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
27#include "avcodec.h"
28
29/* Parser (mostly) copied from dvdsub.c */
30
31#define PARSE_BUF_SIZE  (65536)
32
33
34/* parser definition */
35typedef struct DVBSubParseContext {
36    int packet_start;
37    int packet_index;
38    int in_packet;
39    uint8_t packet_buf[PARSE_BUF_SIZE];
40} DVBSubParseContext;
41
42static int dvbsub_parse(AVCodecParserContext *s,
43                        AVCodecContext *avctx,
44                        const uint8_t **poutbuf, int *poutbuf_size,
45                        const uint8_t *buf, int buf_size)
46{
47    DVBSubParseContext *pc = s->priv_data;
48    uint8_t *p, *p_end;
49    int i, len, buf_pos = 0;
50    int out_size = 0;
51
52    ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
53            s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
54
55    for (i=0; i < buf_size; i++)
56    {
57        ff_dlog(avctx, "%02x ", buf[i]);
58        if (i % 16 == 15)
59            ff_dlog(avctx, "\n");
60    }
61
62    if (i % 16 != 0)
63        ff_dlog(avctx, "\n");
64
65    *poutbuf      = buf;
66    *poutbuf_size = buf_size;
67
68    s->fetch_timestamp = 1;
69
70    if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
71    {
72        if (pc->packet_index != pc->packet_start)
73        {
74            ff_dlog(avctx, "Discarding %d bytes\n",
75                    pc->packet_index - pc->packet_start);
76        }
77
78        pc->packet_start = 0;
79        pc->packet_index = 0;
80
81        if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
82            ff_dlog(avctx, "Bad packet header\n");
83            return buf_size;
84        }
85
86        buf_pos = 2;
87
88        pc->in_packet = 1;
89    } else {
90        if (pc->packet_start != 0)
91        {
92            if (pc->packet_index != pc->packet_start)
93            {
94                memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
95                            pc->packet_index - pc->packet_start);
96
97                pc->packet_index -= pc->packet_start;
98                pc->packet_start = 0;
99            } else {
100                pc->packet_start = 0;
101                pc->packet_index = 0;
102            }
103        }
104    }
105
106    if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
107        return buf_size;
108
109/* if not currently in a packet, pass data */
110    if (pc->in_packet == 0)
111        return buf_size;
112
113    memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
114    pc->packet_index += buf_size - buf_pos;
115
116    p = pc->packet_buf;
117    p_end = pc->packet_buf + pc->packet_index;
118
119    while (p < p_end)
120    {
121        if (*p == 0x0f)
122        {
123            if (6 <= p_end - p)
124            {
125                len = AV_RB16(p + 4);
126
127                if (len + 6 <= p_end - p)
128                {
129                    out_size += len + 6;
130
131                    p += len + 6;
132                } else
133                    break;
134            } else
135                break;
136        } else if (*p == 0xff) {
137            if (1 < p_end - p)
138            {
139                ff_dlog(avctx, "Junk at end of packet\n");
140            }
141            pc->packet_index = p - pc->packet_buf;
142            pc->in_packet = 0;
143            break;
144        } else {
145            av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
146
147            pc->packet_index = p - pc->packet_buf;
148            pc->in_packet = 0;
149            break;
150        }
151    }
152
153    if (out_size > 0)
154    {
155        *poutbuf = pc->packet_buf;
156        *poutbuf_size = out_size;
157        pc->packet_start = *poutbuf_size;
158    }
159
160    if (s->pts == AV_NOPTS_VALUE)
161        s->pts = s->last_pts;
162
163    return buf_size;
164}
165
166const AVCodecParser ff_dvbsub_parser = {
167    .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
168    .priv_data_size = sizeof(DVBSubParseContext),
169    .parser_parse   = dvbsub_parse,
170};
171