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/*

 * TTA (The Lossless True Audio) encoder

 *

 * 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

 */

#define BITSTREAM_WRITER_LE

#include "ttadata.h"

#include "avcodec.h"

#include "put_bits.h"

#include "internal.h"

#include "libavutil/crc.h"

typedef struct TTAEncContext {

    const AVCRC *crc_table;

    int bps;

    TTAChannel *ch_ctx;

} TTAEncContext;

static av_cold int tta_encode_init(AVCodecContext *avctx)

{

    TTAEncContext *s = avctx->priv_data;

    s->crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);

    switch (avctx->sample_fmt) {

    case AV_SAMPLE_FMT_U8:

        avctx->bits_per_raw_sample = 8;

        break;

    case AV_SAMPLE_FMT_S16:

        avctx->bits_per_raw_sample = 16;

        break;

    case AV_SAMPLE_FMT_S32:

        if (avctx->bits_per_raw_sample > 24)

            av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");

        avctx->bits_per_raw_sample = 24;

    }

    s->bps = avctx->bits_per_raw_sample >> 3;

    avctx->frame_size = 256 * avctx->sample_rate / 245;

    s->ch_ctx = av_malloc(avctx->channels * sizeof(*s->ch_ctx));

    if (!s->ch_ctx)

        return AVERROR(ENOMEM);

    return 0;

}

static inline void ttafilter_process(TTAFilter *c, int32_t *in)

{

    register int32_t *dl = c->dl, *qm = c->qm, *dx = c->dx, sum = c->round;

    if (c->error < 0) {

        qm[0] -= dx[0]; qm[1] -= dx[1]; qm[2] -= dx[2]; qm[3] -= dx[3];

        qm[4] -= dx[4]; qm[5] -= dx[5]; qm[6] -= dx[6]; qm[7] -= dx[7];

    } else if (c->error > 0) {

        qm[0] += dx[0]; qm[1] += dx[1]; qm[2] += dx[2]; qm[3] += dx[3];

        qm[4] += dx[4]; qm[5] += dx[5]; qm[6] += dx[6]; qm[7] += dx[7];

    }

    sum += dl[0] * qm[0] + dl[1] * qm[1] + dl[2] * qm[2] + dl[3] * qm[3] +

           dl[4] * qm[4] + dl[5] * qm[5] + dl[6] * qm[6] + dl[7] * qm[7];

    dx[0] = dx[1]; dx[1] = dx[2]; dx[2] = dx[3]; dx[3] = dx[4];

    dl[0] = dl[1]; dl[1] = dl[2]; dl[2] = dl[3]; dl[3] = dl[4];

    dx[4] = ((dl[4] >> 30) | 1);

    dx[5] = ((dl[5] >> 30) | 2) & ~1;

    dx[6] = ((dl[6] >> 30) | 2) & ~1;

    dx[7] = ((dl[7] >> 30) | 4) & ~3;

    dl[4] = -dl[5]; dl[5] = -dl[6];

    dl[6] = *in - dl[7]; dl[7] = *in;

    dl[5] += dl[6]; dl[4] += dl[5];

    *in -= (sum >> c->shift);

    c->error = *in;

}

static int32_t get_sample(const AVFrame *frame, int sample,

                          enum AVSampleFormat format)

{

    int32_t ret;

    if (format == AV_SAMPLE_FMT_U8) {

        ret = frame->data[0][sample] - 0x80;

    } else if (format == AV_SAMPLE_FMT_S16) {

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

        ret = ptr[sample];

    } else {

        const int32_t *ptr = (const int32_t *)frame->data[0];

        ret = ptr[sample] >> 8;

    }

    return ret;

}

static int tta_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,

                            const AVFrame *frame, int *got_packet_ptr)

{

    TTAEncContext *s = avctx->priv_data;

    PutBitContext pb;

    int ret, i, out_bytes, cur_chan = 0, res = 0, samples = 0;

    if ((ret = ff_alloc_packet2(avctx, avpkt, frame->nb_samples * 2 * avctx->channels * s->bps)) < 0)

        return ret;

    init_put_bits(&pb, avpkt->data, avpkt->size);

    // init per channel states

    for (i = 0; i < avctx->channels; i++) {

        s->ch_ctx[i].predictor = 0;

        ff_tta_filter_init(&s->ch_ctx[i].filter, ff_tta_filter_configs[s->bps - 1]);

        ff_tta_rice_init(&s->ch_ctx[i].rice, 10, 10);

    }

    for (i = 0; i < frame->nb_samples * avctx->channels; i++) {

        TTAChannel *c = &s->ch_ctx[cur_chan];

        TTAFilter *filter = &c->filter;

        TTARice *rice = &c->rice;

        uint32_t k, unary, outval;

        int32_t value, temp;

        value = get_sample(frame, samples++, avctx->sample_fmt);

        if (avctx->channels > 1) {

            if (cur_chan < avctx->channels - 1)

                value  = res = get_sample(frame, samples, avctx->sample_fmt) - value;

            else

                value -= res / 2;

        }

        temp = value;

#define PRED(x, k) (int32_t)((((uint64_t)x << k) - x) >> k)

        switch (s->bps) {

        case 1: value -= PRED(c->predictor, 4); break;

        case 2:

        case 3: value -= PRED(c->predictor, 5); break;

        }

        c->predictor = temp;

        ttafilter_process(filter, &value);

        outval = (value > 0) ? (value << 1) - 1: -value << 1;

        k = rice->k0;

        rice->sum0 += outval - (rice->sum0 >> 4);

        if (rice->k0 > 0 && rice->sum0 < ff_tta_shift_16[rice->k0])

            rice->k0--;

        else if (rice->sum0 > ff_tta_shift_16[rice->k0 + 1])

            rice->k0++;

        if (outval >= ff_tta_shift_1[k]) {

            outval -= ff_tta_shift_1[k];

            k = rice->k1;

            rice->sum1 += outval - (rice->sum1 >> 4);

            if (rice->k1 > 0 && rice->sum1 < ff_tta_shift_16[rice->k1])

                rice->k1--;

            else if (rice->sum1 > ff_tta_shift_16[rice->k1 + 1])

                rice->k1++;

            unary = 1 + (outval >> k);

            do {

                if (unary > 31) {

                    put_bits(&pb, 31, 0x7FFFFFFF);

                    unary -= 31;

                } else {

                    put_bits(&pb, unary, (1 << unary) - 1);

                    unary = 0;

                }

            } while (unary);

        }

        put_bits(&pb, 1, 0);

        if (k)

            put_bits(&pb, k, outval & (ff_tta_shift_1[k] - 1));

        if (cur_chan < avctx->channels - 1)

            cur_chan++;

        else

            cur_chan = 0;

    }

    flush_put_bits(&pb);

    out_bytes = put_bits_count(&pb) >> 3;

    put_bits32(&pb, av_crc(s->crc_table, UINT32_MAX, avpkt->data, out_bytes) ^ UINT32_MAX);

    flush_put_bits(&pb);

    avpkt->pts      = frame->pts;

    avpkt->size     = out_bytes + 4;

    avpkt->duration = ff_samples_to_time_base(avctx, frame->nb_samples);

    *got_packet_ptr = 1;

    return 0;

}

static av_cold int tta_encode_close(AVCodecContext *avctx)

{

    TTAEncContext *s = avctx->priv_data;

    av_freep(&s->ch_ctx);

    return 0;

}

AVCodec ff_tta_encoder = {

    .name           = "tta",

    .long_name      = NULL_IF_CONFIG_SMALL("TTA (True Audio)"),

    .type           = AVMEDIA_TYPE_AUDIO,

    .id             = AV_CODEC_ID_TTA,

    .priv_data_size = sizeof(TTAEncContext),

    .init           = tta_encode_init,

    .close          = tta_encode_close,

    .encode2        = tta_encode_frame,

    .capabilities   = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_LOSSLESS,

    .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_U8,

                                                     AV_SAMPLE_FMT_S16,

                                                     AV_SAMPLE_FMT_S32,

                                                     AV_SAMPLE_FMT_NONE },

};