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 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 } DCAParseContext;
  38
  39 #define IS_MARKER(state, i, buf, buf_size) \
  40  ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
  41  || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
  42  || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)
  43
  44 /**
  45  * finds the end of the current frame in the bitstream.
  46  * @return the position of the first byte of the next frame, or -1
  47  */
  48 static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
  49                               int buf_size)
  50 {
  51     int start_found, i;
  52     uint32_t state;
  53     ParseContext *pc = &pc1->pc;
  54
  55     start_found = pc->frame_start_found;
  56     state = pc->state;
  57
  58     i = 0;
  59     if (!start_found) {
  60         for (i = 0; i < buf_size; i++) {
  61             state = (state << 8) | buf[i];
  62             if (IS_MARKER(state, i, buf, buf_size)) {
  63                 if (pc1->lastmarker && state == pc1->lastmarker) {
  64                     start_found = 1;
  65                     break;
  66                 } else if (!pc1->lastmarker) {
  67                     start_found = 1;
  68                     pc1->lastmarker = state;
  69                     break;
  70                 }
  71             }
  72         }
  73     }
  74     if (start_found) {
  75         for (; i < buf_size; i++) {
  76             pc1->size++;
  77             state = (state << 8) | buf[i];
  78             if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size) && (!pc1->framesize || pc1->framesize == pc1->size)) {
  79                 pc->frame_start_found = 0;
  80                 pc->state = -1;
  81                 pc1->framesize = pc1->size;
  82                 pc1->size = 0;
  83                 return i - 3;
  84             }
  85         }
  86     }
  87     pc->frame_start_found = start_found;
  88     pc->state = state;
  89     return END_NOT_FOUND;
  90 }
  91
  92 static av_cold int dca_parse_init(AVCodecParserContext * s)
  93 {
  94     DCAParseContext *pc1 = s->priv_data;
  95
  96     pc1->lastmarker = 0;
  97     return 0;
  98 }
  99
 100 static int dca_parse(AVCodecParserContext * s,
 101                      AVCodecContext * avctx,
 102                      const uint8_t ** poutbuf, int *poutbuf_size,
 103                      const uint8_t * buf, int buf_size)
 104 {
 105     DCAParseContext *pc1 = s->priv_data;
 106     ParseContext *pc = &pc1->pc;
 107     int next;
 108
 109     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 110         next = buf_size;
 111     } else {
 112         next = dca_find_frame_end(pc1, buf, buf_size);
 113
 114         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 115             *poutbuf = NULL;
 116             *poutbuf_size = 0;
 117             return buf_size;
 118         }
 119     }
 120     *poutbuf = buf;
 121     *poutbuf_size = buf_size;
 122     return next;
 123 }
 124
 125 AVCodecParser dca_parser = {
 126     {CODEC_ID_DTS},
 127     sizeof(DCAParseContext),
 128     dca_parse_init,
 129     dca_parse,
 130     ff_parse_close,
 131 };