aac_common.c

   1 /*
   2  * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6 /*
   7  * based in parts on libfaad, Copyright (C) 2003-2005 M. Bakker,
   8  * Ahead Software AG
   9  */
  10
  11 /** \file aac_common.c common functions of aac_afh and aadcec */
  12
  13 #include "para.h"
  14 #include "aac.h"
  15 #include "error.h"
  16
  17 /**
  18  * get a new libfaad decoder handle
  19  *
  20  */
  21 NeAACDecHandle aac_open(void)
  22 {
  23         NeAACDecHandle h = NeAACDecOpen();
  24         NeAACDecConfigurationPtr c = NeAACDecGetCurrentConfiguration(h);
  25
  26         c->defObjectType = LC;
  27         c->outputFormat = FAAD_FMT_16BIT;
  28         c->downMatrix = 0;
  29         NeAACDecSetConfiguration(h, c);
  30         return h;
  31 };
  32
  33 static unsigned long aac_read_decoder_length(unsigned char *buf, int *description_len)
  34 {
  35         uint8_t b;
  36         uint8_t numBytes = 0;
  37         unsigned long length = 0;
  38
  39         do {
  40                 b = buf[numBytes];
  41                 numBytes++;
  42                 length = (length << 7) | (b & 0x7F);
  43         } while
  44                 ((b & 0x80) && numBytes < 4);
  45         *description_len = numBytes;
  46         return length;
  47 }
  48
  49 /**
  50  * search for the position and the length of the decoder configuration
  51  *
  52  * \param buf buffer to seach
  53  * \param buflen length of \a buf
  54  * \param skip Upon succesful return, this contains the offset in \a buf where
  55  * the decoder config starts.
  56  * \param decoder_length result pointer that is filled in with the length of
  57  * the decoder configuration on success.
  58  *
  59  * \return positive on success, negative on errors
  60  */
  61 int aac_find_esds(unsigned char *buf, size_t buflen, size_t *skip,
  62                 unsigned long *decoder_length)
  63 {
  64         size_t i;
  65
  66         for (i = 0; i + 4 < buflen; i++) {
  67                 unsigned char *p = buf + i;
  68                 int description_len;
  69
  70                 if (p[0] != 'e' || p[1] != 's' || p[2] != 'd' || p[3] != 's')
  71                         continue;
  72                 i += 8;
  73                 p = buf + i;
  74                 PARA_INFO_LOG("found esds@%zu, next: %x\n", i, *p);
  75                 if (*p == 3)
  76                         i += 8;
  77                 else
  78                         i += 6;
  79                 p = buf + i;
  80                 PARA_INFO_LOG("next: %x\n", *p);
  81                 if (*p != 4)
  82                         continue;
  83                 i += 18;
  84                 p = buf + i;
  85                 PARA_INFO_LOG("next: %x\n", *p);
  86                 if (*p != 5)
  87                         continue;
  88                 i++;
  89                 p = buf + i;
  90                 *decoder_length = aac_read_decoder_length(p, &description_len);
  91                 PARA_INFO_LOG("decoder length: %lu\n", *decoder_length);
  92                 i += description_len;
  93                 *skip = i;
  94                 return 1;
  95         }
  96         return -E_ESDS;
  97 }
  98
  99 /**
 100  * search for the first entry in the stco table
 101  *
 102  * \param buf buffer to seach
 103  * \param buflen length of \a buf
 104  * \param skip Upon succesful return, this contains the number
 105  * of bytes to skip from the input buffer.
 106  *
 107  * \return the position of the first entry in the table on success,
 108  * -E_STCO on errors.
 109  */
 110 ssize_t aac_find_entry_point(unsigned char *buf, size_t buflen, size_t *skip)
 111 {
 112         ssize_t ret;
 113         size_t i;
 114
 115         for (i = 0; i + 20 < buflen; i++) {
 116                 unsigned char *p = buf + i;
 117
 118                 if (p[0] != 's' || p[1] != 't' || p[2] != 'c' || p[3] != 'o')
 119                         continue;
 120                 PARA_INFO_LOG("found stco@%zu\n", i);
 121                 i += 12;
 122                 ret = aac_read_int32(buf + i); /* first offset */
 123                 i += 4;
 124                 PARA_INFO_LOG("entry point: %zd\n", ret);
 125                 *skip = i;
 126                 return ret;
 127         }
 128         PARA_WARNING_LOG("stco not found, buflen: %zu\n", buflen);
 129         return -E_STCO;
 130 }