/* * 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 Libav. * * Libav 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. * * Libav 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 Libav; 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 CONFIG_AC3ENC_FLOAT 1 #include "internal.h" #include "ac3enc.h" #include "eac3enc.h" #include "kbdwin.h" #if CONFIG_AC3_ENCODER #define AC3ENC_TYPE AC3ENC_TYPE_AC3 #include "ac3enc_opts_template.c" static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name, ac3_options, LIBAVUTIL_VERSION_INT }; #endif #include "ac3enc_template.c" /** * Finalize MDCT and free allocated memory. * * @param s AC-3 encoder private context */ av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s) { ff_mdct_end(&s->mdct); av_freep(&s->mdct_window); } /** * Initialize MDCT tables. * * @param s AC-3 encoder private context * @return 0 on success, negative error code on failure */ av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s) { float *window; int i, n, n2; n = 1 << 9; n2 = n >> 1; window = av_malloc(n * sizeof(*window)); if (!window) { av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n"); return AVERROR(ENOMEM); } ff_kbd_window_init(window, 5.0, n2); for (i = 0; i < n2; i++) window[n-1-i] = window[i]; s->mdct_window = window; return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n); } /* * Apply KBD window to input samples prior to MDCT. */ static void apply_window(DSPContext *dsp, float *output, const float *input, const float *window, unsigned int len) { dsp->vector_fmul(output, input, window, len); } /* * Normalize the input samples. * Not needed for the floating-point encoder. */ static int normalize_samples(AC3EncodeContext *s) { return 0; } /* * 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(DSPContext *dsp, float *coef, unsigned int len) { dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len); } /* * 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); } #if CONFIG_AC3_ENCODER AVCodec ff_ac3_encoder = { .name = "ac3", .type = AVMEDIA_TYPE_AUDIO, .id = CODEC_ID_AC3, .priv_data_size = sizeof(AC3EncodeContext), .init = ff_ac3_encode_init, .encode2 = ff_ac3_float_encode_frame, .close = ff_ac3_encode_close, .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_NONE }, .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), .priv_class = &ac3enc_class, .channel_layouts = ff_ac3_channel_layouts, .defaults = ac3_defaults, }; #endif