| /* |
| * The simplest AC-3 encoder |
| * Copyright (c) 2000 Fabrice Bellard |
| * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com> |
| * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file |
| * floating-point AC-3 encoder. |
| */ |
| |
| #define AC3ENC_FLOAT 1 |
| #include "audiodsp.h" |
| #include "ac3enc.h" |
| #include "codec_internal.h" |
| #include "eac3enc.h" |
| #include "kbdwin.h" |
| |
| |
| /* |
| * Scale MDCT coefficients from float to 24-bit fixed-point. |
| */ |
| static void scale_coefficients(AC3EncodeContext *s) |
| { |
| int chan_size = AC3_MAX_COEFS * s->num_blocks; |
| int cpl = s->cpl_on; |
| s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl), |
| s->mdct_coef_buffer + (chan_size * !cpl), |
| chan_size * (s->channels + cpl)); |
| } |
| |
| |
| /* |
| * Clip MDCT coefficients to allowable range. |
| */ |
| static void clip_coefficients(AudioDSPContext *adsp, float *coef, |
| unsigned int len) |
| { |
| adsp->vector_clipf(coef, coef, len, COEF_MIN, COEF_MAX); |
| } |
| |
| |
| /* |
| * Calculate a single coupling coordinate. |
| */ |
| static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl) |
| { |
| float coord = 0.125; |
| if (energy_cpl > 0) |
| coord *= sqrtf(energy_ch / energy_cpl); |
| return FFMIN(coord, COEF_MAX); |
| } |
| |
| static void sum_square_butterfly(AC3EncodeContext *s, float sum[4], |
| const float *coef0, const float *coef1, |
| int len) |
| { |
| s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len); |
| } |
| |
| #include "ac3enc_template.c" |
| |
| /** |
| * Initialize MDCT tables. |
| * |
| * @param s AC-3 encoder private context |
| * @return 0 on success, negative error code on failure |
| */ |
| static av_cold int ac3_float_mdct_init(AC3EncodeContext *s) |
| { |
| const float scale = -2.0 / AC3_WINDOW_SIZE; |
| |
| ff_kbd_window_init(s->mdct_window_float, 5.0, AC3_BLOCK_SIZE); |
| |
| return av_tx_init(&s->tx, &s->tx_fn, AV_TX_FLOAT_MDCT, 0, |
| AC3_BLOCK_SIZE, &scale, 0); |
| } |
| |
| |
| av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx) |
| { |
| AC3EncodeContext *s = avctx->priv_data; |
| int ret; |
| |
| s->encode_frame = encode_frame; |
| s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT); |
| if (!s->fdsp) |
| return AVERROR(ENOMEM); |
| |
| ret = ac3_float_mdct_init(s); |
| if (ret < 0) |
| return ret; |
| |
| return ff_ac3_encode_init(avctx); |
| } |
| |
| const FFCodec ff_ac3_encoder = { |
| .p.name = "ac3", |
| CODEC_LONG_NAME("ATSC A/52A (AC-3)"), |
| .p.type = AVMEDIA_TYPE_AUDIO, |
| .p.id = AV_CODEC_ID_AC3, |
| .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE, |
| .priv_data_size = sizeof(AC3EncodeContext), |
| .init = ff_ac3_float_encode_init, |
| FF_CODEC_ENCODE_CB(ff_ac3_encode_frame), |
| .close = ff_ac3_encode_close, |
| .p.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP, |
| AV_SAMPLE_FMT_NONE }, |
| .p.priv_class = &ff_ac3enc_class, |
| .p.supported_samplerates = ff_ac3_sample_rate_tab, |
| .p.ch_layouts = ff_ac3_ch_layouts, |
| .defaults = ff_ac3_enc_defaults, |
| .caps_internal = FF_CODEC_CAP_INIT_CLEANUP, |
| }; |