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1.1 root 1: /*
1.1.1.5 root 2: Hatari - audio.c
3:
1.1.1.19 root 4: This file is distributed under the GNU General Public License, version 2
5: or at your option any later version. Read the file gpl.txt for details.
1.1.1.5 root 6:
7: This file contains the routines which pass the audio data to the SDL library.
1.1 root 8: */
1.1.1.13 root 9: const char Audio_fileid[] = "Hatari audio.c : " __DATE__ " " __TIME__;
1.1 root 10:
1.1.1.2 root 11: #include <SDL.h>
12:
1.1 root 13: #include "main.h"
14: #include "audio.h"
1.1.1.6 root 15: #include "configuration.h"
1.1.1.9 root 16: #include "log.h"
1.1 root 17: #include "sound.h"
1.1.1.15 root 18: #include "dmaSnd.h"
1.1.1.16 root 19: #include "falcon/crossbar.h"
1.1 root 20:
1.1.1.18 root 21: #include "screen.h"
22: #include "video.h" /* FIXME: video.h is dependent on HBL_PALETTE_LINES from screen.h */
23:
1.1 root 24:
1.1.1.15 root 25: int nAudioFrequency = 44100; /* Sound playback frequency */
26: bool bSoundWorking = false; /* Is sound OK */
1.1.1.20! root 27: static volatile bool bPlayingBuffer = false; /* Is playing buffer? */
1.1.1.15 root 28: int SoundBufferSize = 1024 / 4; /* Size of sound buffer (in samples) */
29: int CompleteSndBufIdx; /* Replay-index into MixBuffer */
30: int SdlAudioBufferSize = 0; /* in ms (0 = use default) */
1.1.1.18 root 31: int pulse_swallowing_count = 0; /* Sound disciplined emulation rate controlled by */
32: /* window comparator and pulse swallowing counter */
1.1 root 33:
1.1.1.2 root 34: /*-----------------------------------------------------------------------*/
1.1.1.11 root 35: /**
36: * SDL audio callback function - copy emulation sound to audio system.
37: */
1.1.1.7 root 38: static void Audio_CallBack(void *userdata, Uint8 *stream, int len)
1.1.1.2 root 39: {
1.1.1.12 root 40: Sint16 *pBuffer;
1.1.1.18 root 41: int i, window, nSamplesPerFrame;
1.1.1.7 root 42:
1.1.1.12 root 43: pBuffer = (Sint16 *)stream;
44: len = len / 4; // Use length in samples (16 bit stereo), not in bytes
1.1.1.9 root 45:
1.1.1.18 root 46: /* Adjust emulation rate within +/- 0.58% (10 cents) occasionally,
47: * to synchronize sound. Note that an octave (frequency doubling)
48: * has 12 semitones (12th root of two for a semitone), and that
49: * one semitone has 100 cents (1200th root of two for one cent).
50: * Ten cents are desired, thus, the 120th root of two minus one is
51: * multiplied by 1,000,000 to convert to microseconds, and divided
52: * by nScreenRefreshRate=60 to get a 96 microseconds swallow size.
53: * (2^(10cents/(12semitones*100cents)) - 1) * 10^6 / nScreenRefreshRate
54: * See: main.c - Main_WaitOnVbl()
55: */
56:
57: pulse_swallowing_count = 0; /* 0 = Unaltered emulation rate */
58:
59: if (ConfigureParams.Sound.bEnableSoundSync)
60: {
61: /* Sound synchronized emulation */
62: nSamplesPerFrame = nAudioFrequency/nScreenRefreshRate;
63: window = (nSamplesPerFrame > SoundBufferSize) ? nSamplesPerFrame : SoundBufferSize;
64:
65: /* Window Comparator for SoundBufferSize */
66: if (nGeneratedSamples < window + (window >> 1))
67: /* Increase emulation rate to maintain sound synchronization */
68: pulse_swallowing_count = -5793 / nScreenRefreshRate;
69: else
70: if (nGeneratedSamples > (window << 1) + (window >> 2))
71: /* Decrease emulation rate to maintain sound synchronization */
72: pulse_swallowing_count = 5793 / nScreenRefreshRate;
73:
74: /* Otherwise emulation rate is unaltered. */
75: }
76:
1.1.1.9 root 77: if (nGeneratedSamples >= len)
78: {
1.1.1.10 root 79: /* Enough samples available: Pass completed buffer to audio system
80: * by write samples into sound buffer and by converting them from
81: * 'signed' to 'unsigned' */
82: for (i = 0; i < len; i++)
83: {
1.1.1.12 root 84: *pBuffer++ = MixBuffer[(CompleteSndBufIdx + i) % MIXBUFFER_SIZE][0];
85: *pBuffer++ = MixBuffer[(CompleteSndBufIdx + i) % MIXBUFFER_SIZE][1];
1.1.1.10 root 86: }
1.1.1.9 root 87: CompleteSndBufIdx += len;
88: nGeneratedSamples -= len;
89: }
1.1.1.10 root 90: else /* Not enough samples available: */
1.1.1.9 root 91: {
1.1.1.10 root 92: for (i = 0; i < nGeneratedSamples; i++)
93: {
1.1.1.12 root 94: *pBuffer++ = MixBuffer[(CompleteSndBufIdx + i) % MIXBUFFER_SIZE][0];
95: *pBuffer++ = MixBuffer[(CompleteSndBufIdx + i) % MIXBUFFER_SIZE][1];
1.1.1.10 root 96: }
97: /* If the buffer is filled more than 50%, mirror sample buffer to fake the
98: * missing samples */
99: if (nGeneratedSamples >= len/2)
100: {
101: int remaining = len - nGeneratedSamples;
1.1.1.12 root 102: memcpy(pBuffer, stream+(nGeneratedSamples-remaining)*4, remaining*4);
1.1.1.10 root 103: }
1.1.1.9 root 104: CompleteSndBufIdx += nGeneratedSamples;
105: nGeneratedSamples = 0;
1.1.1.10 root 106:
1.1.1.9 root 107: }
1.1.1.10 root 108:
1.1.1.9 root 109: CompleteSndBufIdx = CompleteSndBufIdx % MIXBUFFER_SIZE;
1.1.1.2 root 110: }
111:
1.1 root 112:
1.1.1.2 root 113: /*-----------------------------------------------------------------------*/
1.1.1.11 root 114: /**
1.1.1.14 root 115: * Initialize the audio subsystem. Return true if all OK.
1.1.1.11 root 116: * We use direct access to the sound buffer, set to a unsigned 8-bit mono stream.
117: */
1.1.1.2 root 118: void Audio_Init(void)
1.1 root 119: {
1.1.1.9 root 120: SDL_AudioSpec desiredAudioSpec; /* We fill in the desired SDL audio options here */
1.1.1.5 root 121:
1.1.1.9 root 122: /* Is enabled? */
123: if (!ConfigureParams.Sound.bEnableSound)
124: {
125: /* Stop any sound access */
126: Log_Printf(LOG_DEBUG, "Sound: Disabled\n");
1.1.1.14 root 127: bSoundWorking = false;
1.1.1.9 root 128: return;
129: }
130:
131: /* Init the SDL's audio subsystem: */
132: if (SDL_WasInit(SDL_INIT_AUDIO) == 0)
133: {
134: if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0)
135: {
136: fprintf(stderr, "Could not init audio: %s\n", SDL_GetError() );
1.1.1.14 root 137: bSoundWorking = false;
1.1.1.9 root 138: return;
139: }
140: }
141:
142: /* Set up SDL audio: */
1.1.1.14 root 143: desiredAudioSpec.freq = nAudioFrequency;
1.1.1.15 root 144: desiredAudioSpec.format = AUDIO_S16SYS; /* 16-Bit signed */
145: desiredAudioSpec.channels = 2; /* stereo */
1.1.1.9 root 146: desiredAudioSpec.callback = Audio_CallBack;
147: desiredAudioSpec.userdata = NULL;
148:
1.1.1.15 root 149: /* In most case, setting samples to 1024 will give an equivalent */
150: /* sdl sound buffer of ~20-30 ms (depending on freq). */
151: /* But setting samples to 1024 for all the freq can cause some faulty */
152: /* OS sound drivers to add an important delay when playing sound at lower freq. */
153: /* In that case we use SdlAudioBufferSize (in ms) to compute a value */
154: /* of samples that matches the corresponding freq and buffer size. */
155: if ( SdlAudioBufferSize == 0 ) /* don't compute "samples", use default value */
156: desiredAudioSpec.samples = 1024; /* buffer size in samples */
157: else
158: {
159: int samples = (desiredAudioSpec.freq / 1000) * SdlAudioBufferSize;
160: int power2 = 1;
161: while ( power2 < samples ) /* compute the power of 2 just above samples */
162: power2 *= 2;
163:
164: //fprintf ( stderr , "samples %d power %d\n" , samples , power2 );
165: desiredAudioSpec.samples = power2; /* number of samples corresponding to the requested SdlAudioBufferSize */
166: }
167:
168:
169: if (SDL_OpenAudio(&desiredAudioSpec, NULL)) /* Open audio device */
1.1.1.9 root 170: {
171: fprintf(stderr, "Can't use audio: %s\n", SDL_GetError());
1.1.1.14 root 172: bSoundWorking = false;
173: ConfigureParams.Sound.bEnableSound = false;
1.1.1.9 root 174: SDL_QuitSubSystem(SDL_INIT_AUDIO);
175: return;
176: }
177:
1.1.1.15 root 178: SoundBufferSize = desiredAudioSpec.size; /* May be different than the requested one! */
179: SoundBufferSize /= 4; /* bytes -> samples (16 bit signed stereo -> 4 bytes per sample) */
1.1.1.9 root 180: if (SoundBufferSize > MIXBUFFER_SIZE/2)
181: {
182: fprintf(stderr, "Warning: Soundbuffer size is too big!\n");
183: }
184:
185: /* All OK */
1.1.1.14 root 186: bSoundWorking = true;
1.1.1.9 root 187: /* And begin */
1.1.1.14 root 188: Audio_EnableAudio(true);
1.1 root 189: }
190:
1.1.1.2 root 191:
192: /*-----------------------------------------------------------------------*/
1.1.1.11 root 193: /**
194: * Free audio subsystem
195: */
1.1.1.2 root 196: void Audio_UnInit(void)
1.1 root 197: {
1.1.1.9 root 198: if (bSoundWorking)
199: {
200: /* Stop */
1.1.1.14 root 201: Audio_EnableAudio(false);
1.1.1.2 root 202:
1.1.1.9 root 203: SDL_CloseAudio();
1.1.1.7 root 204:
1.1.1.14 root 205: bSoundWorking = false;
1.1.1.9 root 206: }
1.1 root 207: }
208:
1.1.1.2 root 209:
210: /*-----------------------------------------------------------------------*/
1.1.1.11 root 211: /**
212: * Lock the audio sub system so that the callback function will not be called.
213: */
1.1.1.5 root 214: void Audio_Lock(void)
1.1 root 215: {
1.1.1.9 root 216: SDL_LockAudio();
1.1 root 217: }
218:
1.1.1.2 root 219:
220: /*-----------------------------------------------------------------------*/
1.1.1.11 root 221: /**
222: * Unlock the audio sub system so that the callback function will be called again.
223: */
1.1.1.5 root 224: void Audio_Unlock(void)
1.1 root 225: {
1.1.1.9 root 226: SDL_UnlockAudio();
1.1 root 227: }
228:
1.1.1.2 root 229:
230: /*-----------------------------------------------------------------------*/
1.1.1.11 root 231: /**
232: * Set audio playback frequency variable, pass as PLAYBACK_xxxx
233: */
1.1.1.14 root 234: void Audio_SetOutputAudioFreq(int nNewFrequency)
1.1 root 235: {
1.1.1.9 root 236: /* Do not reset sound system if nothing has changed! */
1.1.1.14 root 237: if (nNewFrequency != nAudioFrequency)
1.1.1.9 root 238: {
1.1.1.14 root 239: /* Set new frequency */
240: nAudioFrequency = nNewFrequency;
1.1.1.9 root 241:
1.1.1.17 root 242: if (ConfigureParams.System.nMachineType == MACHINE_FALCON)
243: {
1.1.1.16 root 244: /* Compute Ratio between host computer sound frequency and Hatari's sound frequency. */
245: Crossbar_Compute_Ratio();
246: }
1.1.1.17 root 247: else if (ConfigureParams.System.nMachineType != MACHINE_ST)
248: {
1.1.1.16 root 249: /* Adapt LMC filters to this new frequency */
250: DmaSnd_Init_Bass_and_Treble_Tables();
251: }
252:
1.1.1.9 root 253: /* Re-open SDL audio interface if necessary: */
254: if (bSoundWorking)
255: {
256: Audio_UnInit();
257: Audio_Init();
258: }
259: }
1.1.1.17 root 260:
261: if ((ConfigureParams.System.nMachineType == MACHINE_ST) &&
1.1.1.20! root 262: (nAudioFrequency >= 40000))
1.1.1.17 root 263: {
264: /* Apply YM2149 C10 filter. */
265: UseLowPassFilter = true;
266: }
267: else
268: {
269: UseLowPassFilter = false;
270: }
1.1 root 271: }
272:
1.1.1.2 root 273:
274: /*-----------------------------------------------------------------------*/
1.1.1.11 root 275: /**
276: * Start/Stop sound buffer
277: */
1.1.1.12 root 278: void Audio_EnableAudio(bool bEnable)
1.1 root 279: {
1.1.1.9 root 280: if (bEnable && !bPlayingBuffer)
281: {
282: /* Start playing */
1.1.1.14 root 283: SDL_PauseAudio(false);
284: bPlayingBuffer = true;
1.1.1.9 root 285: }
286: else if (!bEnable && bPlayingBuffer)
287: {
288: /* Stop from playing */
1.1.1.14 root 289: SDL_PauseAudio(true);
290: bPlayingBuffer = false;
1.1.1.9 root 291: }
1.1 root 292: }
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