AudioSampleValue.h

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00001 /*
00002  * steghide 0.5.1 - a steganography program
00003  * Copyright (C) 1999-2003 Stefan Hetzl <shetzl@chello.at>
00004  *
00005  * This program is free software; you can redistribute it and/or
00006  * modify it under the terms of the GNU General Public License
00007  * as published by the Free Software Foundation; either version 2
00008  * of the License, or (at your option) any later version.
00009  *
00010  * This program is distributed in the hope that it will be useful,
00011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013  * GNU General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU General Public License
00016  * along with this program; if not, write to the Free Software
00017  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
00018  *
00019  */
00020 
00021 #ifndef SH_AUDIOSAMPLEVALUE_H
00022 #define SH_AUDIOSAMPLEVALUE_H
00023 
00024 #include "CvrStgFile.h"
00025 #include "SampleValue.h"
00026 #include "common.h"
00027 
00033 enum AUDIOSAMPLETYPE {
00035         AuMuLaw,
00037         AuPCM8,
00039         AuPCM16,
00041         AuPCM32
00042 } ;
00043 
00048 template<AUDIOSAMPLETYPE Type, class ValueType>
00049 class AudioSampleValue : public SampleValue {
00050         public:
00051         AudioSampleValue (ValueType v) ;
00052 
00053         ValueType getValue (void) const { return Value ; } ;
00054 
00055         SampleValue* getNearestTargetSampleValue (EmbValue t) const ;
00056         UWORD32 calcDistance (const SampleValue* s) const ;
00057         std::string getName (void) const ;
00058 
00059         private:
00060         ValueType Value ;
00061         static const ValueType MinValue ;
00062         static const ValueType MaxValue ;
00063 
00064         UWORD32 calcKey (ValueType v) const { return (v - MinValue) ; } ;
00065         EmbValue calcEValue (ValueType v) const { return ((EmbValue) ((v - MinValue) % Globs.TheCvrStgFile->getEmbValueModulus())) ; } ;
00066 } ;
00067 
00068 template<AUDIOSAMPLETYPE Type, class ValueType>
00069 AudioSampleValue<Type,ValueType>::AudioSampleValue (ValueType v)
00070         : SampleValue(), Value(v)
00071 {
00072         Key = calcKey(v) ;
00073         EValue = calcEValue(v) ;
00074 }
00075 
00076 template<AUDIOSAMPLETYPE Type, class ValueType>
00077 UWORD32 AudioSampleValue<Type,ValueType>::calcDistance (const SampleValue* s) const
00078 {
00079         const AudioSampleValue<Type,ValueType>* sample = (const AudioSampleValue<Type,ValueType>*) s ;
00080         /* If s is not a correct AudioSampleValue then we get into real trouble here.
00081         But calcDistance is called very often, a dynamic_cast costs a lot of time and
00082         it does not make sense to pass anything but a correct AudioSampleValue as s anyway. */
00083 
00084         if (sample->Value > Value) {
00085                 return sample->Value - Value ;
00086         }
00087         else {
00088                 return Value - sample->Value ;
00089         }
00090 }
00091 
00092 template<AUDIOSAMPLETYPE Type, class ValueType>
00093 SampleValue* AudioSampleValue<Type,ValueType>::getNearestTargetSampleValue (EmbValue t) const
00094 {
00095         ValueType val_up = Value, val_down = Value, newval = 0 ;
00096         bool found = false ;
00097 
00098         do {
00099                 if (val_up < MaxValue) {
00100                         val_up++ ;
00101                 }
00102                 if (val_down > MinValue) {
00103                         val_down-- ;
00104                 }
00105 
00106                 if (calcEValue(val_up) == t && calcEValue(val_down) == t) {
00107                         if (RndSrc.getBool()) {
00108                                 newval = val_up ;
00109                         }
00110                         else {
00111                                 newval = val_down ;
00112                         }
00113                         found = true ;
00114                 }
00115                 else if (calcEValue(val_up) == t) {
00116                         newval = val_up ;
00117                         found = true ;
00118                 }
00119                 else if (calcEValue(val_down) == t) {
00120                         newval = val_down ;
00121                         found = true ;
00122                 }
00123         } while (!found) ;
00124 
00125         return ((SampleValue *) new AudioSampleValue<Type,ValueType> (newval)) ;
00126 }
00127 
00128 template<AUDIOSAMPLETYPE Type, class ValueType>
00129 std::string AudioSampleValue<Type,ValueType>::getName (void) const
00130 {
00131         char buf[128] ;
00132         sprintf (buf, "%ld", (long) Value) ;
00133         return std::string (buf) ;
00134 }
00135 
00136 #endif // ndef SH_AUDIOSAMPLEVALUE_H

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