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libavcodec/dca_parser.c

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00001 /*
00002  * DCA parser
00003  * Copyright (C) 2004 Gildas Bazin
00004  * Copyright (C) 2004 Benjamin Zores
00005  * Copyright (C) 2006 Benjamin Larsson
00006  * Copyright (C) 2007 Konstantin Shishkov
00007  *
00008  * This file is part of FFmpeg.
00009  *
00010  * FFmpeg is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * FFmpeg is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with FFmpeg; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 
00029 #include "parser.h"
00030 #include "dca.h"
00031 
00032 typedef struct DCAParseContext {
00033     ParseContext pc;
00034     uint32_t lastmarker;
00035     int size;
00036     int framesize;
00037     int hd_pos;
00038 } DCAParseContext;
00039 
00040 #define IS_MARKER(state, i, buf, buf_size) \
00041  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
00042  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
00043  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)
00044 
00049 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
00050                               int buf_size)
00051 {
00052     int start_found, i;
00053     uint32_t state;
00054     ParseContext *pc = &pc1->pc;
00055 
00056     start_found = pc->frame_start_found;
00057     state = pc->state;
00058 
00059     i = 0;
00060     if (!start_found) {
00061         for (i = 0; i < buf_size; i++) {
00062             state = (state << 8) | buf[i];
00063             if (IS_MARKER(state, i, buf, buf_size)) {
00064                 if (pc1->lastmarker && state == pc1->lastmarker) {
00065                     start_found = 1;
00066                     break;
00067                 } else if (!pc1->lastmarker) {
00068                     start_found = 1;
00069                     pc1->lastmarker = state;
00070                     break;
00071                 }
00072             }
00073         }
00074     }
00075     if (start_found) {
00076         for (; i < buf_size; i++) {
00077             pc1->size++;
00078             state = (state << 8) | buf[i];
00079             if (state == DCA_HD_MARKER && !pc1->hd_pos)
00080                 pc1->hd_pos = pc1->size;
00081             if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size)) {
00082                 if(pc1->framesize > pc1->size)
00083                     continue;
00084                 if(!pc1->framesize){
00085                     pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
00086                 }
00087                 pc->frame_start_found = 0;
00088                 pc->state = -1;
00089                 pc1->size = 0;
00090                 return i - 3;
00091             }
00092         }
00093     }
00094     pc->frame_start_found = start_found;
00095     pc->state = state;
00096     return END_NOT_FOUND;
00097 }
00098 
00099 static av_cold int dca_parse_init(AVCodecParserContext * s)
00100 {
00101     DCAParseContext *pc1 = s->priv_data;
00102 
00103     pc1->lastmarker = 0;
00104     return 0;
00105 }
00106 
00107 static int dca_parse(AVCodecParserContext * s,
00108                      AVCodecContext * avctx,
00109                      const uint8_t ** poutbuf, int *poutbuf_size,
00110                      const uint8_t * buf, int buf_size)
00111 {
00112     DCAParseContext *pc1 = s->priv_data;
00113     ParseContext *pc = &pc1->pc;
00114     int next;
00115 
00116     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
00117         next = buf_size;
00118     } else {
00119         next = dca_find_frame_end(pc1, buf, buf_size);
00120 
00121         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00122             *poutbuf = NULL;
00123             *poutbuf_size = 0;
00124             return buf_size;
00125         }
00126     }
00127     *poutbuf = buf;
00128     *poutbuf_size = buf_size;
00129     return next;
00130 }
00131 
00132 AVCodecParser dca_parser = {
00133     {CODEC_ID_DTS},
00134     sizeof(DCAParseContext),
00135     dca_parse_init,
00136     dca_parse,
00137     ff_parse_close,
00138 };

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