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 NeAACDecHandle aac_open(void)
  30 {
  31         NeAACDecHandle h = NeAACDecOpen();
  32         NeAACDecConfigurationPtr c = NeAACDecGetCurrentConfiguration(h);
  33
  34         c->defObjectType = LC;
  35         c->outputFormat = FAAD_FMT_16BIT;
  36         c->downMatrix = 0;
  37         NeAACDecSetConfiguration(h, c);
  38         return h;
  39 };
  40
  41 static int aac_read_decoder_length(unsigned char *buf, int *description_len)
  42 {
  43         uint8_t b;
  44         uint8_t numBytes = 0;
  45         uint32_t length = 0;
  46
  47         do {
  48                 b = buf[numBytes];
  49                 numBytes++;
  50                 length = (length << 7) | (b & 0x7F);
  51         } while
  52                 ((b & 0x80) && numBytes < 4);
  53         *description_len = numBytes;
  54         return length;
  55 }
  56
  57 int aac_find_esds(unsigned char *buf, unsigned buflen, int *skip)
  58 {
  59         int i;
  60
  61         for (i = 0; i + 4 < buflen; i++) {
  62                 unsigned char *p = buf + i;
  63                 int decoder_length, description_len;
  64
  65                 if (p[0] != 'e' || p[1] != 's' || p[2] != 'd' || p[3] != 's')
  66                         continue;
  67                 i += 8;
  68                 p = buf + i;
  69                 PARA_INFO_LOG("found esds@%d, next: %x\n", i, *p);
  70                 if (*p == 3)
  71                         i += 8;
  72                 else
  73                         i += 6;
  74                 p = buf + i;
  75                 PARA_INFO_LOG("next: %x\n", *p);
  76                 if (*p != 4)
  77                         continue;
  78                 i += 18;
  79                 p = buf + i;
  80                 PARA_INFO_LOG("next: %x\n", *p);
  81                 if (*p != 5)
  82                         continue;
  83                 i++;
  84                 p = buf + i;
  85                 decoder_length = aac_read_decoder_length(p, &description_len);
  86                 PARA_INFO_LOG("decoder length: %d\n", decoder_length);
  87                 i += description_len;
  88                 *skip = i;
  89                 return decoder_length;
  90         }
  91         return -E_ESDS;
  92 }
  93
  94 unsigned aac_read_int32(unsigned char *buf)
  95 {
  96         uint8_t *d = (uint8_t*)buf;
  97         return (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
  98 }
  99
 100
 101 int aac_find_entry_point(unsigned char *buf, unsigned buflen, int *skip)
 102 {
 103         int i, ret;
 104
 105         for (i = 0; i + 20 < buflen; i++) {
 106                 unsigned char *p = buf + i;
 107
 108                 if (p[0] != 's' || p[1] != 't' || p[2] != 'c' || p[3] != 'o')
 109                         continue;
 110                 PARA_INFO_LOG("found stco@%d\n", i);
 111                 i += 12;
 112                 ret = aac_read_int32(buf + i); /* first offset */
 113                 i += 4;
 114                 PARA_INFO_LOG("num entries: %d\n", ret);
 115                 *skip = i;
 116                 return ret;
 117         }
 118         PARA_WARNING_LOG("stco not found, buflen: %d\n", buflen);
 119         return -E_STCO;
 120 }
 121