/*

 * 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,

    CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP),

    .p.priv_class    = &ff_ac3enc_class,

    CODEC_SAMPLERATES_ARRAY(ff_ac3_sample_rate_tab),

    CODEC_CH_LAYOUTS_ARRAY(ff_ac3_ch_layouts),

    .defaults        = ff_ac3_enc_defaults,

    .caps_internal   = FF_CODEC_CAP_INIT_CLEANUP,

};