aac_common.c

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18 /*
  19  * based in parts on libfaad, Copyright (C) 2003-2005 M. Bakker,
  20  * Ahead Software AG
  21  */
  22
  23 /** \file aac_ccomon.c common functions of aac_afh and aadcec */
  24
  25 #include "para.h"
  26 #include "aac.h"
  27 #include "error.h"
  28
  29 /**
  30  * get a new libfaad decoder handle
  31  *
  32  */
  33 NeAACDecHandle aac_open(void)
  34 {
  35         NeAACDecHandle h = NeAACDecOpen();
  36         NeAACDecConfigurationPtr c = NeAACDecGetCurrentConfiguration(h);
  37
  38         c->defObjectType = LC;
  39         c->outputFormat = FAAD_FMT_16BIT;
  40         c->downMatrix = 0;
  41         NeAACDecSetConfiguration(h, c);
  42         return h;
  43 };
  44
  45 static int aac_read_decoder_length(unsigned char *buf, int *description_len)
  46 {
  47         uint8_t b;
  48         uint8_t numBytes = 0;
  49         uint32_t length = 0;
  50
  51         do {
  52                 b = buf[numBytes];
  53                 numBytes++;
  54                 length = (length << 7) | (b & 0x7F);
  55         } while
  56                 ((b & 0x80) && numBytes < 4);
  57         *description_len = numBytes;
  58         return length;
  59 }
  60
  61 int aac_find_esds(unsigned char *buf, unsigned buflen, int *skip)
  62 {
  63         int i;
  64
  65         for (i = 0; i + 4 < buflen; i++) {
  66                 unsigned char *p = buf + i;
  67                 int decoder_length, description_len;
  68
  69                 if (p[0] != 'e' || p[1] != 's' || p[2] != 'd' || p[3] != 's')
  70                         continue;
  71                 i += 8;
  72                 p = buf + i;
  73                 PARA_INFO_LOG("found esds@%d, next: %x\n", i, *p);
  74                 if (*p == 3)
  75                         i += 8;
  76                 else
  77                         i += 6;
  78                 p = buf + i;
  79                 PARA_INFO_LOG("next: %x\n", *p);
  80                 if (*p != 4)
  81                         continue;
  82                 i += 18;
  83                 p = buf + i;
  84                 PARA_INFO_LOG("next: %x\n", *p);
  85                 if (*p != 5)
  86                         continue;
  87                 i++;
  88                 p = buf + i;
  89                 decoder_length = aac_read_decoder_length(p, &description_len);
  90                 PARA_INFO_LOG("decoder length: %d\n", decoder_length);
  91                 i += description_len;
  92                 *skip = i;
  93                 return decoder_length;
  94         }
  95         return -E_ESDS;
  96 }
  97
  98 unsigned aac_read_int32(unsigned char *buf)
  99 {
 100         uint8_t *d = (uint8_t*)buf;
 101         return (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
 102 }
 103
 104 /**
 105  * search for the first entry in the stco table
 106  *
 107  * \param buf buffer to seach
 108  * \param buflen length of \a buf
 109  * \param skip Upon succesful return, this contains the number
 110  * of bytes to skip from the input buffer.
 111  *
 112  * \return the position of the first entry in the table on success,
 113  * -E_STCO on errors.
 114  */
 115
 116 int aac_find_entry_point(unsigned char *buf, unsigned buflen, int *skip)
 117 {
 118         int i, ret;
 119
 120         for (i = 0; i + 20 < buflen; i++) {
 121                 unsigned char *p = buf + i;
 122
 123                 if (p[0] != 's' || p[1] != 't' || p[2] != 'c' || p[3] != 'o')
 124                         continue;
 125                 PARA_INFO_LOG("found stco@%d\n", i);
 126                 i += 12;
 127                 ret = aac_read_int32(buf + i); /* first offset */
 128                 i += 4;
 129                 PARA_INFO_LOG("num entries: %d\n", ret);
 130                 *skip = i;
 131                 return ret;
 132         }
 133         PARA_WARNING_LOG("stco not found, buflen: %d\n", buflen);
 134         return -E_STCO;
 135 }
 136