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/*

 * Copyright (c) 2012 Clément Bœsch

 *

 * 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

 * Raw subtitles decoder

 */

#include "avcodec.h"

#include "ass.h"

#include "libavutil/bprint.h"

#include "libavutil/opt.h"

typedef struct {

    AVClass *class;

    const char *linebreaks;

    int keep_ass_markup;

} TextContext;

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

#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {

    { "keep_ass_markup", "Set if ASS tags must be escaped", OFFSET(keep_ass_markup), AV_OPT_TYPE_INT,    {.i64=0}, 0, 1, .flags=SD },

    { NULL }

};

static int text_event_to_ass(const AVCodecContext *avctx, AVBPrint *buf,

                             const char *p, const char *p_end)

{

    const TextContext *text = avctx->priv_data;

    for (; p < p_end && *p; p++) {

        /* forced custom line breaks, not accounted as "normal" EOL */

        if (text->linebreaks && strchr(text->linebreaks, *p)) {

            av_bprintf(buf, "\\N");

        /* standard ASS escaping so random characters don't get mis-interpreted

         * as ASS */

        } else if (!text->keep_ass_markup && strchr("{}\\", *p)) {

            av_bprintf(buf, "\\%c", *p);

        /* some packets might end abruptly (no \0 at the end, like for example

         * in some cases of demuxing from a classic video container), some

         * might be terminated with \n or \r\n which we have to remove (for

         * consistency with those who haven't), and we also have to deal with

         * evil cases such as \r at the end of the buffer (and no \0 terminated

         * character) */

        } else if (p[0] == '\n') {

            /* some stuff left so we can insert a line break */

            if (p < p_end - 1)

                av_bprintf(buf, "\\N");

        } else if (p[0] == '\r' && p < p_end - 1 && p[1] == '\n') {

            /* \r followed by a \n, we can skip it. We don't insert the \N yet

             * because we don't know if it is followed by more text */

            continue;

        /* finally, a sane character */

        } else {

            av_bprint_chars(buf, *p, 1);

        }

    }

    av_bprintf(buf, "\r\n");

    return 0;

}

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

                             int *got_sub_ptr, AVPacket *avpkt)

{

    AVBPrint buf;

    AVSubtitle *sub = data;

    const char *ptr = avpkt->data;

    const int ts_start     = av_rescale_q(avpkt->pts,      avctx->time_base, (AVRational){1,100});

    const int ts_duration  = avpkt->duration != -1 ?

                             av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;

    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

    if (ptr && avpkt->size > 0 && *ptr &&

        !text_event_to_ass(avctx, &buf, ptr, ptr + avpkt->size)) {

        if (!av_bprint_is_complete(&buf)) {

            av_bprint_finalize(&buf, NULL);

            return AVERROR(ENOMEM);

        }

        ff_ass_add_rect(sub, buf.str, ts_start, ts_duration, 0);

    }

    *got_sub_ptr = sub->num_rects > 0;

    av_bprint_finalize(&buf, NULL);

    return avpkt->size;

}

#define DECLARE_CLASS(decname) static const AVClass decname ## _decoder_class = {   \

    .class_name = #decname " decoder",      \

    .item_name  = av_default_item_name,     \

    .option     = decname ## _options,      \

    .version    = LIBAVUTIL_VERSION_INT,    \

}

#if CONFIG_TEXT_DECODER

#define text_options options

DECLARE_CLASS(text);

AVCodec ff_text_decoder = {

    .name           = "text",

    .long_name      = NULL_IF_CONFIG_SMALL("Raw text subtitle"),

    .priv_data_size = sizeof(TextContext),

    .type           = AVMEDIA_TYPE_SUBTITLE,

    .id             = AV_CODEC_ID_TEXT,

    .decode         = text_decode_frame,

    .init           = ff_ass_subtitle_header_default,

    .priv_class     = &text_decoder_class,

};

#endif

#if CONFIG_VPLAYER_DECODER || CONFIG_PJS_DECODER || CONFIG_SUBVIEWER1_DECODER

static int linebreak_init(AVCodecContext *avctx)

{

    TextContext *text = avctx->priv_data;

    text->linebreaks = "|";

    return ff_ass_subtitle_header_default(avctx);

}

#if CONFIG_VPLAYER_DECODER

#define vplayer_options options

DECLARE_CLASS(vplayer);

AVCodec ff_vplayer_decoder = {

    .name           = "vplayer",

    .long_name      = NULL_IF_CONFIG_SMALL("VPlayer subtitle"),

    .priv_data_size = sizeof(TextContext),

    .type           = AVMEDIA_TYPE_SUBTITLE,

    .id             = AV_CODEC_ID_VPLAYER,

    .decode         = text_decode_frame,

    .init           = linebreak_init,

    .priv_class     = &vplayer_decoder_class,

};

#endif

#if CONFIG_PJS_DECODER

#define pjs_options options

DECLARE_CLASS(pjs);

AVCodec ff_pjs_decoder = {

    .name           = "pjs",

    .long_name      = NULL_IF_CONFIG_SMALL("PJS subtitle"),

    .priv_data_size = sizeof(TextContext),

    .type           = AVMEDIA_TYPE_SUBTITLE,

    .id             = AV_CODEC_ID_PJS,

    .decode         = text_decode_frame,

    .init           = linebreak_init,

    .priv_class     = &pjs_decoder_class,

};

#endif

#if CONFIG_SUBVIEWER1_DECODER

#define subviewer1_options options

DECLARE_CLASS(subviewer1);

AVCodec ff_subviewer1_decoder = {

    .name           = "subviewer1",

    .long_name      = NULL_IF_CONFIG_SMALL("SubViewer1 subtitle"),

    .priv_data_size = sizeof(TextContext),

    .type           = AVMEDIA_TYPE_SUBTITLE,

    .id             = AV_CODEC_ID_SUBVIEWER1,

    .decode         = text_decode_frame,

    .init           = linebreak_init,

    .priv_class     = &subviewer1_decoder_class,

};

#endif

#endif /* text subtitles with '|' line break */