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_common.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 /**
  62  * search for the position and the length of the decoder configuration
  63  *
  64  * \param buf buffer to seach
  65  * \param buflen length of \a buf
  66  * \param skip Upon succesful return, this contains the offset in \a buf where
  67  * the decoder config starts.
  68  *
  69  * \return The length of the decoder configuration
  70  */
  71 ssize_t aac_find_esds(unsigned char *buf, size_t buflen, size_t *skip)
  72 {
  73         size_t i;
  74
  75         for (i = 0; i + 4 < buflen; i++) {
  76                 unsigned char *p = buf + i;
  77                 int decoder_length, description_len;
  78
  79                 if (p[0] != 'e' || p[1] != 's' || p[2] != 'd' || p[3] != 's')
  80                         continue;
  81                 i += 8;
  82                 p = buf + i;
  83                 PARA_INFO_LOG("found esds@%zu, next: %x\n", i, *p);
  84                 if (*p == 3)
  85                         i += 8;
  86                 else
  87                         i += 6;
  88                 p = buf + i;
  89                 PARA_INFO_LOG("next: %x\n", *p);
  90                 if (*p != 4)
  91                         continue;
  92                 i += 18;
  93                 p = buf + i;
  94                 PARA_INFO_LOG("next: %x\n", *p);
  95                 if (*p != 5)
  96                         continue;
  97                 i++;
  98                 p = buf + i;
  99                 decoder_length = aac_read_decoder_length(p, &description_len);
 100                 PARA_INFO_LOG("decoder length: %d\n", decoder_length);
 101                 i += description_len;
 102                 *skip = i;
 103                 return decoder_length;
 104         }
 105         return -E_ESDS;
 106 }
 107
 108 /**
 109  * search for the first entry in the stco table
 110  *
 111  * \param buf buffer to seach
 112  * \param buflen length of \a buf
 113  * \param skip Upon succesful return, this contains the number
 114  * of bytes to skip from the input buffer.
 115  *
 116  * \return the position of the first entry in the table on success,
 117  * -E_STCO on errors.
 118  */
 119 ssize_t aac_find_entry_point(unsigned char *buf, size_t buflen, size_t *skip)
 120 {
 121         ssize_t ret;
 122         size_t i;
 123
 124         for (i = 0; i + 20 < buflen; i++) {
 125                 unsigned char *p = buf + i;
 126
 127                 if (p[0] != 's' || p[1] != 't' || p[2] != 'c' || p[3] != 'o')
 128                         continue;
 129                 PARA_INFO_LOG("found stco@%zu\n", i);
 130                 i += 12;
 131                 ret = aac_read_int32(buf + i); /* first offset */
 132                 i += 4;
 133                 PARA_INFO_LOG("num entries: %zd\n", ret);
 134                 *skip = i;
 135                 return ret;
 136         }
 137         PARA_WARNING_LOG("stco not found, buflen: %zu\n", buflen);
 138         return -E_STCO;
 139 }