1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/* ScummVM - Scumm Interpreter
* Copyright (C) 2005 The ScummVM project
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Header$
*
*/
#include "common/stdafx.h"
#include "common/stream.h"
#include "sound/audiostream.h"
#include "sound/adpcm.h"
// Routines to convert 12 bit linear samples to the
// Dialogic or Oki ADPCM coding format aka VOX.
// See also <http://www.comptek.ru/telephony/tnotes/tt1-13.html>
//
// In addition, also IMA ADPCM is supported.
template <typesADPCM TYPE>
class ADPCMInputStream : public AudioStream {
private:
bool _evenPos;
byte _lastByte;
Common::SeekableReadStream *_stream;
uint32 _endpos;
struct adpcmStatus {
int16 last;
int16 stepIndex;
} _status;
int16 stepAdjust(byte);
int16 decode(byte);
public:
ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size);
~ADPCMInputStream() {};
int readBuffer(int16 *buffer, const int numSamples);
bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
bool isStereo() const { return false; }
int getRate() const { return 22050; }
};
template <typesADPCM TYPE>
ADPCMInputStream<TYPE>::ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size)
: _stream(stream), _evenPos(true) {
_status.last = 0;
_status.stepIndex = 0;
_endpos = stream->pos() + size;
}
template <typesADPCM TYPE>
int ADPCMInputStream<TYPE>::readBuffer(int16 *buffer, const int numSamples) {
int samples;
// Since we process high and low nibbles separately never check buffer end
// on low nibble
for (samples = 0; !_evenPos || samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples++) {
if (_evenPos) {
_lastByte = _stream->readByte();
buffer[samples] = decode((_lastByte >> 4) & 0x0f);
} else {
buffer[samples] = decode(_lastByte & 0x0f);
}
_evenPos = !_evenPos;
}
return samples;
}
// adjust the step for use on the next sample.
template <typesADPCM TYPE>
int16 ADPCMInputStream<TYPE>::stepAdjust(byte code) {
static const int16 adjusts[] = {-1, -1, -1, -1, 2, 4, 6, 8};
return adjusts[code & 0x07];
}
static const int16 okiStepSize[49] = {
16, 17, 19, 21, 23, 25, 28, 31,
34, 37, 41, 45, 50, 55, 60, 66,
73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658,
724, 796, 876, 963, 1060, 1166, 1282, 1411,
1552
};
// Decode Linear to ADPCM
template <>
int16 ADPCMInputStream<kADPCMOki>::decode(byte code) {
int16 diff, E, SS, samp;
SS = okiStepSize[_status.stepIndex];
E = SS/8;
if (code & 0x01)
E += SS/4;
if (code & 0x02)
E += SS/2;
if (code & 0x04)
E += SS;
diff = (code & 0x08) ? -E : E;
samp = _status.last + diff;
// Clip the values to +/- 2^11 (supposed to be 12 bits)
if (samp > 2048)
samp = 2048;
if (samp < -2048)
samp = -2048;
_status.last = samp;
_status.stepIndex += stepAdjust(code);
if (_status.stepIndex < 0)
_status.stepIndex = 0;
if (_status.stepIndex > 48)
_status.stepIndex = 48;
// * 16 effectively converts 12-bit input to 16-bit output
return samp * 16;
}
static const uint16 imaStepTable[89] = {
7, 8, 9, 10, 11, 12, 13, 14,
16, 17, 19, 21, 23, 25, 28, 31,
34, 37, 41, 45, 50, 55, 60, 66,
73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658,
724, 796, 876, 963, 1060, 1166, 1282, 1411,
1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
7132, 7845, 8630, 9493,10442,11487,12635,13899,
15289,16818,18500,20350,22385,24623,27086,29794,
32767
};
template <>
int16 ADPCMInputStream<kADPCMIma>::decode(byte code) {
int32 diff, E, SS, samp;
SS = imaStepTable[_status.stepIndex];
E = SS/8;
if (code & 0x01)
E += SS/4;
if (code & 0x02)
E += SS/2;
if (code & 0x04)
E += SS;
diff = (code & 0x08) ? -E : E;
samp = _status.last + diff;
if (samp < -32768)
samp = -32768;
else if (samp > 32767)
samp = 32767;
_status.last = samp;
_status.stepIndex += stepAdjust(code);
if (_status.stepIndex < 0)
_status.stepIndex = 0;
if (_status.stepIndex > 88)
_status.stepIndex = 88;
return samp;
}
AudioStream *makeADPCMStream(Common::SeekableReadStream &stream, uint32 size, typesADPCM type) {
AudioStream *audioStream;
switch (type) {
case kADPCMOki:
audioStream = new ADPCMInputStream<kADPCMOki>(&stream, size);
break;
case kADPCMIma:
audioStream = new ADPCMInputStream<kADPCMIma>(&stream, size);
break;
default:
error("Unsupported ADPCM encoding");
break;
}
return audioStream;
}
|