598c69db1b68272b12e99ede21025ed254c07601
[libav.git] / libavcodec / ac3enc_float.c
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
24 /**
25 * @file
26 * floating-point AC-3 encoder.
27 */
28
29 #define CONFIG_AC3ENC_FLOAT 1
30 #include "ac3enc.h"
31 #include "eac3enc.h"
32 #include "kbdwin.h"
33
34
35 #if CONFIG_AC3_ENCODER
36 #define AC3ENC_TYPE AC3ENC_TYPE_AC3
37 #include "ac3enc_opts_template.c"
38 static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,
39 ac3_options, LIBAVUTIL_VERSION_INT };
40 #endif
41
42 #include "ac3enc_template.c"
43
44
45 /**
46 * Finalize MDCT and free allocated memory.
47 */
48 av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
49 {
50 ff_mdct_end(&s->mdct);
51 av_freep(&s->mdct_window);
52 }
53
54
55 /**
56 * Initialize MDCT tables.
57 * @param nbits log2(MDCT size)
58 */
59 av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
60 {
61 float *window;
62 int i, n, n2;
63
64 n = 1 << 9;
65 n2 = n >> 1;
66
67 window = av_malloc(n * sizeof(*window));
68 if (!window) {
69 av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
70 return AVERROR(ENOMEM);
71 }
72 ff_kbd_window_init(window, 5.0, n2);
73 for (i = 0; i < n2; i++)
74 window[n-1-i] = window[i];
75 s->mdct_window = window;
76
77 return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
78 }
79
80
81 /**
82 * Apply KBD window to input samples prior to MDCT.
83 */
84 static void apply_window(DSPContext *dsp, float *output, const float *input,
85 const float *window, unsigned int len)
86 {
87 dsp->vector_fmul(output, input, window, len);
88 }
89
90
91 /**
92 * Normalize the input samples.
93 * Not needed for the floating-point encoder.
94 */
95 static int normalize_samples(AC3EncodeContext *s)
96 {
97 return 0;
98 }
99
100
101 /**
102 * Scale MDCT coefficients from float to 24-bit fixed-point.
103 */
104 static void scale_coefficients(AC3EncodeContext *s)
105 {
106 int chan_size = AC3_MAX_COEFS * s->num_blocks;
107 int cpl = s->cpl_on;
108 s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
109 s->mdct_coef_buffer + (chan_size * !cpl),
110 chan_size * (s->channels + cpl));
111 }
112
113
114 /**
115 * Clip MDCT coefficients to allowable range.
116 */
117 static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)
118 {
119 dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
120 }
121
122
123 /**
124 * Calculate a single coupling coordinate.
125 */
126 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
127 {
128 float coord = 0.125;
129 if (energy_cpl > 0)
130 coord *= sqrtf(energy_ch / energy_cpl);
131 return FFMIN(coord, COEF_MAX);
132 }
133
134
135 #if CONFIG_AC3_ENCODER
136 AVCodec ff_ac3_encoder = {
137 .name = "ac3",
138 .type = AVMEDIA_TYPE_AUDIO,
139 .id = CODEC_ID_AC3,
140 .priv_data_size = sizeof(AC3EncodeContext),
141 .init = ff_ac3_encode_init,
142 .encode = ff_ac3_float_encode_frame,
143 .close = ff_ac3_encode_close,
144 .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE},
145 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
146 .priv_class = &ac3enc_class,
147 .channel_layouts = ff_ac3_channel_layouts,
148 };
149 #endif