FFmpeg  2.1.1
ac3enc_fixed.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  * fixed-point AC-3 encoder.
27  */
28 
29 #define CONFIG_FFT_FLOAT 0
30 #undef CONFIG_AC3ENC_FLOAT
31 #include "internal.h"
32 #include "ac3enc.h"
33 #include "eac3enc.h"
34 
35 #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED
36 #include "ac3enc_opts_template.c"
37 
38 static const AVClass ac3enc_class = {
39  .class_name = "Fixed-Point AC-3 Encoder",
40  .item_name = av_default_item_name,
41  .option = ac3_options,
42  .version = LIBAVUTIL_VERSION_INT,
43 };
44 
45 #include "ac3enc_template.c"
46 
47 
48 /**
49  * Finalize MDCT and free allocated memory.
50  *
51  * @param s AC-3 encoder private context
52  */
54 {
55  ff_mdct_end(&s->mdct);
56 }
57 
58 
59 /**
60  * Initialize MDCT tables.
61  *
62  * @param s AC-3 encoder private context
63  * @return 0 on success, negative error code on failure
64  */
66 {
67  int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0);
68  s->mdct_window = ff_ac3_window;
69  return ret;
70 }
71 
72 
73 /*
74  * Apply KBD window to input samples prior to MDCT.
75  */
76 static void apply_window(void *dsp, int16_t *output, const int16_t *input,
77  const int16_t *window, unsigned int len)
78 {
79  DSPContext *dsp0 = dsp;
80  dsp0->apply_window_int16(output, input, window, len);
81 }
82 
83 
84 /*
85  * Normalize the input samples to use the maximum available precision.
86  * This assumes signed 16-bit input samples.
87  */
89 {
91  v = 14 - av_log2(v);
92  if (v > 0)
94  /* +6 to right-shift from 31-bit to 25-bit */
95  return v + 6;
96 }
97 
98 
99 /*
100  * Scale MDCT coefficients to 25-bit signed fixed-point.
101  */
103 {
104  int blk, ch;
105 
106  for (blk = 0; blk < s->num_blocks; blk++) {
107  AC3Block *block = &s->blocks[blk];
108  for (ch = 1; ch <= s->channels; ch++) {
110  block->coeff_shift[ch]);
111  }
112  }
113 }
114 
115 static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],
116  const int32_t *coef0, const int32_t *coef1,
117  int len)
118 {
119  s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);
120 }
121 
122 /*
123  * Clip MDCT coefficients to allowable range.
124  */
125 static void clip_coefficients(DSPContext *dsp, int32_t *coef, unsigned int len)
126 {
127  dsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
128 }
129 
130 
131 /*
132  * Calculate a single coupling coordinate.
133  */
134 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
135 {
136  if (energy_cpl <= COEF_MAX) {
137  return 1048576;
138  } else {
139  uint64_t coord = energy_ch / (energy_cpl >> 24);
140  uint32_t coord32 = FFMIN(coord, 1073741824);
141  coord32 = ff_sqrt(coord32) << 9;
142  return FFMIN(coord32, COEF_MAX);
143  }
144 }
145 
146 
148 {
149  AC3EncodeContext *s = avctx->priv_data;
150  s->fixed_point = 1;
151  return ff_ac3_encode_init(avctx);
152 }
153 
154 
156  .name = "ac3_fixed",
157  .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
158  .type = AVMEDIA_TYPE_AUDIO,
159  .id = AV_CODEC_ID_AC3,
160  .priv_data_size = sizeof(AC3EncodeContext),
162  .encode2 = ff_ac3_fixed_encode_frame,
164  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16P,
166  .priv_class = &ac3enc_class,
167  .channel_layouts = ff_ac3_channel_layouts,
168  .defaults = ac3_defaults,
169 };
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
float v
const char * s
Definition: avisynth_c.h:668
#define LIBAVUTIL_VERSION_INT
Definition: avcodec.h:820
#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:147
#define AC3_WINDOW_SIZE
Definition: ac3.h:38
#define COEF_MIN
Definition: ac3enc.h:64
void(* apply_window_int16)(int16_t *output, const int16_t *input, const int16_t *window, unsigned int len)
Apply symmetric window in 16-bit fixed-point.
Definition: dsputil.h:291
#define blk(i)
Definition: sha.c:185
AVCodec.
Definition: avcodec.h:2922
#define av_cold
Definition: avcodec.h:653
DSPContext dsp
Definition: ac3enc.h:162
const char * av_default_item_name(void *ctx)
Return the context name.
Definition: log.c:145
av_cold int AC3_NAME() mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_fixed.c:65
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:55
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
const char * name
Name of the codec implementation.
Definition: avcodec.h:2929
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
Definition: ac3enc.c:2014
const int16_t ff_ac3_window[AC3_WINDOW_SIZE/2]
Definition: ac3tab.c:151
AC3DSPContext ac3dsp
AC-3 optimized functions.
Definition: ac3enc.h:164
av_cold void AC3_NAME() mdct_end(AC3EncodeContext *s)
Finalize MDCT and free allocated memory.
Definition: ac3enc_fixed.c:53
int64_t CoefSumType
Definition: ac3enc.h:69
CoefType ** mdct_coef
MDCT coefficients.
Definition: ac3enc.h:129
const uint64_t ff_ac3_channel_layouts[19]
List of supported channel layouts.
Definition: ac3enc.c:78
int channels
total number of channels (nchans)
Definition: ac3enc.h:188
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:151
#define AC3_NAME(x)
Definition: ac3enc.h:62
int fixed_point
indicates if fixed-point encoder is being used
Definition: ac3enc.h:170
#define ff_mdct_init
Definition: fft.h:160
Data for a single audio block.
Definition: ac3enc.h:128
ret
Definition: avfilter.c:961
int32_t
#define FFMIN(a, b)
Definition: avcodec.h:925
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:102
AVSampleFormat
Audio Sample Formats.
Definition: samplefmt.h:49
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_fixed.c:134
static av_const unsigned int ff_sqrt(unsigned int a)
Definition: mathops.h:207
main external API structure.
Definition: avcodec.h:1146
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:538
Describe the class of an AVClass context structure.
Definition: log.h:50
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:157
AC3Block blocks[AC3_MAX_BLOCKS]
per-block info
Definition: ac3enc.h:168
SampleType * windowed_samples
Definition: ac3enc.h:230
static void apply_window(void *dsp, int16_t *output, const int16_t *input, const int16_t *window, unsigned int len)
Definition: ac3enc_fixed.c:76
void * priv_data
Definition: avcodec.h:1182
int num_blocks
number of blocks per frame
Definition: ac3enc.h:179
uint8_t coeff_shift[AC3_MAX_CHANNELS]
fixed-point coefficient shift values
Definition: ac3enc.h:139
static void clip_coefficients(DSPContext *dsp, int32_t *coef, unsigned int len)
Definition: ac3enc_fixed.c:125
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: dsputil.h:307
#define COEF_MAX
Definition: ac3enc.h:65
AC-3 encoder float/fixed template.
common internal api header.
AVCodec ff_ac3_fixed_encoder
Definition: ac3enc_fixed.c:155
#define ff_mdct_end
Definition: fft.h:161
static const AVClass ac3enc_class
Definition: ac3enc_fixed.c:38
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:160
int len
#define av_log2
Definition: intmath.h:89
static int normalize_samples(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:88
AC-3 encoder &amp; 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:700
signed 16 bits, planar
Definition: samplefmt.h:58
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:115
int32_t CoefType
Definition: ac3enc.h:68
E-AC-3 encoder.
DSPContext.
Definition: dsputil.h:124
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
Definition: ac3enc.c:2419
static int16_t block[64]
Definition: dct-test.c:198