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/* |
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* The simplest AC-3 encoder |
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* Copyright (c) 2000 Fabrice Bellard |
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* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com> |
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* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/** |
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* @file |
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* floating-point AC-3 encoder. |
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*/ |
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#define CONFIG_AC3ENC_FLOAT 1 |
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#include "internal.h" |
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#include "audiodsp.h" |
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#include "ac3enc.h" |
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#include "eac3enc.h" |
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#include "kbdwin.h" |
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#define AC3ENC_TYPE AC3ENC_TYPE_AC3 |
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#include "ac3enc_opts_template.c" |
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static const AVClass ac3enc_class = { |
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.class_name = "AC-3 Encoder", |
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.item_name = av_default_item_name, |
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.option = ac3_options, |
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.version = LIBAVUTIL_VERSION_INT, |
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}; |
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/* |
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* Scale MDCT coefficients from float to 24-bit fixed-point. |
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*/ |
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static void scale_coefficients(AC3EncodeContext *s) |
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{ |
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int chan_size = AC3_MAX_COEFS * s->num_blocks; |
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int cpl = s->cpl_on; |
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s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl), |
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s->mdct_coef_buffer + (chan_size * !cpl), |
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chan_size * (s->channels + cpl)); |
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} |
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/* |
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* Clip MDCT coefficients to allowable range. |
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*/ |
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static void clip_coefficients(AudioDSPContext *adsp, float *coef, |
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unsigned int len) |
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{ |
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adsp->vector_clipf(coef, coef, len, COEF_MIN, COEF_MAX); |
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} |
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/* |
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* Calculate a single coupling coordinate. |
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*/ |
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static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl) |
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{ |
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float coord = 0.125; |
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✓✗ |
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if (energy_cpl > 0) |
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coord *= sqrtf(energy_ch / energy_cpl); |
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✗✓ |
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return FFMIN(coord, COEF_MAX); |
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} |
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static void sum_square_butterfly(AC3EncodeContext *s, float sum[4], |
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const float *coef0, const float *coef1, |
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int len) |
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{ |
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s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len); |
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} |
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#include "ac3enc_template.c" |
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/** |
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* Finalize MDCT and free allocated memory. |
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* |
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* @param s AC-3 encoder private context |
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*/ |
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av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s) |
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{ |
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ff_mdct_end(&s->mdct); |
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av_freep(&s->mdct_window); |
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} |
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/** |
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* Initialize MDCT tables. |
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* |
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* @param s AC-3 encoder private context |
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* @return 0 on success, negative error code on failure |
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*/ |
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av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s) |
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{ |
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float *window; |
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int i, n, n2; |
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n = 1 << 9; |
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n2 = n >> 1; |
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window = av_malloc_array(n, sizeof(*window)); |
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✗✓ |
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if (!window) { |
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av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n"); |
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return AVERROR(ENOMEM); |
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} |
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ff_kbd_window_init(window, 5.0, n2); |
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✓✓ |
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for (i = 0; i < n2; i++) |
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window[n-1-i] = window[i]; |
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s->mdct_window = window; |
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return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n); |
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} |
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av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx) |
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{ |
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AC3EncodeContext *s = avctx->priv_data; |
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s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT); |
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✗✓ |
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if (!s->fdsp) |
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return AVERROR(ENOMEM); |
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return ff_ac3_encode_init(avctx); |
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} |
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AVCodec ff_ac3_encoder = { |
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.name = "ac3", |
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.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), |
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.type = AVMEDIA_TYPE_AUDIO, |
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.id = AV_CODEC_ID_AC3, |
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.priv_data_size = sizeof(AC3EncodeContext), |
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.init = ff_ac3_float_encode_init, |
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.encode2 = ff_ac3_float_encode_frame, |
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.close = ff_ac3_encode_close, |
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.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP, |
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AV_SAMPLE_FMT_NONE }, |
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.priv_class = &ac3enc_class, |
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.supported_samplerates = ff_ac3_sample_rate_tab, |
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.channel_layouts = ff_ac3_channel_layouts, |
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.defaults = ac3_defaults, |
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}; |