0a83de39ef0af79162f97fede26455fd1437fda2
[ffmpeg.git] / 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 #include "avcodec.h"
22 #include "dsputil.h"
23 #include "bitstream.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 */
34 typedef struct DVBSubParseContext {
35     uint8_t *packet_buf;
36     int packet_start;
37     int packet_index;
38     int in_packet;
39 } DVBSubParseContext;
40
41 static 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
49 static 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 #ifdef DEBUG
59     av_log(avctx, AV_LOG_INFO, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
60             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
61 #endif
62
63 #ifdef DEBUG_PACKET_CONTENTS
64     int i;
65
66     for (i=0; i < buf_size; i++)
67     {
68         av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
69         if (i % 16 == 15)
70             av_log(avctx, AV_LOG_INFO, "\n");
71     }
72
73     if (i % 16 != 0)
74         av_log(avctx, AV_LOG_INFO, "\n");
75
76 #endif
77
78     *poutbuf = NULL;
79     *poutbuf_size = 0;
80
81     s->fetch_timestamp = 1;
82
83     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
84     {
85         if (pc->packet_index != pc->packet_start)
86         {
87 #ifdef DEBUG
88             av_log(avctx, AV_LOG_INFO, "Discarding %d bytes\n",
89                 pc->packet_index - pc->packet_start);
90 #endif
91         }
92
93         pc->packet_start = 0;
94         pc->packet_index = 0;
95
96         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
97 #ifdef DEBUG
98             av_log(avctx, AV_LOG_INFO, "Bad packet header\n");
99 #endif
100             return -1;
101         }
102
103         buf_pos = 2;
104
105         pc->in_packet = 1;
106     } else {
107         if (pc->packet_start != 0)
108         {
109             if (pc->packet_index != pc->packet_start)
110             {
111                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
112                             pc->packet_index - pc->packet_start);
113
114                 pc->packet_index -= pc->packet_start;
115                 pc->packet_start = 0;
116             } else {
117                 pc->packet_start = 0;
118                 pc->packet_index = 0;
119             }
120         }
121     }
122
123     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
124         return -1;
125
126 /* if not currently in a packet, discard data */
127     if (pc->in_packet == 0)
128         return buf_size;
129
130     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
131     pc->packet_index += buf_size - buf_pos;
132
133     p = pc->packet_buf;
134     p_end = pc->packet_buf + pc->packet_index;
135
136     while (p < p_end)
137     {
138         if (*p == 0x0f)
139         {
140             if (p + 6 <= p_end)
141             {
142                 len = AV_RB16(p + 4);
143
144                 if (p + len + 6 <= p_end)
145                 {
146                     *poutbuf_size += len + 6;
147
148                     p += len + 6;
149                 } else
150                     break;
151             } else
152                 break;
153         } else if (*p == 0xff) {
154             if (p + 1 < p_end)
155             {
156 #ifdef DEBUG
157                 av_log(avctx, AV_LOG_INFO, "Junk at end of packet\n");
158 #endif
159             }
160             pc->packet_index = p - pc->packet_buf;
161             pc->in_packet = 0;
162             break;
163         } else {
164             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
165
166             pc->packet_index = p - pc->packet_buf;
167             pc->in_packet = 0;
168             break;
169         }
170     }
171
172     if (*poutbuf_size > 0)
173     {
174         *poutbuf = pc->packet_buf;
175         pc->packet_start = *poutbuf_size;
176     }
177
178     if (s->pts == AV_NOPTS_VALUE)
179         s->pts = s->last_pts;
180
181     return buf_size;
182 }
183
184 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
185 {
186     DVBSubParseContext *pc = s->priv_data;
187     av_freep(&pc->packet_buf);
188 }
189
190 AVCodecParser dvbsub_parser = {
191     { CODEC_ID_DVB_SUBTITLE },
192     sizeof(DVBSubParseContext),
193     dvbsub_parse_init,
194     dvbsub_parse,
195     dvbsub_parse_close,
196 };