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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 
00025 #include "parser.h"
00026 #include "dca.h"
00027 
00028 typedef struct DCAParseContext {
00029     ParseContext pc;
00030     uint32_t lastmarker;
00031     int size;
00032     int framesize;
00033     int hd_pos;
00034 } DCAParseContext;
00035 
00036 #define IS_MARKER(state, i, buf, buf_size) \
00037  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
00038  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
00039  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)
00040 
00045 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
00046                               int buf_size)
00047 {
00048     int start_found, i;
00049     uint32_t state;
00050     ParseContext *pc = &pc1->pc;
00051 
00052     start_found = pc->frame_start_found;
00053     state = pc->state;
00054 
00055     i = 0;
00056     if (!start_found) {
00057         for (i = 0; i < buf_size; i++) {
00058             state = (state << 8) | buf[i];
00059             if (IS_MARKER(state, i, buf, buf_size)) {
00060                 if (pc1->lastmarker && state == pc1->lastmarker) {
00061                     start_found = 1;
00062                     break;
00063                 } else if (!pc1->lastmarker) {
00064                     start_found = 1;
00065                     pc1->lastmarker = state;
00066                     break;
00067                 }
00068             }
00069         }
00070     }
00071     if (start_found) {
00072         for (; i < buf_size; i++) {
00073             pc1->size++;
00074             state = (state << 8) | buf[i];
00075             if (state == DCA_HD_MARKER && !pc1->hd_pos)
00076                 pc1->hd_pos = pc1->size;
00077             if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size)) {
00078                 if(pc1->framesize > pc1->size)
00079                     continue;
00080                 if(!pc1->framesize){
00081                     pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
00082                 }
00083                 pc->frame_start_found = 0;
00084                 pc->state = -1;
00085                 pc1->size = 0;
00086                 return i - 3;
00087             }
00088         }
00089     }
00090     pc->frame_start_found = start_found;
00091     pc->state = state;
00092     return END_NOT_FOUND;
00093 }
00094 
00095 static av_cold int dca_parse_init(AVCodecParserContext * s)
00096 {
00097     DCAParseContext *pc1 = s->priv_data;
00098 
00099     pc1->lastmarker = 0;
00100     return 0;
00101 }
00102 
00103 static int dca_parse(AVCodecParserContext * s,
00104                      AVCodecContext * avctx,
00105                      const uint8_t ** poutbuf, int *poutbuf_size,
00106                      const uint8_t * buf, int buf_size)
00107 {
00108     DCAParseContext *pc1 = s->priv_data;
00109     ParseContext *pc = &pc1->pc;
00110     int next;
00111 
00112     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
00113         next = buf_size;
00114     } else {
00115         next = dca_find_frame_end(pc1, buf, buf_size);
00116 
00117         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00118             *poutbuf = NULL;
00119             *poutbuf_size = 0;
00120             return buf_size;
00121         }
00122     }
00123     *poutbuf = buf;
00124     *poutbuf_size = buf_size;
00125     return next;
00126 }
00127 
00128 AVCodecParser dca_parser = {
00129     {CODEC_ID_DTS},
00130     sizeof(DCAParseContext),
00131     dca_parse_init,
00132     dca_parse,
00133     ff_parse_close,
00134 };

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