1 /* ScummVM - Graphic Adventure Engine
2 *
3 * ScummVM is the legal property of its developers, whose names
4 * are too numerous to list here. Please refer to the COPYRIGHT
5 * file distributed with this source distribution.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 */
22
23 #ifndef AUDIO_RATE_H
24 #define AUDIO_RATE_H
25
26 #include "common/scummsys.h"
27
28 namespace Audio {
29
30 class AudioStream;
31
32 typedef int16 st_sample_t;
33 typedef uint16 st_volume_t;
34 typedef uint32 st_size_t;
35 typedef uint32 st_rate_t;
36
37 /* Minimum and maximum values a sample can hold. */
38 enum {
39 ST_SAMPLE_MAX = 0x7fffL,
40 ST_SAMPLE_MIN = (-ST_SAMPLE_MAX - 1L)
41 };
42
43 enum {
44 ST_EOF = -1,
45 ST_SUCCESS = 0
46 };
47
clampedAdd(int16 & a,int b)48 static inline void clampedAdd(int16& a, int b) {
49 register int val;
50 #ifdef OUTPUT_UNSIGNED_AUDIO
51 val = (a ^ 0x8000) + b;
52 #else
53 val = a + b;
54 #endif
55
56 if (val > ST_SAMPLE_MAX)
57 val = ST_SAMPLE_MAX;
58 else if (val < ST_SAMPLE_MIN)
59 val = ST_SAMPLE_MIN;
60
61 #ifdef OUTPUT_UNSIGNED_AUDIO
62 a = ((int16)val) ^ 0x8000;
63 #else
64 a = val;
65 #endif
66 }
67
68 class RateConverter {
69 public:
RateConverter()70 RateConverter() {}
~RateConverter()71 virtual ~RateConverter() {}
72
73 /**
74 * @return Number of sample pairs written into the buffer.
75 */
76 virtual int flow(AudioStream &input, st_sample_t *obuf, st_size_t osamp, st_volume_t vol_l, st_volume_t vol_r) = 0;
77
78 virtual int drain(st_sample_t *obuf, st_size_t osamp, st_volume_t vol) = 0;
79 };
80
81 RateConverter *makeRateConverter(st_rate_t inrate, st_rate_t outrate, bool stereo, bool reverseStereo = false);
82
83 } // End of namespace Audio
84
85 #endif
86