/libavcodec/dvbsub_parser.c

  1/*
  2 * DVB subtitle parser for FFmpeg
  3 * Copyright (c) 2005 Ian Caulfield
  4 *
  5 * This file is part of FFmpeg.
  6 *
  7 * FFmpeg is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU Lesser General Public
  9 * License as published by the Free Software Foundation; either
 10 * version 2.1 of the License, or (at your option) any later version.
 11 *
 12 * FFmpeg is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 15 * Lesser General Public License for more details.
 16 *
 17 * You should have received a copy of the GNU Lesser General Public
 18 * License along with FFmpeg; if not, write to the Free Software
 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 20 */
 21
 22#include <inttypes.h>
 23#include <string.h>
 24
 25#include "libavutil/intreadwrite.h"
 26#include "libavutil/mem.h"
 27
 28#include "avcodec.h"
 29#include "internal.h"
 30
 31/* Parser (mostly) copied from dvdsub.c */
 32
 33#define PARSE_BUF_SIZE  (65536)
 34
 35
 36/* parser definition */
 37typedef struct DVBSubParseContext {
 38    uint8_t *packet_buf;
 39    int packet_start;
 40    int packet_index;
 41    int in_packet;
 42} DVBSubParseContext;
 43
 44static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
 45{
 46    DVBSubParseContext *pc = s->priv_data;
 47    pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
 48
 49    return 0;
 50}
 51
 52static int dvbsub_parse(AVCodecParserContext *s,
 53                        AVCodecContext *avctx,
 54                        const uint8_t **poutbuf, int *poutbuf_size,
 55                        const uint8_t *buf, int buf_size)
 56{
 57    DVBSubParseContext *pc = s->priv_data;
 58    uint8_t *p, *p_end;
 59    int i, len, buf_pos = 0;
 60    int out_size = 0;
 61
 62    ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
 63            s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
 64
 65    for (i=0; i < buf_size; i++)
 66    {
 67        ff_dlog(avctx, "%02x ", buf[i]);
 68        if (i % 16 == 15)
 69            ff_dlog(avctx, "\n");
 70    }
 71
 72    if (i % 16 != 0)
 73        ff_dlog(avctx, "\n");
 74
 75    *poutbuf      = buf;
 76    *poutbuf_size = buf_size;
 77
 78    s->fetch_timestamp = 1;
 79
 80    if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
 81    {
 82        if (pc->packet_index != pc->packet_start)
 83        {
 84            ff_dlog(avctx, "Discarding %d bytes\n",
 85                    pc->packet_index - pc->packet_start);
 86        }
 87
 88        pc->packet_start = 0;
 89        pc->packet_index = 0;
 90
 91        if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
 92            ff_dlog(avctx, "Bad packet header\n");
 93            return buf_size;
 94        }
 95
 96        buf_pos = 2;
 97
 98        pc->in_packet = 1;
 99    } else {
100        if (pc->packet_start != 0)
101        {
102            if (pc->packet_index != pc->packet_start)
103            {
104                memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
105                            pc->packet_index - pc->packet_start);
106
107                pc->packet_index -= pc->packet_start;
108                pc->packet_start = 0;
109            } else {
110                pc->packet_start = 0;
111                pc->packet_index = 0;
112            }
113        }
114    }
115
116    if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
117        return buf_size;
118
119/* if not currently in a packet, pass data */
120    if (pc->in_packet == 0)
121        return buf_size;
122
123    memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
124    pc->packet_index += buf_size - buf_pos;
125
126    p = pc->packet_buf;
127    p_end = pc->packet_buf + pc->packet_index;
128
129    while (p < p_end)
130    {
131        if (*p == 0x0f)
132        {
133            if (6 <= p_end - p)
134            {
135                len = AV_RB16(p + 4);
136
137                if (len + 6 <= p_end - p)
138                {
139                    out_size += len + 6;
140
141                    p += len + 6;
142                } else
143                    break;
144            } else
145                break;
146        } else if (*p == 0xff) {
147            if (1 < p_end - p)
148            {
149                ff_dlog(avctx, "Junk at end of packet\n");
150            }
151            pc->packet_index = p - pc->packet_buf;
152            pc->in_packet = 0;
153            break;
154        } else {
155            av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
156
157            pc->packet_index = p - pc->packet_buf;
158            pc->in_packet = 0;
159            break;
160        }
161    }
162
163    if (out_size > 0)
164    {
165        *poutbuf = pc->packet_buf;
166        *poutbuf_size = out_size;
167        pc->packet_start = *poutbuf_size;
168    }
169
170    if (s->pts == AV_NOPTS_VALUE)
171        s->pts = s->last_pts;
172
173    return buf_size;
174}
175
176static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
177{
178    DVBSubParseContext *pc = s->priv_data;
179    av_freep(&pc->packet_buf);
180}
181
182AVCodecParser ff_dvbsub_parser = {
183    .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
184    .priv_data_size = sizeof(DVBSubParseContext),
185    .parser_init    = dvbsub_parse_init,
186    .parser_parse   = dvbsub_parse,
187    .parser_close   = dvbsub_parse_close,
188};