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/*

 * DVB subtitle parser for FFmpeg

 * Copyright (c) 2005 Ian Caulfield

 *

 * 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 "avcodec.h"

#include "get_bits.h"

/* Parser (mostly) copied from dvdsub.c */

#define PARSE_BUF_SIZE  (65536)

/* parser definition */

typedef struct DVBSubParseContext {

    uint8_t *packet_buf;

    int packet_start;

    int packet_index;

    int in_packet;

} DVBSubParseContext;

static av_cold int dvbsub_parse_init(AVCodecParserContext *s)

{

    DVBSubParseContext *pc = s->priv_data;

    pc->packet_buf = av_malloc(PARSE_BUF_SIZE);

    return 0;

}

static int dvbsub_parse(AVCodecParserContext *s,

                        AVCodecContext *avctx,

                        const uint8_t **poutbuf, int *poutbuf_size,

                        const uint8_t *buf, int buf_size)

{

    DVBSubParseContext *pc = s->priv_data;

    uint8_t *p, *p_end;

    int i, len, buf_pos = 0;

    av_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",

            s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);

    for (i=0; i < buf_size; i++)

    {

        av_dlog(avctx, "%02x ", buf[i]);

        if (i % 16 == 15)

            av_dlog(avctx, "\n");

    }

    if (i % 16 != 0)

        av_dlog(avctx, "\n");

    *poutbuf = NULL;

    *poutbuf_size = 0;

    s->fetch_timestamp = 1;

    if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */

    {

        if (pc->packet_index != pc->packet_start)

        {

            av_dlog(avctx, "Discarding %d bytes\n",

                    pc->packet_index - pc->packet_start);

        }

        pc->packet_start = 0;

        pc->packet_index = 0;

        if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {

            av_dlog(avctx, "Bad packet header\n");

            return -1;

        }

        buf_pos = 2;

        pc->in_packet = 1;

    } else {

        if (pc->packet_start != 0)

        {

            if (pc->packet_index != pc->packet_start)

            {

                memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,

                            pc->packet_index - pc->packet_start);

                pc->packet_index -= pc->packet_start;

                pc->packet_start = 0;

            } else {

                pc->packet_start = 0;

                pc->packet_index = 0;

            }

        }

    }

    if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)

        return -1;

/* if not currently in a packet, discard data */

    if (pc->in_packet == 0)

        return buf_size;

    memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);

    pc->packet_index += buf_size - buf_pos;

    p = pc->packet_buf;

    p_end = pc->packet_buf + pc->packet_index;

    while (p < p_end)

    {

        if (*p == 0x0f)

        {

            if (p + 6 <= p_end)

            {

                len = AV_RB16(p + 4);

                if (p + len + 6 <= p_end)

                {

                    *poutbuf_size += len + 6;

                    p += len + 6;

                } else

                    break;

            } else

                break;

        } else if (*p == 0xff) {

            if (p + 1 < p_end)

            {

                av_dlog(avctx, "Junk at end of packet\n");

            }

            pc->packet_index = p - pc->packet_buf;

            pc->in_packet = 0;

            break;

        } else {

            av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");

            pc->packet_index = p - pc->packet_buf;

            pc->in_packet = 0;

            break;

        }

    }

    if (*poutbuf_size > 0)

    {

        *poutbuf = pc->packet_buf;

        pc->packet_start = *poutbuf_size;

    }

    if (s->pts == AV_NOPTS_VALUE)

        s->pts = s->last_pts;

    return buf_size;

}

static av_cold void dvbsub_parse_close(AVCodecParserContext *s)

{

    DVBSubParseContext *pc = s->priv_data;

    av_freep(&pc->packet_buf);

}

AVCodecParser ff_dvbsub_parser = {

    .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },

    .priv_data_size = sizeof(DVBSubParseContext),

    .parser_init    = dvbsub_parse_init,

    .parser_parse   = dvbsub_parse,

    .parser_close   = dvbsub_parse_close,

};