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ac3enc_fixed.c
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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  * fixed-point AC-3 encoder.
27  */
28 
29 #define FFT_FLOAT 0
30 #undef CONFIG_AC3ENC_FLOAT
31 #include "internal.h"
32 #include "audiodsp.h"
33 #include "ac3enc.h"
34 #include "eac3enc.h"
35 
36 #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED
37 #include "ac3enc_opts_template.c"
38 
39 static const AVClass ac3enc_class = {
40  .class_name = "Fixed-Point 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 }
58 
59 
60 /**
61  * Initialize MDCT tables.
62  *
63  * @param s AC-3 encoder private context
64  * @return 0 on success, negative error code on failure
65  */
67 {
68  int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0);
69  s->mdct_window = ff_ac3_window;
70  return ret;
71 }
72 
73 
74 /*
75  * Normalize the input samples to use the maximum available precision.
76  * This assumes signed 16-bit input samples.
77  */
79 {
81  v = 14 - av_log2(v);
82  if (v > 0)
84  /* +6 to right-shift from 31-bit to 25-bit */
85  return v + 6;
86 }
87 
88 
89 /*
90  * Scale MDCT coefficients to 25-bit signed fixed-point.
91  */
93 {
94  int blk, ch;
95 
96  for (blk = 0; blk < s->num_blocks; blk++) {
97  AC3Block *block = &s->blocks[blk];
98  for (ch = 1; ch <= s->channels; ch++) {
100  block->coeff_shift[ch]);
101  }
102  }
103 }
104 
105 static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],
106  const int32_t *coef0, const int32_t *coef1,
107  int len)
108 {
109  s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);
110 }
111 
112 /*
113  * Clip MDCT coefficients to allowable range.
114  */
116  unsigned int len)
117 {
118  adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
119 }
120 
121 
122 /*
123  * Calculate a single coupling coordinate.
124  */
125 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
126 {
127  if (energy_cpl <= COEF_MAX) {
128  return 1048576;
129  } else {
130  uint64_t coord = energy_ch / (energy_cpl >> 24);
131  uint32_t coord32 = FFMIN(coord, 1073741824);
132  coord32 = ff_sqrt(coord32) << 9;
133  return FFMIN(coord32, COEF_MAX);
134  }
135 }
136 
137 
139 {
140  AC3EncodeContext *s = avctx->priv_data;
141  s->fixed_point = 1;
142  return ff_ac3_encode_init(avctx);
143 }
144 
145 
147  .name = "ac3_fixed",
148  .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
149  .type = AVMEDIA_TYPE_AUDIO,
150  .id = AV_CODEC_ID_AC3,
151  .priv_data_size = sizeof(AC3EncodeContext),
153  .encode2 = ff_ac3_fixed_encode_frame,
154  .close = ff_ac3_encode_close,
155  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16P,
157  .priv_class = &ac3enc_class,
158  .channel_layouts = ff_ac3_channel_layouts,
159  .defaults = ac3_defaults,
160 };
void(* ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift)
Right-shift each value in an array of int32_t by a specified amount.
Definition: ac3dsp.h:76
void(* vector_clip_int32)(int32_t *dst, const int32_t *src, int32_t min, int32_t max, unsigned int len)
Clip each element in an array of int32_t to a given minimum and maximum value.
Definition: audiodsp.h:46
const char * s
Definition: avisynth_c.h:631
#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
static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
Definition: ac3enc_fixed.c:138
#define AC3_WINDOW_SIZE
Definition: ac3.h:38
int av_log2(unsigned v)
Definition: intmath.c:26
#define COEF_MIN
Definition: ac3enc.h:67
#define blk(i)
Definition: sha.c:185
AVCodec.
Definition: avcodec.h:3559
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
#define av_cold
Definition: attributes.h:82
av_cold int AC3_NAME() mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_fixed.c:66
int(* ac3_max_msb_abs_int16)(const int16_t *src, int len)
Calculate the maximum MSB of the absolute value of each element in an array of int16_t.
Definition: ac3dsp.h:54
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
Definition: ac3enc.c:2017
const int16_t ff_ac3_window[AC3_WINDOW_SIZE/2]
Definition: ac3tab.c:153
AC3DSPContext ac3dsp
AC-3 optimized functions.
Definition: ac3enc.h:170
av_cold void AC3_NAME() mdct_end(AC3EncodeContext *s)
Finalize MDCT and free allocated memory.
Definition: ac3enc_fixed.c:54
#define ff_sqrt
Definition: mathops.h:215
int64_t CoefSumType
Definition: ac3enc.h:72
CoefType ** mdct_coef
MDCT coefficients.
Definition: ac3enc.h:134
const uint64_t ff_ac3_channel_layouts[19]
List of supported channel layouts.
Definition: ac3enc.c:81
av_default_item_name
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
#define AC3_NAME(x)
Definition: ac3enc.h:65
const char * name
Name of the codec implementation.
Definition: avcodec.h:3566
int fixed_point
indicates if fixed-point encoder is being used
Definition: ac3enc.h:176
#define ff_mdct_init
Definition: fft.h:169
Data for a single audio block.
Definition: ac3enc.h:133
#define FFMIN(a, b)
Definition: common.h:96
AudioDSPContext adsp
Definition: ac3enc.h:167
int32_t
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:92
static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef, unsigned int len)
Definition: ac3enc_fixed.c:115
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_fixed.c:125
main external API structure.
Definition: avcodec.h:1657
Describe the class of an AVClass context structure.
Definition: log.h:67
int ff_ac3_fixed_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
static const AVCodecDefault ac3_defaults[]
AC-3 encoder private context.
Definition: ac3enc.h:162
AC3Block blocks[AC3_MAX_BLOCKS]
per-block info
Definition: ac3enc.h:174
SampleType * windowed_samples
Definition: ac3enc.h:236
int num_blocks
number of blocks per frame
Definition: ac3enc.h:185
uint8_t coeff_shift[AC3_MAX_CHANNELS]
fixed-point coefficient shift values
Definition: ac3enc.h:144
#define COEF_MAX
Definition: ac3enc.h:68
AC-3 encoder float/fixed template.
common internal api header.
AVCodec ff_ac3_fixed_encoder
Definition: ac3enc_fixed.c:146
#define ff_mdct_end
Definition: fft.h:170
static const AVClass ac3enc_class
Definition: ac3enc_fixed.c:39
void(* ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift)
Left-shift each value in an array of int16_t by a specified amount.
Definition: ac3dsp.h:65
static const AVOption ac3_options[]
AVCodecContext * avctx
parent AVCodecContext
Definition: ac3enc.h:165
void * priv_data
Definition: avcodec.h:1699
int len
static int normalize_samples(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:78
AC-3 encoder & E-AC-3 encoder common header.
void(* sum_square_butterfly_int32)(int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)
Definition: ac3dsp.h:129
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
signed 16 bits, planar
Definition: samplefmt.h:67
static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)
Definition: ac3enc_fixed.c:105
int32_t CoefType
Definition: ac3enc.h:71
E-AC-3 encoder.
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
Definition: ac3enc.c:2425
static int16_t block[64]
Definition: dct-test.c:112