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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 //#define DEBUG
00026 //#define DEBUG_PACKET_CONTENTS
00027 
00028 /* Parser (mostly) copied from dvdsub.c */
00029 
00030 #define PARSE_BUF_SIZE  (65536)
00031 
00032 
00033 /* parser definition */
00034 typedef struct DVBSubParseContext {
00035     uint8_t *packet_buf;
00036     int packet_start;
00037     int packet_index;
00038     int in_packet;
00039 } DVBSubParseContext;
00040 
00041 static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
00042 {
00043     DVBSubParseContext *pc = s->priv_data;
00044     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
00045 
00046     return 0;
00047 }
00048 
00049 static int dvbsub_parse(AVCodecParserContext *s,
00050                         AVCodecContext *avctx,
00051                         const uint8_t **poutbuf, int *poutbuf_size,
00052                         const uint8_t *buf, int buf_size)
00053 {
00054     DVBSubParseContext *pc = s->priv_data;
00055     uint8_t *p, *p_end;
00056     int len, buf_pos = 0;
00057 
00058     dprintf(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
00059             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
00060 
00061 #ifdef DEBUG_PACKET_CONTENTS
00062     int i;
00063 
00064     for (i=0; i < buf_size; i++)
00065     {
00066         av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
00067         if (i % 16 == 15)
00068             av_log(avctx, AV_LOG_INFO, "\n");
00069     }
00070 
00071     if (i % 16 != 0)
00072         av_log(avctx, AV_LOG_INFO, "\n");
00073 
00074 #endif
00075 
00076     *poutbuf = NULL;
00077     *poutbuf_size = 0;
00078 
00079     s->fetch_timestamp = 1;
00080 
00081     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
00082     {
00083         if (pc->packet_index != pc->packet_start)
00084         {
00085             dprintf(avctx, "Discarding %d bytes\n",
00086                     pc->packet_index - pc->packet_start);
00087         }
00088 
00089         pc->packet_start = 0;
00090         pc->packet_index = 0;
00091 
00092         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
00093             dprintf(avctx, "Bad packet header\n");
00094             return -1;
00095         }
00096 
00097         buf_pos = 2;
00098 
00099         pc->in_packet = 1;
00100     } else {
00101         if (pc->packet_start != 0)
00102         {
00103             if (pc->packet_index != pc->packet_start)
00104             {
00105                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
00106                             pc->packet_index - pc->packet_start);
00107 
00108                 pc->packet_index -= pc->packet_start;
00109                 pc->packet_start = 0;
00110             } else {
00111                 pc->packet_start = 0;
00112                 pc->packet_index = 0;
00113             }
00114         }
00115     }
00116 
00117     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
00118         return -1;
00119 
00120 /* if not currently in a packet, discard data */
00121     if (pc->in_packet == 0)
00122         return buf_size;
00123 
00124     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
00125     pc->packet_index += buf_size - buf_pos;
00126 
00127     p = pc->packet_buf;
00128     p_end = pc->packet_buf + pc->packet_index;
00129 
00130     while (p < p_end)
00131     {
00132         if (*p == 0x0f)
00133         {
00134             if (p + 6 <= p_end)
00135             {
00136                 len = AV_RB16(p + 4);
00137 
00138                 if (p + len + 6 <= p_end)
00139                 {
00140                     *poutbuf_size += len + 6;
00141 
00142                     p += len + 6;
00143                 } else
00144                     break;
00145             } else
00146                 break;
00147         } else if (*p == 0xff) {
00148             if (p + 1 < p_end)
00149             {
00150                 dprintf(avctx, "Junk at end of packet\n");
00151             }
00152             pc->packet_index = p - pc->packet_buf;
00153             pc->in_packet = 0;
00154             break;
00155         } else {
00156             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
00157 
00158             pc->packet_index = p - pc->packet_buf;
00159             pc->in_packet = 0;
00160             break;
00161         }
00162     }
00163 
00164     if (*poutbuf_size > 0)
00165     {
00166         *poutbuf = pc->packet_buf;
00167         pc->packet_start = *poutbuf_size;
00168     }
00169 
00170     if (s->pts == AV_NOPTS_VALUE)
00171         s->pts = s->last_pts;
00172 
00173     return buf_size;
00174 }
00175 
00176 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
00177 {
00178     DVBSubParseContext *pc = s->priv_data;
00179     av_freep(&pc->packet_buf);
00180 }
00181 
00182 AVCodecParser dvbsub_parser = {
00183     { CODEC_ID_DVB_SUBTITLE },
00184     sizeof(DVBSubParseContext),
00185     dvbsub_parse_init,
00186     dvbsub_parse,
00187     dvbsub_parse_close,
00188 };

Generated on Fri Sep 16 2011 17:17:35 for FFmpeg by  doxygen 1.7.1