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ffmpeg / libavcodec / dvbsub_parser.c @ 2912e87a

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/*
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 * DVB subtitle parser for Libav
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 * Copyright (c) 2005 Ian Caulfield
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "avcodec.h"
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#include "dsputil.h"
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#include "get_bits.h"
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//#define DEBUG
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//#define DEBUG_PACKET_CONTENTS
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/* Parser (mostly) copied from dvdsub.c */
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#define PARSE_BUF_SIZE  (65536)
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/* parser definition */
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typedef struct DVBSubParseContext {
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    uint8_t *packet_buf;
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    int packet_start;
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    int packet_index;
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    int in_packet;
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} DVBSubParseContext;
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static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
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{
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    DVBSubParseContext *pc = s->priv_data;
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    pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
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    return 0;
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}
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static int dvbsub_parse(AVCodecParserContext *s,
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                        AVCodecContext *avctx,
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                        const uint8_t **poutbuf, int *poutbuf_size,
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                        const uint8_t *buf, int buf_size)
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{
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    DVBSubParseContext *pc = s->priv_data;
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    uint8_t *p, *p_end;
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    int len, buf_pos = 0;
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    av_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
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            s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
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#ifdef DEBUG_PACKET_CONTENTS
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    int i;
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    for (i=0; i < buf_size; i++)
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    {
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        av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
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        if (i % 16 == 15)
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            av_log(avctx, AV_LOG_INFO, "\n");
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    }
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    if (i % 16 != 0)
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        av_log(avctx, AV_LOG_INFO, "\n");
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#endif
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    *poutbuf = NULL;
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    *poutbuf_size = 0;
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    s->fetch_timestamp = 1;
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    if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
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    {
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        if (pc->packet_index != pc->packet_start)
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        {
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            av_dlog(avctx, "Discarding %d bytes\n",
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                    pc->packet_index - pc->packet_start);
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        }
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        pc->packet_start = 0;
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        pc->packet_index = 0;
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        if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
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            av_dlog(avctx, "Bad packet header\n");
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            return -1;
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        }
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        buf_pos = 2;
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        pc->in_packet = 1;
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    } else {
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        if (pc->packet_start != 0)
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        {
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            if (pc->packet_index != pc->packet_start)
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            {
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                memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
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                            pc->packet_index - pc->packet_start);
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                pc->packet_index -= pc->packet_start;
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                pc->packet_start = 0;
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            } else {
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                pc->packet_start = 0;
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                pc->packet_index = 0;
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            }
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        }
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    }
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    if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
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        return -1;
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/* if not currently in a packet, discard data */
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    if (pc->in_packet == 0)
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        return buf_size;
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    memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
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    pc->packet_index += buf_size - buf_pos;
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    p = pc->packet_buf;
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    p_end = pc->packet_buf + pc->packet_index;
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    while (p < p_end)
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    {
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        if (*p == 0x0f)
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        {
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            if (p + 6 <= p_end)
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            {
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                len = AV_RB16(p + 4);
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                if (p + len + 6 <= p_end)
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                {
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                    *poutbuf_size += len + 6;
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                    p += len + 6;
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                } else
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                    break;
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            } else
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                break;
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        } else if (*p == 0xff) {
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            if (p + 1 < p_end)
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            {
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                av_dlog(avctx, "Junk at end of packet\n");
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            }
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            pc->packet_index = p - pc->packet_buf;
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            pc->in_packet = 0;
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            break;
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        } else {
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            av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
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            pc->packet_index = p - pc->packet_buf;
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            pc->in_packet = 0;
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            break;
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        }
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    }
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    if (*poutbuf_size > 0)
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    {
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        *poutbuf = pc->packet_buf;
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        pc->packet_start = *poutbuf_size;
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    }
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    if (s->pts == AV_NOPTS_VALUE)
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        s->pts = s->last_pts;
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    return buf_size;
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}
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static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
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{
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    DVBSubParseContext *pc = s->priv_data;
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    av_freep(&pc->packet_buf);
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}
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AVCodecParser ff_dvbsub_parser = {
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    { CODEC_ID_DVB_SUBTITLE },
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    sizeof(DVBSubParseContext),
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    dvbsub_parse_init,
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    dvbsub_parse,
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    dvbsub_parse_close,
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};