interpretor/libsndfile-1.0.25/src/audio_detect.c

   1 /*
   2 ** Copyright (C) 1999-2011 Erik de Castro Lopo <erikd@mega-nerd.com>
   3 **
   4 ** This program is free software; you can redistribute it and/or modify
   5 ** it under the terms of the GNU Lesser General Public License as published by
   6 ** the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU Lesser 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 02111-1307, USA.
  17 */
  18
  19
  20 #include "sfconfig.h"
  21
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24
  25 #if HAVE_UNISTD_H
  26 #include <unistd.h>
  27 #endif
  28
  29 #include <string.h>
  30 #include <errno.h>
  31
  32 #include "common.h"
  33
  34 typedef struct
  35 {       int le_float ;
  36         int be_float ;
  37         int le_int_24_32 ;
  38         int be_int_24_32 ;
  39 } VOTE ;
  40
  41
  42 static void vote_for_format (VOTE * vote, const unsigned char * data, int datalen) ;
  43
  44 int
  45 audio_detect (SF_PRIVATE * psf, AUDIO_DETECT *ad, const unsigned char * data, int datalen)
  46 {       VOTE vote ;
  47
  48         if (psf == NULL)
  49                 return 0 ;
  50
  51         if (ad == NULL || datalen < 256)
  52                 return 0 ;
  53
  54         vote_for_format (&vote, data, datalen) ;
  55
  56         psf_log_printf (psf, "audio_detect :\n"
  57                         "    le_float     : %d\n"
  58                         "    be_float     : %d\n"
  59                         "    le_int_24_32 : %d\n"
  60                         "    be_int_24_32 : %d\n",
  61                         vote.le_float, vote.be_float, vote.le_int_24_32, vote.be_int_24_32) ;
  62
  63         if (0) puts (psf->logbuffer) ;
  64
  65         if (ad->endianness == SF_ENDIAN_LITTLE && vote.le_float > (3 * datalen) / 4)
  66         {       /* Almost certainly 32 bit floats. */
  67                 return SF_FORMAT_FLOAT ;
  68                 } ;
  69
  70         if (ad->endianness == SF_ENDIAN_LITTLE && vote.le_int_24_32 > (3 * datalen) / 4)
  71         {       /* Almost certainly 24 bit data stored in 32 bit ints. */
  72                 return SF_FORMAT_PCM_32 ;
  73                 } ;
  74
  75         return 0 ;
  76 } /* data_detect */
  77
  78 static void
  79 vote_for_format (VOTE * vote, const unsigned char * data, int datalen)
  80 {
  81         int k ;
  82
  83         memset (vote, 0, sizeof (VOTE)) ;
  84
  85         datalen -= datalen % 4 ;
  86
  87         for (k = 0 ; k < datalen ; k ++)
  88         {       if ((k % 4) == 0)
  89                 {       if (data [k] == 0 && data [k + 1] != 0)
  90                                 vote->le_int_24_32 += 4 ;
  91
  92                         if (data [2] != 0 && data [3] == 0)
  93                                 vote->le_int_24_32 += 4 ;
  94
  95                         if (data [0] != 0 && data [3] > 0x43 && data [3] < 0x4B)
  96                                 vote->le_float += 4 ;
  97
  98                         if (data [3] != 0 && data [0] > 0x43 && data [0] < 0x4B)
  99                                 vote->be_float += 4 ;
 100                         } ;
 101                 } ;
 102
 103         return ;
 104 } /* vote_for_format */
 105