366
Use only bitexact stuff (except (I)DCT).
Definition: avcodec.h:333
#define FFMIN(a, b)
Definition: common.h:105
AudioDSPContext adsp
Definition: ac3enc.h:159
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_float.c:48
#define s(width, name)
Definition: cbs_vp9.c:257
FFTContext mdct
FFT context for MDCT calculation.
Definition: ac3enc.h:167
const SampleType * mdct_window
MDCT window function array.
Definition: ac3enc.h:168
Audio sample formats.
Definition: samplefmt.h:58
main external API structure.
Definition: avcodec.h:531
CoefType * mdct_coef_buffer
Definition: ac3enc.h:236
int(* allocate_sample_buffers)(struct AC3EncodeContext *s)
Definition: ac3enc.h:261
Describe the class of an AVClass context structure.
Definition: log.h:67
AC-3 encoder private context.
Definition: ac3enc.h:154
int num_blocks
number of blocks per frame
Definition: ac3enc.h:181
#define COEF_MAX
Definition: ac3enc.h:61
static void clip_coefficients(AudioDSPContext *adsp, float *coef, unsigned int len)
Definition: ac3enc_float.c:61
AC-3 encoder float/fixed template.
common internal api header.
#define ff_mdct_end
Definition: fft.h:162
AVCodecContext * avctx
parent AVCodecContext
Definition: ac3enc.h:157
void * priv_data
Definition: avcodec.h:558
int len
static av_cold int ac3_float_mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_float.c:107
AC-3 encoder & E-AC-3 encoder common header.
void(* sum_square_butterfly_float)(float sum[4], const float *coef0, const float *coef1, int len)
Definition: ac3dsp.h:99
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:940
const int ff_ac3_sample_rate_tab[]
Definition: ac3tab.c:111
#define av_malloc_array(a, b)
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
int32_t CoefType
Definition: ac3enc.h:64
E-AC-3 encoder.
int32_t * fixed_coef_buffer
Definition: ac3enc.h:237
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:56
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
Definition: ac3enc.c:2506