1 /*
2 * sdl-sound without SDL_mixer.dll
3 *
4 * This file is part of the Simutrans project under the artistic license.
5 */
6
7
8 #include <SDL2/SDL.h>
9 #include <string.h>
10 #include "sound.h"
11 #include "../simmem.h"
12 #include "../simdebug.h"
13 #include <stdio.h>
14
15 /*
16 * Hajo: flag if sound module should be used
17 */
18 static int use_sound = 0;
19
20 /*
21 * defines the number of channels available
22 */
23 #define CHANNELS 4
24
25
26 /*
27 * this structure contains the data for one sample
28 */
29 struct sample {
30 /* the buffer containing the data for the sample, the format
31 * must always be identical to the one of the system output
32 * format */
33 Uint8 *audio_data;
34
35 Uint32 audio_len; /* number of samples in the audio data */
36 };
37
38
39 /* this list contains all the samples
40 */
41 static sample samples[64];
42
43 /* all samples are stored chronologically there
44 */
45 static int samplenumber = 0;
46
47
48 /* this structure contains the information about one channel
49 */
50 struct channel {
51 Uint32 sample_pos; /* the current position inside this sample */
52 Uint8 sample; /* which sample is played, 255 for no sample */
53 Uint8 volume; /* the volume this channel should be played */
54 };
55
56
57 /* this array contains all the information of the currently played samples */
58 static channel channels[CHANNELS];
59
60
61 /* the format of the output audio channel in use
62 * all loaded waved need to be converted to this format
63 */
64 static SDL_AudioSpec output_audio_format;
65
66 static SDL_AudioDeviceID audio_device;
67
68
sdl_sound_callback(void *,Uint8 * stream,int len)69 void sdl_sound_callback(void *, Uint8 * stream, int len)
70 {
71 memset(stream, 0, len); // SDL2 requires the output stream to be fully written on every callback.
72
73 /*
74 * add all the sample that need to be played
75 */
76 for( int c = 0; c < CHANNELS; c++ ) {
77 /*
78 * only do something, if the channel is used
79 */
80 if (channels[c].sample != 255) {
81 sample * smp = &samples[channels[c].sample];
82
83 /*
84 * add sample
85 */
86 if (len + channels[c].sample_pos >= smp->audio_len ) {
87 // SDL_MixAudio(stream, smp->audio_data + channels[c].sample_pos, smp->audio_len - channels[c].sample_pos, channels[c].volume);
88 channels[c].sample = 255;
89 }
90 else {
91 SDL_MixAudioFormat(stream, smp->audio_data + channels[c].sample_pos, output_audio_format.format, len, channels[c].volume);
92 channels[c].sample_pos += len;
93 }
94 }
95 }
96 }
97
98
99 /**
100 * Sound initialisation routine
101 */
dr_init_sound()102 bool dr_init_sound()
103 {
104 int sound_ok = 0;
105 if(use_sound!=0) {
106 return use_sound; // avoid init twice
107 }
108 use_sound = 1;
109
110 // initialize SDL sound subsystem
111 if (SDL_InitSubSystem(SDL_INIT_AUDIO) != -1) {
112
113 // open an audio channel
114 SDL_AudioSpec desired;
115
116 desired.freq = 22050;
117 desired.channels = 1;
118 desired.format = AUDIO_S16SYS;
119 desired.samples = 1024;
120 desired.userdata = NULL;
121
122 desired.callback = sdl_sound_callback;
123
124 if( (audio_device = SDL_OpenAudioDevice( NULL, 0, &desired, &output_audio_format, SDL_AUDIO_ALLOW_ANY_CHANGE )) ) {
125 // allow any change as loaded .wav files are converted to output format upon loading
126
127 int i;
128
129 // finished initializing
130 sound_ok = 1;
131
132 for (i = 0; i < CHANNELS; i++)
133 channels[i].sample = 255;
134
135 // start playing sounds
136 SDL_PauseAudioDevice(audio_device, 0);
137
138 }
139 else {
140 dbg->error("dr_init_sound()", "Could not open required audio channel. Muting");
141 SDL_QuitSubSystem(SDL_INIT_AUDIO);
142 }
143 }
144 else {
145 dbg->error("dr_init_sound()", "Could not initialize sound system. Muting");
146 }
147
148 use_sound = sound_ok ? 1: -1;
149 return sound_ok;
150 }
151
152
153 /**
154 * loads a sample
155 * @return a handle for that sample or -1 on failure
156 * @author Hj. Malthaner
157 */
dr_load_sample(const char * filename)158 int dr_load_sample(const char *filename)
159 {
160 if(use_sound>0 && samplenumber<64) {
161
162 SDL_AudioSpec wav_spec;
163 SDL_AudioCVT wav_cvt;
164 Uint8 *wav_data;
165 Uint32 wav_length;
166 sample smp;
167
168 /* load the sample */
169 if (SDL_LoadWAV(filename, &wav_spec, &wav_data, &wav_length) == NULL) {
170 dbg->warning("dr_load_sample", "could not load wav (%s)", SDL_GetError());
171 return -1;
172 }
173
174 /* convert the loaded wav to the internally used sound format */
175 if (SDL_BuildAudioCVT(&wav_cvt,
176 wav_spec.format, wav_spec.channels, wav_spec.freq,
177 output_audio_format.format,
178 output_audio_format.channels,
179 output_audio_format.freq) < 0) {
180 dbg->warning("dr_load_sample", "could not create conversion structure");
181 SDL_FreeWAV(wav_data);
182 return -1;
183 }
184
185 wav_cvt.buf = MALLOCN(Uint8, wav_length * wav_cvt.len_mult);
186 wav_cvt.len = wav_length;
187 memcpy(wav_cvt.buf, wav_data, wav_length);
188
189 SDL_FreeWAV(wav_data);
190
191 if (SDL_ConvertAudio(&wav_cvt) < 0) {
192 dbg->warning("dr_load_sample", "could not convert wav to output format");
193 return -1;
194 }
195
196 /* save the data */
197 smp.audio_data = wav_cvt.buf;
198 smp.audio_len = wav_cvt.len_cvt;
199 samples[samplenumber] = smp;
200 dbg->message("dr_load_sample", "Loaded %s to sample %i.",filename,samplenumber);
201
202 return samplenumber++;
203 }
204 return -1;
205 }
206
207
208 /**
209 * plays a sample
210 * @param key the key for the sample to be played
211 * @author Hj. Malthaner
212 */
dr_play_sample(int sample_number,int volume)213 void dr_play_sample(int sample_number, int volume)
214 {
215 if(use_sound>0) {
216
217 int c;
218
219 if (sample_number == -1) {
220 return;
221 }
222
223 /* find an empty channel, and play */
224 for (c = 0; c < CHANNELS; c++) {
225 if (channels[c].sample == 255) {
226 channels[c].sample = sample_number;
227 channels[c].sample_pos = 0;
228 channels[c].volume = volume * SDL_MIX_MAXVOLUME >> 8;
229 break;
230 }
231 }
232 }
233 }
234