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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 "bitstream.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 #ifdef DEBUG
00059     av_log(avctx, AV_LOG_INFO, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
00060             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
00061 #endif
00062 
00063 #ifdef DEBUG_PACKET_CONTENTS
00064     int i;
00065 
00066     for (i=0; i < buf_size; i++)
00067     {
00068         av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
00069         if (i % 16 == 15)
00070             av_log(avctx, AV_LOG_INFO, "\n");
00071     }
00072 
00073     if (i % 16 != 0)
00074         av_log(avctx, AV_LOG_INFO, "\n");
00075 
00076 #endif
00077 
00078     *poutbuf = NULL;
00079     *poutbuf_size = 0;
00080 
00081     s->fetch_timestamp = 1;
00082 
00083     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
00084     {
00085         if (pc->packet_index != pc->packet_start)
00086         {
00087 #ifdef DEBUG
00088             av_log(avctx, AV_LOG_INFO, "Discarding %d bytes\n",
00089                 pc->packet_index - pc->packet_start);
00090 #endif
00091         }
00092 
00093         pc->packet_start = 0;
00094         pc->packet_index = 0;
00095 
00096         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
00097 #ifdef DEBUG
00098             av_log(avctx, AV_LOG_INFO, "Bad packet header\n");
00099 #endif
00100             return -1;
00101         }
00102 
00103         buf_pos = 2;
00104 
00105         pc->in_packet = 1;
00106     } else {
00107         if (pc->packet_start != 0)
00108         {
00109             if (pc->packet_index != pc->packet_start)
00110             {
00111                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
00112                             pc->packet_index - pc->packet_start);
00113 
00114                 pc->packet_index -= pc->packet_start;
00115                 pc->packet_start = 0;
00116             } else {
00117                 pc->packet_start = 0;
00118                 pc->packet_index = 0;
00119             }
00120         }
00121     }
00122 
00123     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
00124         return -1;
00125 
00126 /* if not currently in a packet, discard data */
00127     if (pc->in_packet == 0)
00128         return buf_size;
00129 
00130     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
00131     pc->packet_index += buf_size - buf_pos;
00132 
00133     p = pc->packet_buf;
00134     p_end = pc->packet_buf + pc->packet_index;
00135 
00136     while (p < p_end)
00137     {
00138         if (*p == 0x0f)
00139         {
00140             if (p + 6 <= p_end)
00141             {
00142                 len = AV_RB16(p + 4);
00143 
00144                 if (p + len + 6 <= p_end)
00145                 {
00146                     *poutbuf_size += len + 6;
00147 
00148                     p += len + 6;
00149                 } else
00150                     break;
00151             } else
00152                 break;
00153         } else if (*p == 0xff) {
00154             if (p + 1 < p_end)
00155             {
00156 #ifdef DEBUG
00157                 av_log(avctx, AV_LOG_INFO, "Junk at end of packet\n");
00158 #endif
00159             }
00160             pc->packet_index = p - pc->packet_buf;
00161             pc->in_packet = 0;
00162             break;
00163         } else {
00164             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
00165 
00166             pc->packet_index = p - pc->packet_buf;
00167             pc->in_packet = 0;
00168             break;
00169         }
00170     }
00171 
00172     if (*poutbuf_size > 0)
00173     {
00174         *poutbuf = pc->packet_buf;
00175         pc->packet_start = *poutbuf_size;
00176     }
00177 
00178     if (s->pts == AV_NOPTS_VALUE)
00179         s->pts = s->last_pts;
00180 
00181     return buf_size;
00182 }
00183 
00184 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
00185 {
00186     DVBSubParseContext *pc = s->priv_data;
00187     av_freep(&pc->packet_buf);
00188 }
00189 
00190 AVCodecParser dvbsub_parser = {
00191     { CODEC_ID_DVB_SUBTITLE },
00192     sizeof(DVBSubParseContext),
00193     dvbsub_parse_init,
00194     dvbsub_parse,
00195     dvbsub_parse_close,
00196 };

Generated on Tue Nov 4 2014 12:59:21 for ffmpeg by  doxygen 1.7.1