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/*

 * Copyright (c) CMU 1993 Computer Science, Speech Group

 *                        Chengxiang Lu and Alex Hauptmann

 * Copyright (c) 2005 Steve Underwood 

 * Copyright (c) 2009 Kenan Gillet

 * Copyright (c) 2010 Martin Storsjo

 *

 * 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

 * G.722 ADPCM audio decoder

 *

 * This G.722 decoder is a bit-exact implementation of the ITU G.722

 * specification for all three specified bitrates - 64000bps, 56000bps

 * and 48000bps. It passes the ITU tests.

 *

 * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits

 *       respectively of each byte are ignored.

 */

#include "libavutil/channel_layout.h"

#include "libavutil/opt.h"

#include "avcodec.h"

#include "get_bits.h"

#include "g722.h"

#include "internal.h"

#define OFFSET(x) offsetof(G722Context, x)

#define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {

    { "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_FLAGS, { .i64 = 8 }, 6, 8, AD },

    { NULL }

};

static const AVClass g722_decoder_class = {

    .class_name = "g722 decoder",

    .item_name  = av_default_item_name,

    .option     = options,

    .version    = LIBAVUTIL_VERSION_INT,

};

static av_cold int g722_decode_init(AVCodecContext * avctx)

{

    G722Context *c = avctx->priv_data;

    avctx->channels       = 1;

    avctx->channel_layout = AV_CH_LAYOUT_MONO;

    avctx->sample_fmt     = AV_SAMPLE_FMT_S16;

    c->band[0].scale_factor = 8;

    c->band[1].scale_factor = 2;

    c->prev_samples_pos = 22;

    return 0;

}

static const int16_t low_inv_quant5[32] = {

     -35,   -35, -2919, -2195, -1765, -1458, -1219, -1023,

    -858,  -714,  -587,  -473,  -370,  -276,  -190,  -110,

    2919,  2195,  1765,  1458,  1219,  1023,   858,   714,

     587,   473,   370,   276,   190,   110,    35,   -35

};

static const int16_t *low_inv_quants[3] = { ff_g722_low_inv_quant6,

                                                    low_inv_quant5,

                                            ff_g722_low_inv_quant4 };

static int g722_decode_frame(AVCodecContext *avctx, void *data,

                             int *got_frame_ptr, AVPacket *avpkt)

{

    G722Context *c = avctx->priv_data;

    AVFrame *frame = data;

    int16_t *out_buf;

    int j, ret;

    const int skip = 8 - c->bits_per_codeword;

    const int16_t *quantizer_table = low_inv_quants[skip];

    GetBitContext gb;

    /* get output buffer */

    frame->nb_samples = avpkt->size * 2;

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

        return ret;

    out_buf = (int16_t *)frame->data[0];

    init_get_bits(&gb, avpkt->data, avpkt->size * 8);

    for (j = 0; j < avpkt->size; j++) {

        int ilow, ihigh, rlow, rhigh, dhigh;

        int xout1, xout2;

        ihigh = get_bits(&gb, 2);

        ilow = get_bits(&gb, 6 - skip);

        skip_bits(&gb, skip);

        rlow = av_clip((c->band[0].scale_factor * quantizer_table[ilow] >> 10)

                      + c->band[0].s_predictor, -16384, 16383);

        ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));

        dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;

        rhigh = av_clip(dhigh + c->band[1].s_predictor, -16384, 16383);

        ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);

        c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;

        c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;

        ff_g722_apply_qmf(c->prev_samples + c->prev_samples_pos - 24,

                          &xout1, &xout2);

        *out_buf++ = av_clip_int16(xout1 >> 11);

        *out_buf++ = av_clip_int16(xout2 >> 11);

        if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {

            memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,

                    22 * sizeof(c->prev_samples[0]));

            c->prev_samples_pos = 22;

        }

    }

    *got_frame_ptr = 1;

    return avpkt->size;

}

AVCodec ff_adpcm_g722_decoder = {

    .name           = "g722",

    .long_name      = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),

    .type           = AVMEDIA_TYPE_AUDIO,

    .id             = AV_CODEC_ID_ADPCM_G722,

    .priv_data_size = sizeof(G722Context),

    .init           = g722_decode_init,

    .decode         = g722_decode_frame,

    .capabilities   = CODEC_CAP_DR1,

    .priv_class     = &g722_decoder_class,

};