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/*

 * ADX ADPCM codecs

 * Copyright (c) 2001,2003 BERO

 *

 * 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

 */

#include "libavutil/intreadwrite.h"

#include "avcodec.h"

#include "adx.h"

#include "get_bits.h"

#include "internal.h"

/**

 * @file

 * SEGA CRI adx codecs.

 *

 * Reference documents:

 * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html

 * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/

 */

static av_cold int adx_decode_init(AVCodecContext *avctx)

{

    ADXContext *c = avctx->priv_data;

    int ret, header_size;

    if (avctx->extradata_size >= 24) {

        if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,

                                            avctx->extradata_size, &header_size,

                                            c->coeff)) < 0) {

            av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");

            return AVERROR_INVALIDDATA;

        }

        c->channels      = avctx->channels;

        c->header_parsed = 1;

    }

    avctx->sample_fmt = AV_SAMPLE_FMT_S16P;

    return 0;

}

/**

 * Decode 32 samples from 18 bytes.

 *

 * A 16-bit scalar value is applied to 32 residuals, which then have a

 * 2nd-order LPC filter applied to it to form the output signal for a single

 * channel.

 */

static int adx_decode(ADXContext *c, int16_t *out, int offset,

                      const uint8_t *in, int ch)

{

    ADXChannelState *prev = &c->prev[ch];

    GetBitContext gb;

    int scale = AV_RB16(in);

    int i;

    int s0, s1, s2, d;

    /* check if this is an EOF packet */

    if (scale & 0x8000)

        return -1;

    init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);

    out += offset;

    s1 = prev->s1;

    s2 = prev->s2;

    for (i = 0; i < BLOCK_SAMPLES; i++) {

        d  = get_sbits(&gb, 4);

        s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;

        s2 = s1;

        s1 = av_clip_int16(s0);

        *out++ = s1;

    }

    prev->s1 = s1;

    prev->s2 = s2;

    return 0;

}

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

                            int *got_frame_ptr, AVPacket *avpkt)

{

    AVFrame *frame      = data;

    int buf_size        = avpkt->size;

    ADXContext *c       = avctx->priv_data;

    int16_t **samples;

    int samples_offset;

    const uint8_t *buf  = avpkt->data;

    const uint8_t *buf_end = buf + avpkt->size;

    int num_blocks, ch, ret;

    if (c->eof) {

        *got_frame_ptr = 0;

        return buf_size;

    }

    if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {

        int header_size;

        if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,

                                            c->coeff)) < 0) {

            av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");

            return AVERROR_INVALIDDATA;

        }

        c->channels      = avctx->channels;

        c->header_parsed = 1;

        if (buf_size < header_size)

            return AVERROR_INVALIDDATA;

        buf      += header_size;

        buf_size -= header_size;

    }

    if (!c->header_parsed)

        return AVERROR_INVALIDDATA;

    /* calculate number of blocks in the packet */

    num_blocks = buf_size / (BLOCK_SIZE * c->channels);

    /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF

       packet */

    if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {

        if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {

            c->eof = 1;

            *got_frame_ptr = 0;

            return avpkt->size;

        }

        return AVERROR_INVALIDDATA;

    }

    /* get output buffer */

    frame->nb_samples = num_blocks * BLOCK_SAMPLES;

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

        return ret;

    samples = (int16_t **)frame->extended_data;

    samples_offset = 0;

    while (num_blocks--) {

        for (ch = 0; ch < c->channels; ch++) {

            if (buf_end - buf < BLOCK_SIZE || adx_decode(c, samples[ch], samples_offset, buf, ch)) {

                c->eof = 1;

                buf = avpkt->data + avpkt->size;

                break;

            }

            buf_size -= BLOCK_SIZE;

            buf      += BLOCK_SIZE;

        }

        samples_offset += BLOCK_SAMPLES;

    }

    *got_frame_ptr = 1;

    return buf - avpkt->data;

}

static void adx_decode_flush(AVCodecContext *avctx)

{

    ADXContext *c = avctx->priv_data;

    memset(c->prev, 0, sizeof(c->prev));

    c->eof = 0;

}

AVCodec ff_adpcm_adx_decoder = {

    .name           = "adpcm_adx",

    .long_name      = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),

    .type           = AVMEDIA_TYPE_AUDIO,

    .id             = AV_CODEC_ID_ADPCM_ADX,

    .priv_data_size = sizeof(ADXContext),

    .init           = adx_decode_init,

    .decode         = adx_decode_frame,

    .flush          = adx_decode_flush,

    .capabilities   = CODEC_CAP_DR1,

    .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,

                                                      AV_SAMPLE_FMT_NONE },

};