libavcodec/dvbsub_parser.c
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00001 /*
00002  * DVB subtitle parser for FFmpeg
00003  * Copyright (c) 2005 Ian Caulfield
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "avcodec.h"
00022 #include "dsputil.h"
00023 #include "get_bits.h"
00024 
00025 /* Parser (mostly) copied from dvdsub.c */
00026 
00027 #define PARSE_BUF_SIZE  (65536)
00028 
00029 
00030 /* parser definition */
00031 typedef struct DVBSubParseContext {
00032     uint8_t *packet_buf;
00033     int packet_start;
00034     int packet_index;
00035     int in_packet;
00036 } DVBSubParseContext;
00037 
00038 static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
00039 {
00040     DVBSubParseContext *pc = s->priv_data;
00041     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
00042 
00043     return 0;
00044 }
00045 
00046 static int dvbsub_parse(AVCodecParserContext *s,
00047                         AVCodecContext *avctx,
00048                         const uint8_t **poutbuf, int *poutbuf_size,
00049                         const uint8_t *buf, int buf_size)
00050 {
00051     DVBSubParseContext *pc = s->priv_data;
00052     uint8_t *p, *p_end;
00053     int i, len, buf_pos = 0;
00054 
00055     av_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
00056             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
00057 
00058     for (i=0; i < buf_size; i++)
00059     {
00060         av_dlog(avctx, "%02x ", buf[i]);
00061         if (i % 16 == 15)
00062             av_dlog(avctx, "\n");
00063     }
00064 
00065     if (i % 16 != 0)
00066         av_dlog(avctx, "\n");
00067 
00068     *poutbuf = NULL;
00069     *poutbuf_size = 0;
00070 
00071     s->fetch_timestamp = 1;
00072 
00073     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
00074     {
00075         if (pc->packet_index != pc->packet_start)
00076         {
00077             av_dlog(avctx, "Discarding %d bytes\n",
00078                     pc->packet_index - pc->packet_start);
00079         }
00080 
00081         pc->packet_start = 0;
00082         pc->packet_index = 0;
00083 
00084         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
00085             av_dlog(avctx, "Bad packet header\n");
00086             return -1;
00087         }
00088 
00089         buf_pos = 2;
00090 
00091         pc->in_packet = 1;
00092     } else {
00093         if (pc->packet_start != 0)
00094         {
00095             if (pc->packet_index != pc->packet_start)
00096             {
00097                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
00098                             pc->packet_index - pc->packet_start);
00099 
00100                 pc->packet_index -= pc->packet_start;
00101                 pc->packet_start = 0;
00102             } else {
00103                 pc->packet_start = 0;
00104                 pc->packet_index = 0;
00105             }
00106         }
00107     }
00108 
00109     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
00110         return -1;
00111 
00112 /* if not currently in a packet, discard data */
00113     if (pc->in_packet == 0)
00114         return buf_size;
00115 
00116     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
00117     pc->packet_index += buf_size - buf_pos;
00118 
00119     p = pc->packet_buf;
00120     p_end = pc->packet_buf + pc->packet_index;
00121 
00122     while (p < p_end)
00123     {
00124         if (*p == 0x0f)
00125         {
00126             if (p + 6 <= p_end)
00127             {
00128                 len = AV_RB16(p + 4);
00129 
00130                 if (p + len + 6 <= p_end)
00131                 {
00132                     *poutbuf_size += len + 6;
00133 
00134                     p += len + 6;
00135                 } else
00136                     break;
00137             } else
00138                 break;
00139         } else if (*p == 0xff) {
00140             if (p + 1 < p_end)
00141             {
00142                 av_dlog(avctx, "Junk at end of packet\n");
00143             }
00144             pc->packet_index = p - pc->packet_buf;
00145             pc->in_packet = 0;
00146             break;
00147         } else {
00148             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
00149 
00150             pc->packet_index = p - pc->packet_buf;
00151             pc->in_packet = 0;
00152             break;
00153         }
00154     }
00155 
00156     if (*poutbuf_size > 0)
00157     {
00158         *poutbuf = pc->packet_buf;
00159         pc->packet_start = *poutbuf_size;
00160     }
00161 
00162     if (s->pts == AV_NOPTS_VALUE)
00163         s->pts = s->last_pts;
00164 
00165     return buf_size;
00166 }
00167 
00168 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
00169 {
00170     DVBSubParseContext *pc = s->priv_data;
00171     av_freep(&pc->packet_buf);
00172 }
00173 
00174 AVCodecParser ff_dvbsub_parser = {
00175     .codec_ids      = { CODEC_ID_DVB_SUBTITLE },
00176     .priv_data_size = sizeof(DVBSubParseContext),
00177     .parser_init    = dvbsub_parse_init,
00178     .parser_parse   = dvbsub_parse,
00179     .parser_close   = dvbsub_parse_close,
00180 };