Libav
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 Libav.
8  *
9  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
29 #define 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 static const AVClass ac3enc_class = { "Fixed-Point AC-3 Encoder", av_default_item_name,
39 
40 #include "ac3enc_template.c"
41 
42 
49 {
50  ff_mdct_end(&s->mdct);
51 }
52 
53 
61 {
62  int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0);
63  s->mdct_window = ff_ac3_window;
64  return ret;
65 }
66 
67 
68 /*
69  * Normalize the input samples to use the maximum available precision.
70  * This assumes signed 16-bit input samples.
71  */
73 {
75  v = 14 - av_log2(v);
76  if (v > 0)
78  /* +6 to right-shift from 31-bit to 25-bit */
79  return v + 6;
80 }
81 
82 
83 /*
84  * Scale MDCT coefficients to 25-bit signed fixed-point.
85  */
87 {
88  int blk, ch;
89 
90  for (blk = 0; blk < s->num_blocks; blk++) {
91  AC3Block *block = &s->blocks[blk];
92  for (ch = 1; ch <= s->channels; ch++) {
94  block->coeff_shift[ch]);
95  }
96  }
97 }
98 
99 
100 /*
101  * Clip MDCT coefficients to allowable range.
102  */
103 static void clip_coefficients(DSPContext *dsp, int32_t *coef, unsigned int len)
104 {
105  dsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
106 }
107 
108 
109 /*
110  * Calculate a single coupling coordinate.
111  */
112 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
113 {
114  if (energy_cpl <= COEF_MAX) {
115  return 1048576;
116  } else {
117  uint64_t coord = energy_ch / (energy_cpl >> 24);
118  uint32_t coord32 = FFMIN(coord, 1073741824);
119  coord32 = ff_sqrt(coord32) << 9;
120  return FFMIN(coord32, COEF_MAX);
121  }
122 }
123 
124 
126 {
127  AC3EncodeContext *s = avctx->priv_data;
128  s->fixed_point = 1;
129  return ff_ac3_encode_init(avctx);
130 }
131 
132 
134  .name = "ac3_fixed",
135  .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
136  .type = AVMEDIA_TYPE_AUDIO,
137  .id = AV_CODEC_ID_AC3,
138  .priv_data_size = sizeof(AC3EncodeContext),
140  .encode2 = ff_ac3_fixed_encode_frame,
142  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16P,
144  .priv_class = &ac3enc_class,
145  .channel_layouts = ff_ac3_channel_layouts,
146  .defaults = ac3_defaults,
147 };
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
#define AC3_MAX_COEFS
Definition: ac3.h:34
static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
Definition: ac3enc_fixed.c:125
#define AC3_WINDOW_SIZE
Definition: ac3.h:38
#define COEF_MIN
Definition: ac3enc.h:64
#define blk(i)
Definition: sha.c:173
AVCodec.
Definition: avcodec.h:2755
DSPContext dsp
Definition: ac3enc.h:162
#define av_cold
Definition: attributes.h:66
av_cold int AC3_NAME() mdct_init(AC3EncodeContext *s)
Initialize MDCT tables.
Definition: ac3enc_fixed.c:60
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: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:48
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
sample_fmts
Definition: avconv_filter.c:68
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:142
#define AC3_NAME(x)
Definition: ac3enc.h:62
const char * name
Name of the codec implementation.
Definition: avcodec.h:2762
int fixed_point
indicates if fixed-point encoder is being used
Definition: ac3enc.h:170
#define ff_mdct_init
Definition: fft.h:144
Data for a single audio block.
Definition: ac3enc.h:128
#define FFMIN(a, b)
Definition: common.h:57
int32_t
LIBAVUTIL_VERSION_INT
Definition: eval.c:55
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:86
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_fixed.c:112
static av_const unsigned int ff_sqrt(unsigned int a)
Definition: mathops.h:207
AV_SAMPLE_FMT_NONE
Definition: avconv_filter.c:68
av_default_item_name
Definition: dnxhdenc.c:45
main external API structure.
Definition: avcodec.h:1054
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:489
Describe the class of an AVClass context structure.
Definition: log.h:33
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
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:103
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:287
#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:133
#define ff_mdct_end
Definition: fft.h:145
static const AVClass ac3enc_class
Definition: ac3enc_fixed.c:37
AVSampleFormat
Audio Sample Formats.
Definition: samplefmt.h:49
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[]
static av_cold int init(AVCodecParserContext *s)
Definition: h264_parser.c:498
AVCodecContext * avctx
parent AVCodecContext
Definition: ac3enc.h:160
void * priv_data
Definition: avcodec.h:1090
int len
#define av_log2
Definition: intmath.h:85
signed 16 bits, planar
Definition: samplefmt.h:58
static int normalize_samples(AC3EncodeContext *s)
Definition: ac3enc_fixed.c:72
AC-3 encoder & E-AC-3 encoder common header.
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:2421
static int16_t block[64]
Definition: dct-test.c:170