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#include "avcodec.h"
22#include "dsputil.h"
23#include "get_bits.h"
24
25//#define DEBUG
26//#define DEBUG_PACKET_CONTENTS
27
28/* Parser (mostly) copied from dvdsub.c */
29
30#define PARSE_BUF_SIZE  (65536)
31
32
33/* parser definition */
34typedef struct DVBSubParseContext {
35    uint8_t *packet_buf;
36    int packet_start;
37    int packet_index;
38    int in_packet;
39} DVBSubParseContext;
40
41static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
42{
43    DVBSubParseContext *pc = s->priv_data;
44    pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
45
46    return 0;
47}
48
49static int dvbsub_parse(AVCodecParserContext *s,
50                        AVCodecContext *avctx,
51                        const uint8_t **poutbuf, int *poutbuf_size,
52                        const uint8_t *buf, int buf_size)
53{
54    DVBSubParseContext *pc = s->priv_data;
55    uint8_t *p, *p_end;
56    int len, buf_pos = 0;
57
58    dprintf(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
59            s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
60
61#ifdef DEBUG_PACKET_CONTENTS
62    int i;
63
64    for (i=0; i < buf_size; i++)
65    {
66        av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
67        if (i % 16 == 15)
68            av_log(avctx, AV_LOG_INFO, "\n");
69    }
70
71    if (i % 16 != 0)
72        av_log(avctx, AV_LOG_INFO, "\n");
73
74#endif
75
76    *poutbuf = NULL;
77    *poutbuf_size = 0;
78
79    s->fetch_timestamp = 1;
80
81    if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
82    {
83        if (pc->packet_index != pc->packet_start)
84        {
85            dprintf(avctx, "Discarding %d bytes\n",
86                    pc->packet_index - pc->packet_start);
87        }
88
89        pc->packet_start = 0;
90        pc->packet_index = 0;
91
92        if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
93            dprintf(avctx, "Bad packet header\n");
94            return -1;
95        }
96
97        buf_pos = 2;
98
99        pc->in_packet = 1;
100    } else {
101        if (pc->packet_start != 0)
102        {
103            if (pc->packet_index != pc->packet_start)
104            {
105                memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
106                            pc->packet_index - pc->packet_start);
107
108                pc->packet_index -= pc->packet_start;
109                pc->packet_start = 0;
110            } else {
111                pc->packet_start = 0;
112                pc->packet_index = 0;
113            }
114        }
115    }
116
117    if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
118        return -1;
119
120/* if not currently in a packet, discard data */
121    if (pc->in_packet == 0)
122        return buf_size;
123
124    memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
125    pc->packet_index += buf_size - buf_pos;
126
127    p = pc->packet_buf;
128    p_end = pc->packet_buf + pc->packet_index;
129
130    while (p < p_end)
131    {
132        if (*p == 0x0f)
133        {
134            if (p + 6 <= p_end)
135            {
136                len = AV_RB16(p + 4);
137
138                if (p + len + 6 <= p_end)
139                {
140                    *poutbuf_size += len + 6;
141
142                    p += len + 6;
143                } else
144                    break;
145            } else
146                break;
147        } else if (*p == 0xff) {
148            if (p + 1 < p_end)
149            {
150                dprintf(avctx, "Junk at end of packet\n");
151            }
152            pc->packet_index = p - pc->packet_buf;
153            pc->in_packet = 0;
154            break;
155        } else {
156            av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
157
158            pc->packet_index = p - pc->packet_buf;
159            pc->in_packet = 0;
160            break;
161        }
162    }
163
164    if (*poutbuf_size > 0)
165    {
166        *poutbuf = pc->packet_buf;
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 dvbsub_parser = {
183    { CODEC_ID_DVB_SUBTITLE },
184    sizeof(DVBSubParseContext),
185    dvbsub_parse_init,
186    dvbsub_parse,
187    dvbsub_parse_close,
188};
189