libavcodec/dca_parser.c

   1 /*
   2  * DCA parser
   3  * Copyright (C) 2004 Gildas Bazin
   4  * Copyright (C) 2004 Benjamin Zores
   5  * Copyright (C) 2006 Benjamin Larsson
   6  * Copyright (C) 2007 Konstantin Shishkov
   7  *
   8  * This file is part of FFmpeg.
   9  *
  10  * FFmpeg is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * FFmpeg is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with FFmpeg; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 /**
  26  * @file libavcodec/dca_parser.c
  27  */
  28
  29 #include "parser.h"
  30 #include "dca.h"
  31
  32 typedef struct DCAParseContext {
  33     ParseContext pc;
  34     uint32_t lastmarker;
  35     int size;
  36     int framesize;
  37     int hd_pos;
  38 } DCAParseContext;
  39
  40 #define IS_MARKER(state, i, buf, buf_size) \
  41  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
  42  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
  43  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)
  44
  45 /**
  46  * finds the end of the current frame in the bitstream.
  47  * @return the position of the first byte of the next frame, or -1
  48  */
  49 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
  50                               int buf_size)
  51 {
  52     int start_found, i;
  53     uint32_t state;
  54     ParseContext *pc = &pc1->pc;
  55
  56     start_found = pc->frame_start_found;
  57     state = pc->state;
  58
  59     i = 0;
  60     if (!start_found) {
  61         for (i = 0; i < buf_size; i++) {
  62             state = (state << 8) | buf[i];
  63             if (IS_MARKER(state, i, buf, buf_size)) {
  64                 if (pc1->lastmarker && state == pc1->lastmarker) {
  65                     start_found = 1;
  66                     break;
  67                 } else if (!pc1->lastmarker) {
  68                     start_found = 1;
  69                     pc1->lastmarker = state;
  70                     break;
  71                 }
  72             }
  73         }
  74     }
  75     if (start_found) {
  76         for (; i < buf_size; i++) {
  77             pc1->size++;
  78             state = (state << 8) | buf[i];
  79             if (state == DCA_HD_MARKER && !pc1->hd_pos)
  80                 pc1->hd_pos = pc1->size;
  81             if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size)) {
  82                 if(pc1->framesize > pc1->size)
  83                     continue;
  84                 if(!pc1->framesize){
  85                     pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
  86                 }
  87                 pc->frame_start_found = 0;
  88                 pc->state = -1;
  89                 pc1->size = 0;
  90                 return i - 3;
  91             }
  92         }
  93     }
  94     pc->frame_start_found = start_found;
  95     pc->state = state;
  96     return END_NOT_FOUND;
  97 }
  98
  99 static av_cold int dca_parse_init(AVCodecParserContext * s)
 100 {
 101     DCAParseContext *pc1 = s->priv_data;
 102
 103     pc1->lastmarker = 0;
 104     return 0;
 105 }
 106
 107 static int dca_parse(AVCodecParserContext * s,
 108                      AVCodecContext * avctx,
 109                      const uint8_t ** poutbuf, int *poutbuf_size,
 110                      const uint8_t * buf, int buf_size)
 111 {
 112     DCAParseContext *pc1 = s->priv_data;
 113     ParseContext *pc = &pc1->pc;
 114     int next;
 115
 116     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 117         next = buf_size;
 118     } else {
 119         next = dca_find_frame_end(pc1, buf, buf_size);
 120
 121         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 122             *poutbuf = NULL;
 123             *poutbuf_size = 0;
 124             return buf_size;
 125         }
 126     }
 127     *poutbuf = buf;
 128     *poutbuf_size = buf_size;
 129     return next;
 130 }
 131
 132 AVCodecParser dca_parser = {
 133     {CODEC_ID_DTS},
 134     sizeof(DCAParseContext),
 135     dca_parse_init,
 136     dca_parse,
 137     ff_parse_close,
 138 };