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120 lines
3.3 KiB
120 lines
3.3 KiB
/* |
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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 "ac3enc.h" |
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#include "eac3enc.h" |
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#include "kbdwin.h" |
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#if CONFIG_AC3_ENCODER |
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#define AC3ENC_TYPE AC3ENC_TYPE_AC3 |
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#include "ac3enc_opts_template.c" |
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static AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name, |
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ac3_options, LIBAVUTIL_VERSION_INT }; |
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#endif |
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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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av_cold void ff_ac3_float_mdct_end(AC3MDCTContext *mdct) |
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{ |
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ff_mdct_end(&mdct->fft); |
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av_freep(&mdct->window); |
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} |
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/** |
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* Initialize MDCT tables. |
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* @param nbits log2(MDCT size) |
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*/ |
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av_cold int ff_ac3_float_mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct, |
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int nbits) |
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{ |
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float *window; |
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int i, n, n2; |
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n = 1 << nbits; |
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n2 = n >> 1; |
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window = av_malloc(n * sizeof(*window)); |
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if (!window) { |
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av_log(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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for (i = 0; i < n2; i++) |
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window[n-1-i] = window[i]; |
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mdct->window = window; |
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return ff_mdct_init(&mdct->fft, nbits, 0, -2.0 / n); |
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} |
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/** |
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* Apply KBD window to input samples prior to MDCT. |
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*/ |
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void ff_ac3_float_apply_window(DSPContext *dsp, float *output, |
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const float *input, const float *window, |
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unsigned int len) |
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{ |
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dsp->vector_fmul(output, input, window, len); |
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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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void ff_ac3_float_scale_coefficients(AC3EncodeContext *s) |
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{ |
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int chan_size = AC3_MAX_COEFS * AC3_MAX_BLOCKS; |
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s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + chan_size, |
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s->mdct_coef_buffer + chan_size, |
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chan_size * s->channels); |
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} |
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#if CONFIG_AC3_ENCODER |
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AVCodec ff_ac3_float_encoder = { |
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"ac3_float", |
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AVMEDIA_TYPE_AUDIO, |
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CODEC_ID_AC3, |
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sizeof(AC3EncodeContext), |
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ff_ac3_encode_init, |
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ff_ac3_encode_frame, |
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ff_ac3_encode_close, |
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NULL, |
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.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE}, |
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.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), |
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.priv_class = &ac3enc_class, |
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.channel_layouts = ff_ac3_channel_layouts, |
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}; |
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#endif
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