/*

 * Copyright (c) 2021 Paul B Mahol

 *

 * 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

 * AMR audio parser

 *

 * Splits packets into individual blocks.

 */

#include "libavutil/channel_layout.h"

#include "libavutil/intreadwrite.h"

#include "parser.h"

#include "parser_internal.h"

static const uint8_t amrnb_packed_size[16] = {

    13, 14, 16, 18, 20, 21, 27, 32, 6, 1, 1, 1, 1, 1, 1, 1

};

static const uint8_t amrwb_packed_size[16] = {

    18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 1, 1, 1, 1, 1, 1

};

typedef struct AMRParseContext {

    ParseContext pc;

    uint64_t cumulated_size;

    uint64_t block_count;

    int current_channel;

    int remaining;

} AMRParseContext;

static av_cold int amr_parse_init(AVCodecParserContext *s1)

{

    AMRParseContext *s = s1->priv_data;

    s->remaining = -1;

    return 0;

}

static int amr_parse(AVCodecParserContext *s1,

                     AVCodecContext *avctx,

                     const uint8_t **poutbuf, int *poutbuf_size,

                     const uint8_t *buf, int buf_size)

{

    AMRParseContext *s = s1->priv_data;

    ParseContext *pc = &s->pc;

    int next = END_NOT_FOUND;

    *poutbuf_size = 0;

    *poutbuf = NULL;

    if (!avctx->ch_layout.nb_channels) {

        av_channel_layout_uninit(&avctx->ch_layout);

        avctx->ch_layout      = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;

    }

    if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {

        next = buf_size;

    } else {

        int ch, offset = 0;

        for (ch = s->current_channel; ch < avctx->ch_layout.nb_channels; ch++) {

            if (s->remaining >= 0) {

                next = s->remaining;

            } else {

                int mode = (buf[offset] >> 3) & 0x0F;

                if (avctx->codec_id == AV_CODEC_ID_AMR_NB) {

                    next = amrnb_packed_size[mode];

                } else if (avctx->codec_id == AV_CODEC_ID_AMR_WB) {

                    next = amrwb_packed_size[mode];

                }

            }

            offset += next;

            if (offset >= buf_size) {

                s->remaining = offset - buf_size;

                next = END_NOT_FOUND;

                break;

            } else {

                s->remaining = -1;

            }

        }

        s->current_channel = ch % avctx->ch_layout.nb_channels;

        if (s->remaining < 0)

            next = offset;

        if (next != END_NOT_FOUND) {

            if (s->cumulated_size < UINT64_MAX - next) {

                s->cumulated_size += next;

                /* Both AMR formats have 50 frames per second */

                avctx->bit_rate = s->cumulated_size / ++s->block_count * 8 * 50;

            }

        }

        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

            *poutbuf      = NULL;

            *poutbuf_size = 0;

            return buf_size;

        }

    }

    s1->duration = avctx->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;

    *poutbuf = buf;

    *poutbuf_size = buf_size;

    return next;

}

const FFCodecParser ff_amr_parser = {

    PARSER_CODEC_LIST(AV_CODEC_ID_AMR_NB, AV_CODEC_ID_AMR_WB),

    .priv_data_size = sizeof(AMRParseContext),

    .init           = amr_parse_init,

    .parse          = amr_parse,

    .close          = ff_parse_close,

};