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>
7 * This file is part of FFmpeg.
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.
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.
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
26 * floating-point AC-3 encoder.
29 #define CONFIG_AC3ENC_FLOAT 1
35 #if CONFIG_AC3_ENCODER
36 #define AC3ENC_TYPE AC3ENC_TYPE_AC3
37 #include "ac3enc_opts_template.c"
38 static AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,
39 ac3_options, LIBAVUTIL_VERSION_INT };
42 #include "ac3enc_template.c"
46 * Finalize MDCT and free allocated memory.
48 av_cold void ff_ac3_float_mdct_end(AC3MDCTContext *mdct)
50 ff_mdct_end(&mdct->fft);
51 av_freep(&mdct->window);
56 * Initialize MDCT tables.
57 * @param nbits log2(MDCT size)
59 av_cold int ff_ac3_float_mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
68 window = av_malloc(n * sizeof(*window));
70 av_log(avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
71 return AVERROR(ENOMEM);
73 ff_kbd_window_init(window, 5.0, n2);
74 for (i = 0; i < n2; i++)
75 window[n-1-i] = window[i];
76 mdct->window = window;
78 return ff_mdct_init(&mdct->fft, nbits, 0, -2.0 / n);
83 * Apply KBD window to input samples prior to MDCT.
85 void ff_ac3_float_apply_window(DSPContext *dsp, float *output,
86 const float *input, const float *window,
89 dsp->vector_fmul(output, input, window, len);
94 * Scale MDCT coefficients from float to 24-bit fixed-point.
96 void ff_ac3_float_scale_coefficients(AC3EncodeContext *s)
98 int chan_size = AC3_MAX_COEFS * AC3_MAX_BLOCKS;
99 s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + chan_size,
100 s->mdct_coef_buffer + chan_size,
101 chan_size * s->channels);
105 #if CONFIG_AC3_ENCODER
106 AVCodec ff_ac3_float_encoder = {
110 sizeof(AC3EncodeContext),
115 .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE},
116 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
117 .priv_class = &ac3enc_class,
118 .channel_layouts = ff_ac3_channel_layouts,